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Palynology of tertiary sediments from tropical areas
Review of Palaeobotany and Palynology Elsevier Publishing Company, Amsterdam - Printed in The Netherlands
P A L Y N O L O G Y OF TERTIARY SEDIMENTS FROM TROPICAL AREAS J. H. G E R M E R A A D , C. A. HOPPING ANI~ J. MULLER ~
Bataafse Internationale Petroleum Maatschappij, The Hag,e (The Netherlands) (Received February 8, 1968)
SUMMARY
This article deals with the most important aspects of nearly twenty years of intensive study of the pollen-and-spore content of Tertiary sediments in some parts of tropical South America, Africa and Asia. For a proper evaluation, the character of the data, including the selection and preparation of the samples, the diversity of previous recording and the statistically achieved uniformity in presentation of these basic data needs a full exposition, given in the introduction. This is directly followed by an explanation of the process of elimination of all stratigraphically unimportant species. The resulting interpretation of climatic and topographical influences on the dispersal of pollen and spores is illustrated with examples from the fossil record. The disturbing effect of redeposition forms a problem, which in some cases can be solved. Now that the main ways of dispersal of pollen and spores are understood, the characteristics of the three major depositional environments can be distinguished by purely statistical analysis, without necessarily having any botanical information from probably related Recent plant species. Additionally botany and palaeontology may bring supporting evidence. This many-sided approach leads to the discrimination between local and regional features of environmental or timestratigraphical significance which is needed for the evaluation of long-distance correlation. As a result the marker species can be classified into: (1) a restricted number of pantropical marker species; (2) a larger number of marker species which occurred in both the South American and west African regions, tropical today (transatlantic distribution); and (3) a still greater quantity of species which are of significance only within a single botanical province (intracontinental distribution). Thus a broad stratigraphical framework on a pantropical scale is established, which may be further subdivided regionally. These three systems of subzonation are compared with independent zoopalaeontological time-stratigraphical correlation and discussed in great detail, with special emphasis on the Carribean data. 1 Present address: Rijksherbarium, State University, Leiden (The Netherlands).
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
189
The major palynological changes marking the boundaries of the pantropical subzonation are thought to reflect the evolution of new groups of plants. They are mostly marked by a gradual incoming of pollen types. Extinction of plants is stratigraphically of less value, since they may have survived longer in one area than in another. Climatic boundaries are next in importance, but in general they are more restricted to specific regions. Similarly the immigration of plants, although producing sharp and useful boundaries, is only of regional value. Of least significance for regional correlation are the locally restricted boundaries which are caused by changes in habitat or dispersal. They may still be valuable for studies within one basin. An intriguing aspect of the palynological studies is formed by the possible affinity of the fossil type with Recent botanical species. Such affinities are obviously present in many fossil types. Whereas most are restricted to the level of family relationship, some interesting cases of much closer affinity are recorded here. In exceptional cases the morphogenetic development and migration of a restricted group of related pollen types can be traced. In the final section of this paper the species selected for this study have been formally described and illustrated; they include several new ones. The study is further documented by distribution charts and sections showing the stratigraphical significance of the marker types, as discussed in detail in the stratigraphical section.
INTRODUCTION
This paper presents some of the results obtained in twenty years of palynological investigation of Tertiary sediments from tropical areas by companies of the Royal Dutch/Shell Group. The primary purpose of this investigation was to arrive at a better interpretation of the stratigraphy of those Tertiary sedimentary basins where other means of correlation failed. Of course it is not possible in this paper to do more than present an outline of the large amount of work done and to select for discussion a few topics which appear to be of more general interest. Documentation will also be restricted to selected examples.
MATERIALS AND METHODS
The restriction of the subject of this paper to the Tertiary of tropical areas is due to a combination of factors. Firstly, the tropics represent a natural geobotanical unit. Secondly, palynological research by Shell was initially mainly concerned with the Tertiary sediments of northern South America, Nigeria and Borneo. Thirdly, the amount of detailed information on the Upper Cretaceous palynolo190
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
gical succession in these areas is still very scanty and the base of the Tertiary represents, therefore, at the present state of knowledge, a logical lower limit. Pleistocene strata have been studied too, but Holocene sediments have been left out of consideration because of lack of information. Geographically the main emphasis will be put on the South American data, which are by far the most extensive, covering Colombia, Venezuela, Trinidad and the Guianas. From Africa only the Nigerian Tertiary succession is adequately known. In the Far East, Borneo has supplied valuable information, but here the stratigraphical coverage is incomplete, data on the Eocene being very limited. The number of samples on which the study is based, is very large. Only samples collected at the surface and cores and sidewall samples taken in wells have been studied. As far as possible sections were chosen which contained, or were situated in close proximity to, samples dated by other means. Tropical Tertiary pollen floras are very rich in species and the average type collection may easily contain 800-1,000 different species. For stratigraphical purposes generally less than 200 are of importance per area. For a comprehensive review, such as this, a further reduction is desirable and only 49 species are discussed. These are, firstly, the species used to establish the major zonation, and some which are of importance for elucidating local correlation problems. In addition a few species of intrinsic botanical interest are discussed. Fossil species have as far as possible been referred to published ones 1. The introduction of new names has thus been kept to a minimum. Preparation of samples was mainly by standard techniques, modified according to local needs. For Neogene material treatment with HF, followed by bromoform separation, is generally sufficient, although when much plant debris is still present acetolysis may be helpful. For Palaeogene sediments slight oxidation with Schulze's mixture may be advantageous. The majority of the sediments examined consisted of clay and shale, silt or siltstone with varying amounts of carbonaceous material. Sandy sediments or coals were generally avoided. The basic data are presented on distribution charts accompanied by all pertinent lithostratigraphical and additional palaeontological information (Fig.l14). Again it must be emphasized that only examples are given. A complete documentation would have been impossible because of lack of space. However, the range chart (Fig.15) presents a compilation of all the data assembled for this study. Unfortunately, when palynological work was started in the different areas, no uniform system of recording data was adopted. Sometimes percentages were 1 In this connection we should like to express our gratitude for the facilities extended to us by Dr. T. van der H a m m e n (Amsterdam) and his staff, which enabled us to study the type collections not only of already described species but also of types to be described in future publications.
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
191
calculated on the basis of a pollen sum; in other cases a rough estimate of the abundance of the species was given. In order to create uniformity in the presentation of these quantitative data on our distribution charts, the occurrences are expressed as a value for the probability of re-observation, i.e., if a specified number of additional specimens from a new sample of the same rock or stratum were to be investigated. This re-observation of the species may be in any number of specimens (grains), including one only. This chance of re-observation is computed according to the following formula: a
P=I--(1--
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where a : the amount, that is the number of grains of the single species observed in the old sample; N : the sum of the amounts of all species, that is the total number of grains or pollen sum observed in the old sample; M : the sum of the amounts of all species in the new sample. Depending on the accuracy required by the palynological investigation and the time and sample material available, the value of M may be taken larger or smaller than 100. For technical reasons related to the type of computer at present in use for palynological data processing, the value of M is here taken to be 88. This conforms approximately to the current sample size of 70-I00 specimens of the selected species. The advantage of such a relatively small sample size lies mainly in the possibility of examining large numbers of samples within a short time, which is essential for routine work, both stratigraphically and statistically, and is far more informative than a few samples with large pollen sums. In general the counting of the marker species takes place in two phases. First, an analysis is made of the whole flora in which the dominant species like Rhizophora are also counted. The second part of the microscopical investigation is concerned only with the more rare but important markers, among which, e.g. Asteraceae (Compositae). To save time dominant species are no longer counted, but statistically it is not permissible to multiply the amount counted to get the corresponding figure. Therefore, the probability of re-observation of, for instance, Rhizophora pollen is calculated from the first pollen sum, but the probability of re-observation of the rare markers like Echitricolporites spinosus from the second pollen sum. Example." I - - c o u n t o f t h e w h o l e f l o r a , i n c l u d i n g , i n t e r alia, Rhizophora -- 100 g r a i n s . c o u n t o f t h e s p e c i a l s e l e c t i o n , e x c l u d i n g Rhizophora : 84 g r a i n s . A m o u n t o f Rhizophora in ' T ' : 8 0 g r a i n s , p r o b a b i l i t y o f r e - o b s e r v a t i o n = ! - - (1 - 8 0 / 1 0 0 ) ss : 1.00. A m o u n t o f Echitricolporites sphwsus in " I " = l g r a i n , p r o b a b i l i t y o f r e - o b s e r v a t i o n = 1 - - (I - - 1/100) ss == 0 . 5 9 0 . A m o u n t o f Echitricolporites spinosus in " l I " = 4 g r a i n s , p r o b a b i l i t y o f r e - o b s e r v a t i o n = 1 - - ( I - - 4 / 8 4 ) ss = 0 . 9 8 6 . II :
192
Rev. Palaeobotan. Palynol.,
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Since Echitricolporites spinosus is part of the special marker selection, the probability
of re-observation of this species in I is of little interest and is not recorded on the distribution charts presented. This example also shows the importance of further counting of the selected species. In order to avoid the impression of high accuracy and to facilitate visual evaluation of the charts, the probability values on the distribution charts (Fig.l-14) were grouped into classes and each class was indicated in the following way: P 0.01-0.75 -- . P 0.75-0.90 = / P 0.90-0.95 = o P 0.95-0.99 = P 0.99-1.00 = • An interrupted vertical line on some distribution charts indicates a distribution of a species which was not counted but which appeared common to abundant in most samples of the interval examined.
INTERPRETATION OF' DATA
The practical purpose of our investigations can be briefly stated as the establishment of a time-stratigraphical zonation, adapted to the scale of the geological problem under investigation. To achieve this goal a discrimination between stratigraphically reliable and unreliable pollen and spore types is necessary. The problems may vary from detailed correlation between wells a few kilometres apart in order to solve, for instance, tectonical complications, to broad correlation between sediments of widely differing facies hundreds or thousands of kilometres apart in different basins of deposition. It is of special importance to evaluate, for every part of the zonation, the scale on which it is valid, together with an estimate of the degree of accuracy. The selection of the 49 species discussed and the zonation established in this paper were preceded by a detailed study of the factors which influenced the regional significance of these markers. It is of course impossible to present a full account of this elimination process. Instead an attempt will be made in this section of the present paper to outline the principles involved with the aid of a few concrete examples. First the factors influencing the composition of the pollen record in the rocks will be analysed. Then the data from other disciplines, viz. botany, geology and zoopalaeontology, which permit a better understanding of microfloral changes, will be discussed, leading finally to the establishment of a zonation. The pollen spectrum, obtained by calculating the percentages in which the various species occur in a sample, is the end result of various factors which influence production and dispersal. Rev. Palaeobotan. Palynol., 6 (1968) 189 348
203
Primary factors control the presence of the plants which produced the pollen grains and spores, and secondary factors affect dispersal prior to fossilization.
Evohttionary change and migration Primary factors are evolutionary change and migration or increases and decreases in response to changes in climate or topography. Evolutionary change may obviously be expected to yield the most reliable criteria for the establishment of a time-stratigraphical framework of regional significance. Examples are the gradual development of Poaceae (Gramineae) and Asteraceae (Compositae), as reflected in the stratigraphical distribution of the corresponding pollen types. Since these are large and varied groups of plants with at present a virtually world-wide distribution, their first appearance and subsequent development have proved to be of wide time-stratigraphical significance. An example of evolutionary development on a subregional scale is the evolution of Sonneratia pollen types in the Indo-Malesian area. As will be discussed in detail later, it was possible here to trace morphogenetic changes within a single lineage. However, such cases are exceptional, and pollen and spore species generally appear fairly suddenly in the stratigraphical record without any indication of their phylogenetic origin. Unless coinciding with a hiatus in the stratigraphy, these relatively sudden appearances must have been caused by changes in the environment which enabled the parent plants involved to increase in numbers and extend their geographical range. The main factor of interest here is climatological. The problem of how to recognize the effect of changes in climate in the stratigraphical distribution patterns of the many species studied can be approached in a direct way by botanical identification of fossil pollen and spore types with living taxa, which have well-defined climatological tolerances. So far not much success has been achieved in this direction, since none of the identified lowland species discussed in this paper are known to be indicative of a specific climate except in so far as they are adapted to the tropical climate in general. However, it is sometimes possible, by reference to climatologically significant lithological changes, to detect the relative climatic requirements of certain fossil markers. Such a case was present in the Oligo-Miocene (Magnastriatites howardi Zone) of western Venezuela. Here a local accumulation of anhydrite in shales, contrasting strongly with coal-bearing underlying strata, was associated with a peculiar pollen flora not encountered elsewhere inthiscomposition. Here the inference of a climatological change towards greater aridity was possible. Another case in which a climatological cause may be detected is the rather sudden disappearance of certain pollen species. The extinction of Nypa-type pollen at the Eo-Oligocene boundary in Venezuela is approximately contemporaneous with a widespread increase in the incidence of mottled shales, indicating a change 204
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
to a climate with more pronounced seasonal rainfall. It is conceivable that such a change could have caused Nypa to disappear, since the plant at present is mainly restricted to the ever wet tropics in the Indo-Malesian area. The often rather sudden immigration of certain species may also have been caused by a change in climate which enabled the plants involved to extend their range. An example which could be explained this way is the rather sudden appearance in the Eocene of western Venezuela of Retitricolporites guianensis and Cicatricosisporites dorogensis. However, such phenomena may also be due to the development of new pathways of migration. A good example of this is the southward migration along mountain chains of montane elements such as Alnus. In Borneo this could be attributed to a mid-Tertiary phase of mountain building. In the Caribbean area the cooling of the climate at the beginning of the Pleistocene must have facilitated the migration of Alnus along existing mountain chains from the north. An analogous case is the dispersal across oceans of plants which are adapted to a coastal environment, such as mangroves. If such floral changes are considered for the definition of a regional zonation, the question of dispersal speed must be taken into account. Although little is known quantitatively from Recent plants, it must be assumed that differences in this respect exist and that they depend on factors such as adaptation and viability of the seeds. The conspicuously sudden appearance and subsequent rapid increase of Asteraceae (Compositae) pollen types in the Lower Miocene of northern South America, Nigeria and the Far East could reflect the adaptation to easy dispersal of Asteraceae seeds. In contrast one distinct case of delayed dispersal has come to light: Symphonia pollen appears earlier in the stratigraphical record in Africa than in South America and this obviously is a consequence of the difficulty of crossing the Atlantic Ocean. It will be clear that such cases can only be detected when independent dating is available, and they should of course not be utilized for the definition of a regional time-stratigraphical zonation. The majority of the floral changes observed on the distribution charts will, however, have been influenced to a varying degree by local facies factors. For instance, the varying abundance in which mangrove pollen occurs in the sedimentary record, once it has made its first appearance in the area, largely reflects the acreage covered by mangrove, which is determined by the local topography. It will now be clear that, if climatological and topographical influences are of restricted lateral extent, the interplay of the environmental conditions on the one hand, and the variable tolerances of different species on the other, combine to produce complicated stratigraphical distribution patterns in which time-stratigraphical correlation lines are not easily detected. Rev. Palaeobotan. Palynol., 6 (1968) 189-348
205
Dispersal of pollen grains and spores In addition, the secondary factors controlling pollen and spore dispersal may further obscure the patterns. The majority of the samples investigated are deltaic-marine silts, clays and shales, which means that the individual grains were generally transported, mixed, sorted according to size and possibly redeposited once or several times. Before giving a few examples of such complicated patterns, it is necessary to discuss the influence of the secondary factors in greater detail. Relatively soon after starting the investigation of Tertiary clastic sediments in the tropics, it was realized that the conventional picture of a fairly homogeneous pollen rain, failing impartially in various sedimentary environments, was inadequate for an understanding of the complicated stratigraphical distribution patterns encountered. Studies of Recent tropical sediments have since shown that, in a humid environment at least, water transport may be of far greater quantitative importance than wind transport (MULLER, 1959). In the dispersal picture which has now evolved all species pass initially through a phase of air transport. This phase may be of very short duration as, for instance, in tropical peat swamp forests, where most of the pollen produced by the trees was found to be deposited within a very restricted area. If the peat formed here is preserved in the geological record as coal, no further transport takes place, except when lumps of coal are later eroded and transported as pebbles. At the other end of the scale, the pollen grains and spores produced by the montane vegetation in the tropics are known to be transported in large quantities over considerable distances by high-altitude atmospheric currents. This is especially true of wind-pollinated trees such as Alnus, Pinus, and of certain ferns. Sooner or later, however, mainly depending on wind strength, turbulence and wash-out by raindrops, all pollen grains and spores land on the earth's surface. If they are not soon carried away by water, they are mostly destroyed by corrosion and escape fossilization. A different fate, of course, awaits that portion of the pollen rain which is caught in river systems or the sea. It makes a great difference whether further transport takes place by river systems or whether pollen grains and spores settle directly on the surface of the sea with further transport exclusively by sea currents. In the first case, a small proportion of the pollen gathered from the entire drainage area will be deposited in the alluvial and coastal plain sediments in the delta area, but most of it will be concentrated at the river mouth and discharged together with the sedimentary load into the sea. In this way concentrations of pollen in fluviomarine sediments close to river mouths are formed, such as have been found in front of the Orinoco delta (MULLER, 1959) and in the Gulf of California (CRoss, 1966). Size sorting will hardly be noticeable during this phase and tidal currents and turbulence will generally cause efficient mixing of the final 206
Rev. Palaeobotan. Palynol., 6 (1968) 189-248
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pollen suspension entering the sea. Also, the largest number of species will be present in the fluviomarine sediments. In the second case the composition of the pollen load is quite differently affected. First of all sea currents act as slow transporting agents over wide fronts with relatively less turbulence further offshore; the result is gradual settling and deposition of pollen grains and spores, accompanied by size sorting. Wind-transported pollen may be added and this may considerably modify the composition of the pollen load in areas far offshore. Another factor about which little is known is selective corrosion of pollen and spores during seaborne transport. One final complication has to be evaluated and this is the probability that not all pollen is travelling in a single move from anther to final resting place, but that temporary entrapment in sediments is followed by subsequent erosion and that renewed transport takes place. This recycling of pollen grains and spores may take place within what is geologically speaking an insignificant period of time, as is the case in the average delta, where meandering streams may erode sediments deposited only a short while before. Such recycling, of course, only increases the degree of mixing of the pollen load eventually supplied to the sea and does not affect stratigraphical distribution patterns to any appreciable degree. However, when the time lag between deposition and recycling becomes greater, serious difficulties may arise, culminating when older pollen-bearing formations are eroded in the source area of a river system. When a clear difference in preservation between such older reworked pollen grains and spores and autochthonous ones is present, they can be easily excluded from the pollen sum, but unfortunately this is usually the exception rather than the rule. Generally there is no clear-cut difference, and the presence of many slightly different corrosion patterns in one single sample may be the only clue indicating the presence of several generations of reworked pollen grains and spores. In such cases a detailed knowledge of the basic floral succession in the area of investigation may enable one to spot the scattered presence of anomalous pollen associations and to recognize them as reworked assemblages. Here general geological considerations, indicating the probable origin of the sediment particles have also to be taken into account. Recently VAN GIJZEL (1961) has demonstrated that fluorescence microscopy may be able to discriminate between autochthonous and reworked pollen. In the Palaeogene sediments of western Venezuela, for instance, reworked pollen was scarce because the bulk of the sediments deposited during that time had been derived from the Guiana shield, where no pollen-bearing sediments were eroded. In younger sediments the occurrence of reworked pollen of a Palaeogene age proved to be clearly related to distinct unconformities. In contrast, in the Neogene sediments of northwestern Borneo no such clear-cut unconformities exist and since the sediments had been recycled many times during the course of the Tertiary, a rather diffuse distribution of reworked Rev. Palaeobotan. Palynol., 6 (1968) 189-348
221
pollen was the result. It was not unusual to recognize in a single sample up to three different generations of reworked pollen and spores, which created considerable difficulties in the interpretation. This situation has practical consequences for the establishment o f a zonation, since the oldest occurrence of species obviously is more reliable than the youngest. In fact the regional zonation presented here is exclusively based on such oldest occurrences. However, when cuttings have to be investigated for routine purposes, the youngest occurrences may be of greater practical value.
Examples The practical application of the above principles will now be illustrated with a few examples. The first case refers to base Monoporites annulatus Zone in northern South America. Within the Eocene of western Venezuela, which was the first area investigated, two floral boundaries were apparent in approximately the same stratigraphical interval: aal well-defined increase in Echitriporites trianguliJormis and, slightly higher, a less conspicuous base of Monoporites annulatus. Later the absence ofEchitriporites trianguliformis in the Eocene of Colombia was noted. This absence could not be attributed to a stratigraphical hiatus or to a different climate, since the remainder of the floral assemblage proved to be essentially similar. However, the Colombian Eocene sediments are more terrestrial than those in Venezuela, and it became clear that Echitriporites trianguliformis was derived from a coastal plant with mainly waterborne dispersal of its pollen in seaward direction. This reduced its value for regional correlation and, since Monoporites annulatus appeared to have a wider distribution, because it was derived from a more inland environment, its increase in the Early Eocene both in marine and more terrestrial deposits is preferred as the regionally valid time-stratigraphical correlative horizon. The marked increase in Echitriporites trianguliformis retains, however, its practical correlative value within the restricted area of the Lower Eocene in the Maracaibo basin. In the case of the top in the occurrence of Proteacidites dehaani (Upper Cretaceous) it was soon apparent that this event could be recognized both in marine deposits in the northern Maracaibo basin and in alluvial plain deposits in Colombia and the southern Maracaibo basin. Regional time-stratigraphical value could, therefore, be assumed for this floral boundary. In both these examples botanical identification of the pollen species was impossible or did not provide sufficient evidence to permit an independent check on the environmental requirements of the parent plants. The method outlined above was the only feasible one for the recognition of time-stratigraphical value. In the examples from the Neogene, described below, on the other hand, this sort of conclusion is indeed supported by direct botanical evidence. 222
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
GEOLOGICAL
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ROCK-STRATiGRAPHICAL UNITS
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D POLLEN AND SPORE MARKER SPECIES
In the Oligo-Miocene the first increase in the Rhizophora pollen type (Zonocostites ramonae) can only be reliably observed in coastal and offshore marine sediments, while the approximately contemporaneous first increase in the Ceratopteris type (Magnastriatites howardi) can be detected in terrestrial environments as well. However, the small fresh-water ferns of the genus Ceratopteris can only flourish in open vegetation and will hardly occur under a closed forest canopy, which restricts the dispersal of the spores to water transport mainly. Ceratopteristype spores thus occur more regularly in inland environments, where Rhizophora pollen can be extremely rare, and therefore their oldest occurrence has been taken as the more reliable time-stratigraphical horizon. In practice of course both floral changes support each other and are used in conjunction. Another example from the Neogene of western Venezuela concerns the recognition within the same body of strata of three sets of correlation lines: (1) A topographically-influenced succession of mangrove dominance alternating with more inland vegetation. (2) A subregional succession, probably of a climatological nature. (3) A top occurrence of Cicatricosisporites dorogensis. The correlation lines derived from (1) cross at an angle those from (2), while none of these were observed in the adjoining fully marine succession. However, the top occurrence of Cicatricosisporites dorogensis proved to be recognizable regardless of environmental influence, and thus was judged to be of major timestratigraphical significance. In general the principle may be formulated that any palynological change which is paralleled by a facies change is of questionable time-stratigraphical value. if, on the other hand, the pattern of palynological changes crosses the environmental correlation lines derived from lithology or benthonic faunal distribution, then that pattern is likely to be of time-stratigraphical value at least within the area of study.
Statistical analysis of the palynological data In the absence of positive information from lithology, faunal or botanical affinities or climatic indications, statistical analysis of the palynological data can be developed into a powerful tool for interpretation. A first method is to measure the percentage variation, which is high in a terrestrial environment where pollen dispersal is restricted and low in a marine environment in which the pollen load has become thoroughly mixed. This variation is best measured by calculation of the standard deviation, for which a minimum of twenty samples is necessary. This calculation is, however, applicable only to common species. Secondly, an attempt can be made to separate statistically associations of species which have a common source area. For instance, if alluvial-plain deposits
Rev. Palaeobotan.Palynol., 6 (1968) 189-348
233
are being investigated, the percentages of the species inhabiting this environment will vary greatly, depending on the local edaphic factors, while species associations from outside this environment and transported into it in a better-mixed composition will always show a constant ratio. If successful, such a statistical analysis will enable the palynologist to separate, for instance, mangrove, river bank, peat swamp, alluvial swamps and marshes, upland and montane associations. The proportion in which these associations occur will then be mainly a function of the general topography of the source area as a whole, while any changes occurring within associations may have climatic or evolutionary significance and will be of greater time-stratigraphical significance. Association tests can be adapted for this approach. Thirdly, the variation in occurrence between rarer types is best measured with a run length test, which measures the variation in distance and length of series of single occurrences. To be reliable a minimum of 80 consecutive samples are needed for this test, which can also be applied to more common species when a minimum percentage truncation is chosen. All these statistical tests can be so devised that the significance of the results is expressed in probability values. One disturbing factor may be the presence of reworked pollen as erratic assemblages. For large numbers of samples, calculation by means of mechanical data processing is, of course, the only practical method of applying these statistical tests.
Summary of interpretation experience Summarizing twenty years of experience, it may be stated that for most cases tools are available which allow discrimination between local and regional events of time-stratigraphical value on the one hand and effects caused by time-crossing events such as transgressions and regressions on the other. This information then allows the establishment of a zonation adapted to the particular stratigraphical problem at hand. For short distances and short time intervals the effects of striking topographical events may provide the correlative framework; for correlation over larger distances climatological changes will produce the best means, while on an intercontinental scale correlation on evolutionary change appears to be the only reliable method. In general, however, the larger the distance, the more difficult it becomes to define and trace sharp floral boundaries. In particular boundaries defined on evolutionary change are notoriously hard to place accurately in thick continuouslydeposited sediments. This often poses a practical problem, since the geologist generally requires correlation lines, while the palynological events on which the zonation is based are by nature mostly gradual. In fact any sharp floristic boundary is more probably indicative of a hidden unconformity than of anything else. 234
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
It is worth ending this chapter by listing below a few more of the limitations encountered in applying palynological correlation methods. (1) Determinable pollen and spores absent or scarce. This may be due to: (a) original scarcity in sediments such as sands, conglomerates, limestones; (b) destruction by oxidation shortly after deposition, e.g., mottled clays; (c) destruction by oxidation after weathering of outcrops, common in the more arid parts of the tropics; (d) destruction due to high temperature effects caused by deep burial, volcanic activity, proximity of intrusions, heat generated by tectonic friction. (2) Statistical errors. These fall mainly under two headings: (a) the use of inadequate counts; (b) the use of an unsuitable selection of species which comprises the pollen sum, if percentage ratios are calculated. As regards (2a) the main practical problem is to achieve a maximum of results with a minimum count. In practice a count of 70-100 selected marker species with a sampling distance of 75-100 ft. has proved to be entirely adequate for the solution of most correlation problems. Here, the number of grains counted per sample has been sacrificed to the number of samples investigated. If more than one investigator is counting the same material, the influence of determination and counting errors should be eliminated by carefully designed counting schemes, which will average out individual errors. Errors grouped under (2b) are bound to influence the results especially when floral changes are indistinct, as in the case of thick sedimentary series deposited within a short interval of time, or when local influences in the pollen spectra obscure the occurrence of scarce regional marker species. Then it becomes imperative to test various percentage sums in order to arrive finally at the combination of species which, in their changing ratios, will reflect most distinctly the events of time-stratigraphical value on which the correlation will be based. This is an important point and it should be clearly understood that the percentage calculation system employed in the present study is adapted to the recognition of the zones described here. Other studies, for instance of a localized area in a restricted interval only, will start with a different pollen sum. In every area one of the principal problems in the early phase of developing a zonation in the extremely rich tropical Tertiary microfloras has been to decide which marker species to include in the pollen sum. Generally the marker species have been divided into two groups. Group A comprises all species which are of importance for the major regional zones, while group B contains those types whose fluctuations are of more local significance. Again one of the advantages of mechanical data processing is that this allows the rapid calculation, plotting and comparison of percentages based on different pollen sums.
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
235
ZONATION
The zones recognized in this paper are biostratigraphical units in the sense of the AMERICAN COMMISSION ON STRATIGRAPHIC NOMENCLATURE (1961). They are, therefore, not a priori to be considered as time-stratigraphical units and in fact some of the boundaries delimiting the zones probably are not contemporaneous over large distances. However, within the areas in which the zones are recognized, their succession is identical in all sections investigated. According to their lateral extent, the zones are grouped as follows: (1) pantropical zones; (2) transatlantic zones; (3) intracontinental zones. The definition and description of the zones will be documented by a restricted number of type sections, mainly taken from northern South America (Fig.l-14). The range chart (Fig.15) illustrates the ranges of all species discussed, based on evidence from a much larger number of sections. The independent dating of the zones is discussed in the section "Independent dating".
Pantropical zones The oldest pantropical zone recognized is the Proxapertites operculatus Zone characterized by the regular co-occurrence of Proxapertites operculatus, Proxapertites cursus, the Spinizonocolpites echinatus group, and Eehitriporites trianguliformis. Its base, which as yet could only be studied in Nigeria and Borneo, is provisionally defined by the qualitative base of the occurrences of Echitriporites trianguliformis and the Spinizonocolpites echinatus group. Further study is necessary to define and evaluate more accurately the base, which is probably of Senonian age. The zone is well-developed in the Rubio-road section (Venezuela) (Fig.3), well Egoli-1 (Nigeria) (Fig.9), and in the Lundu-Kayan section (Borneo) (MULLER, 1968). The transition to the overlying Monoporites annulatus Zone is marked by the first regular occurrence of Monoporites annulatus. This is not a sharply defined event, since the increase in Monoporites annulatus is rather gradual with alternating periods of higher or lower abundance. In the Rubio-road section (Venezuela) (Fig.3) the base of M. annulatus is rather well defined, but this is a stratigraphically condensed section. In well Icotea-I (Venezuela) (Fig.4), the increase is much more gradual. Since it is known that this well penetrates a very thick Eocene section without any marked gaps, the record shown here is probably a good reflection of the rather irregular increase in Monoporites annulatus in this part of the world. In Nigeria the M. annulatus Zone in the Ovim Bende section (Fig.ll) also shows a well-pronounced base, but in the Imo-river section (Fig.10) the base is less distinct. In Borneo the base has not yet been accurately fixed stratigraphically. M. annulatus is absent from all Upper Cretaceous and Paleocene sediments examined so far and is known to occur throughout the Neogene. Its base can, therefore, be expected within the Eocene there also. 236
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
The boundary with the overlying Verrucatosporites usmensis Zone is defined by the first occurrence of Verrucatosporites usmensis. However, there is a fairly wide interval in which transitional forms between Verrucatosporites usmensis and the presumed ancestral forms with a low verrucation occur. Moreover, there is evidence that the increase in number of Verrucatosporites usmensis takes place earlier in Nigeria than in the Caribbean area. Consequently this boundary is not a sharp one. In the Caribbean area the base in the occurrence of Cicatrieosisporites dorogensis appears consistently to be below the base of V. usmensis and serves as a useful additional criterion. In the Paz del Rio section (Colombia) (Fig.l), the Verrucatosporites usmensis Zone is thus characterized by regular occurrences of Cicatricosisporites dorogensis and scattered occurrences of Verrucatosporites usmensis. In the Ovim Bende and Imo-river sections (Nigeria) (Fig. 10, 11), the boundary between the Monoporites annulatus Zone and the Verrucatosporites usmensis Zone is sharply defined as these sections are incomplete, while in Benin West-I (Fig.12) the change is slightly more gradual. In Borneo the boundary has not been sufficiently studied as yet. The boundary between the Verrucatosporites usmensis Zone and the overlying Magnastriatites howardi Zone is marked by the first appearance of Magna-
striatites howardi. In the Paz del Rio section (Colombia) (Fig.l) this boundary is sharply defined, in Chafurray-3 (Colombia) (Fig.2) less so. In Benin West-1 (Nigeria) (Fig.12) a well-defined boundary ispresent, but in the Imo-river section (Fig.10) recognition of the Magnastriatites howardi Zone depends on a rare occurrence of M. howardi in one sample only. In Borneo the stratigraphical position of this boundary has still to be clarified. The boundary with the overlying Crassoretitriletes vanraadshooveni Zone is marked by the base of the regular occurrence of Crassoretitriletes vanraadshooveni. In Chafurray-3 (Colombia) (Fig.2), this boundary is weakly pronounced, but in B-188 (Venezuela) (Fig.6), a sharply defined base is present. In Okoloma-1 (Nigeria) (Fig.13), the base is rather well defined. In Borneo the base of the occurrence of Crassoretitriletes vanraadshooveni more or less coincides with the base of Florschuetzia levipoli and is slightly older than in the Caribbean area. The youngest boundary is the base of the Echitricolporites spinosus Zone and is marked by the base of the regular occurrence of Echitricolporites spinosus. In B-188 (Venezuela) (Fig.6) and in CO-85 (Trinidad) (Fig.7) the boundary is well defined. In Lubara Creek-2 (Nigeria) (Fig.14) the increase in Echitricolporites is gradual and fairly irregular, and the location of the boundary is, therefore, difficult to determine. Rev. Palaeobotan.Palynol., 6 (1968) 189-348
237
Transatlantic zones The pantropical Proxapertites operculatus Zone can be subdivided in the Caribbean area and in Nigeria into three transatlantic zones. The oldest is the Proteacidites dehaani Zone. This zone is characterized mainly by the co-occurrence of Proteacidites dehaani and Buttinia andreevi, together with high percentages of Foveotriletes margaritae. The boundary with the overlying Retidiporites magdalenensis Zone is taken at the top occurrence of Proteacidites dehaani. In the Rubio-road section (Venezuela) (Fig.3) this boundary is well defined. In Egoli-I (Nigeria) (Fig.9) the boundary is also rather well marked, mainly, however, by the decrease in Buttinia andreevi, which was absent in the previous section, although it is known to occur elsewhere in the Caribbean area within the zone. The Retidiporites magdalenensis Zone is mainly negatively characterized by the absence of Proteacidites dehaani and Buttinia andreevi. Foveotriletes maragritae is still fairly frequent, although it may diminish in abundance in the higher part of the zone. The zone is further characterized in both areas by the regular presence of Retidiporites magdalenensis, Echitriporites trianguliformis, and Proxapertites
operculatus. The boundary between the Retidiporites magdalenensis Zone and the overlying Retibrevitricolpites triangulatus Zone is marked by the first appearance of Retibrevitricolpites triangulatus, Striatricolpites catatumbus, and Psilatricolporites
crassus. In the Rubio-road section (Venezuela) (Fig.3) this boundary is clearly defined. In the Ovim Bende section (Nigeria) (Fig.l l) the boundary is also fairly distinct. In western Venezuela this boundary is further marked by the first appearance of Retitricolpites irregularis and the disappearance of Retidiporites magdalenensis, Proxapertites cursus, Bombacacidites annae, Ctenolophonidites lisamae, and Foveotricolpites irregularis. It is assumed that this pronounced floral change coincides with an unconformity. The pantropical Magnastriatites howardi Zone can further be subdivided both in northern South America and Nigeria into two transatlantic zones, the Cicatricosisporites dorogensis Zone and the overlying Verrutricolporites rotundiporis Zone. The boundary between these two zones is marked by the more or less simultaneous decrease in Cicatricosisporites dorogensis and increases in Verrutricolporites rotundiporis and in Zonocostites ramonae. In Chafurray-3 (Colombia) (Fig.2) this boundary is well marked, but in Benin West-1 (Nigeria) (Fig.12) only one sample was available, which could be assigned to the Verrutricolporites rotundiporis Zone, and the evidence here is not as strong. 238
Rev. Palaeobotan.Palynol., 6 (1968) 189-348
Preliminary results indicate that the major increase in Zonocostites ramonae in Borneo takes place roughly at an equivalent stratigraphical level. The other two marker species do not occur here.
Intracontinental zones Caribbean area In the Caribbean area the transatlantic Retidiporites magdalenensisZone can be subdivided into three units. The oldest unit is the Foveotriletes margaritae Zone, which is characterized by the co-occurrence of frequent Stephanocolpites costatus, Foveotriletes margaritae, Longapertites vaneendenburgi, and Gemmastephanocolpites gemmatus, and by the absence of Bombacacidites annae and
Ctenolophonidites lisamae. The boundary with the overlying Ctenolophonidites lisamae Zone is taken at the first occurrence of Ctenolophonidites lisamae and Bombacacidites annae, and this zone is further characterized by the regular presence of Gemmastephanoeolpites gemmatus, diminishing quantities of Foveotriletes margaritae, and the regular presence of Proxapertites cursus. The base of the youngest Foveotricolpites perforatus Zone is defined by the first occurrence of Foveotricolpites perforatus, which species is restricted to the zone. Bombacaeidites annae and Ctenolophonidites lisamae are frequent in this zone, while Stephanocolpites costatus, Foveotriletes margaritae and Gemmastephanocolpites gemmatus have virtually disappeared. This subdivision is clearly visible in the Rubio-road section (Venezuela) (Fig.3). The Monoporites annulatus Zone can be subdivided in the Caribbean area into four units. The boundary between the Psilatricolporites crassus Zone and the overlying Psilatricolpites operculatus Zone is taken at the lowest occurrence of Psilatricolpites operculatus, as visible in Icotea-1 (Venezuela), (Fig.4) and the Prevenci6n section (Venezuela) (Fig.5). The next higher boundary between the Psilatrieolpites opereulatus Zone and the Retitricolporites guianensis Zone is placed at the base regular occurrence of Retitricolporites guianensis. This boundary is present in the Prevenci6n section (Venezuela) (Fig.5). The Verrutricolporites rotundiporis Zone can be subdivided into the Jandufouria seamrogiformis Zone and the overlying Psiladiporites minimus Zone. The boundary between these two zones is marked by the base of the regular occurrence of Psiladiporites minimus, as is visible in B-188 (Venezuela) (Fig.6). The Crassoretitriletes vanraadshooveni Zone can be subdivided in northern South America into the Multimarginites vanderhammeni Zone and the overlying Grimsdalea magnaclavata Zone. The boundary between these two zones is marked by the base of the occurrence of Grimsdalea magnaclavata. This is clearly visible in B-188 (Venezuela) (Fig.6).
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
239
The Echitricolporites spinosus Zone can be subdivided into three zones. The boundary between the Pachydermites diederixi Zone and the overlying Echitricolporites mcneillyi Zone is marked by the base of the regular occurrence of Echitricolporites mcneilly. This boundary is distinct in CO-85 (Trinidad) (Fig.7) and Paria-1 (Venezuela) (Fig.8). The boundary between the Echtricolporites mcneilly Zone and the Alnipollenites verus Zone is placed at the base of the regular occurrence of A. verus. In Paria-1 (Venezuela) (Fig.8) this boundary is well developed.
Borneo In Borneo a local subdivision can be established, based exclusively on the evolutionary development within the genus Florschuetzia (Fig.16). The lowermost zone, FIorschuetzia trilobata Zone, is characterized by the presence of F. trilobata and the absence of younger forms. The zone probably covers the upper part of the Verrucatosporites usmensis Zone and the lower part of the Magnastriatites howardi Zone, but the stratigraphical position of its base has still to be determined precisely. The first development of Florsehuetzia semilobata and F. levipoli marks the base of the next higher Florschuetzia levipoli Zone, which coincides approximately with the weakly defined base of the Crassoretitriletes vanraadshooveni Zone. In this zone FIorsehuetzia trilobata decreases in numbers, while F. semilobata disappears. The average size of F. levipoli increases also from 30 /z to 35 /~. The overlying Florschuetzia meridionalis Zone is characterized by the regular presence of F. levipoli and, in increasing quantities, of F. meridionalis, while the average size of both species shows further increases. Florschuetzia trilobata is still present in the lower part of this zone, but disappears soon. The boundary between the Florschuetzia levipoli and Florschuetzia meridionalis Zones coincides approximately with the base of the Echitricolporites spinosus Zone, and the first regular occurrence of E. spinosus and Florschuetzia meridionalis can be taken as a criterion for its recognition. Both species have the disadvantage that in the very thick Miocene sediments of northwestern Borneo, their increase in number is gradual, which makes it impossible to recognize a sharp boundary.
INDEPENDENT DATING In the virtual absence of any age-indicating plant macrofossil evidence with which the palynological data could be correlated, associated animal fossils provide the only check on the age of the proposed zones. For this purpose most reliance has been placed on the age-indicating Foraminifera and, to a lesser extent, on 240
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
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the Mollusca. Not all areas investigated have produced a sufficient number of check points and it has also only rarely been possible to tie a floral change closely to a faunal change. In general, however, the available evidence indicates that the floral zones recognized are not markedly diachronous over the areas in which they are considered valid. The boundaries between the zones, however, can only rarely be sharply defined, and may not be exactly isochronous over larger distances. Future detailed studies will no doubt provide further evidence to narrow down the gaps in knowledge which still exist. In the account given below the floral zones will be discussed chronologically, a list being given of the age-indicating animal fossils, the faunal zones of which these are characteristic and, as far as possible, the standard time-stratigraphical units with which the zones are correlated. For the Palaeogene this is reasonably well established, but for the Neogene considerable uncertainty still exists, and no attempt will be made to relate the palynological zonation to the European stages. Instead the planktonic zonation established by BOLLI (1966) will be taken as yardstick and his subdivision in terms of Oligocene, Lower, Middle and Upper Miocene and Pliocene is adopted as a fair approximation. For Borneo reference is made to the well-known letter classification of Van der Vlerk and Umbgrove (ref. LIECHTI, 1960). Nomenclature of Foraminifera is according to LOEBLICH and TAPPAN (1964). It was not possible to present a full documentation for this part of the present paper, except for those sections shown for the purpose of defining the zonation and in which the occurrence of age-indicating fossils is recorded. However, in all other instances where a palynological zone is mentioned as associated with certain animal fossils, this is based on actual co-occurrence in the same sections.
(a) Proteacidites dehaani Zone In western Venezuela and Colombia this zone is associated with the smaller Foraminifera GIobotruncana gansseri, G. lapparenti, G. stuarti, Guembelitria eretacea, Siphogeneroides bramletti, and the ammonite Sphenodiscus sp. In Nigeria it is associated with the smaller Foraminifera Bolivina afra, Rugoglobigerina rugosa, and striate Heterohelix spp., with the ammonites Didymoceras sp., Libyoceras ismaeli and Sphenodiscus sp., and with the lamellibranchiat Inoeeramus sp. This faunal list clearly indicates a Maastrichtian age. So far no evidence of an older age has turned up, but since the lower limit of the Proxapertites opereulatus Zone has not been properly studied, the lower part of the Proteacidites dehaani Zone may of course be older than Maastrichtian. Unfortunately, both in Nigeria and in the Caribbean area, the top of the Proteacidites dehaani Zone is present in a predominantly coastal facies without 242
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
sufficient marine fossils, and, therefore, cannot be closely correlated to the top of the Maastrichtian. However, the presence in Nigeria of Danian fossils in the lower part of the overlying zone suggests that this top closely coincides with the top of the Maastrichtian.
(b) Retidiporites magdalenensis Zone The presence, in the lower part of the Retidiporites magdalenensis Zone of Nigeria, of the smaller Foraminifera Globigerina compressa and G. daubjergensis, which are markers for Stolk's Globigerina compressa range Zone, indicates a Danian age for part of this interval (SToLK, 1963). A slightly younger age is indicated by the presence in the higher part of the Retidiporites magdalenensis Zone in Nigeria of the smaller Foraminifera Globorotalia pseudomenardii, G. velascoensis and G. acuta, markers for Stolk's Globorotalia acuta/GIoborotalia velascoensis range zone, of Paleocene age. This and the fact that the lower part of the overlying Retibrevitricolpites triangulatus Zone still is of Paleocene age, indicates a Danian/Paleocene age range for the Retidiporites magdalenensis Zone. In Borneo a Paleocene age for part of the Proxapertites operculatus Zone is indicated by the presence of the smaller Foraminifer Globorotalia velascoensis and the larger Foraminifera Miscellanea miscella and Nummulites nuttalli.
(c) Retibrevitricolpites triangulatus Zone In Colombia the lower part of this zone is associated with the larger Foraminifer Actinosiphon barbadensis, indicating a Paleocene age. In Nigeria the lower part contains the smaller Foraminifera Globorotalia velascoensis, and G. acuta, also indicative of Paleocene, while in the higher part the smaller Foraminifera GIoborotaliaformosa and Globorotalia rex, which are markers for Stolk's Globorotalia.formosa range zone, indicate an Early Eocene age. In view of the fact that in Venezuela the overlying Psilatricolporites crassus Zone carries already a Middle Eocene fauna, while in Nigeria the overlying Monoporites annulatus Zone is associated with a Lower-Middle Eocene fauna, it is suggested that the Retibrevitricolpites triangulatus Zone ranges from Late Paleocene to Early Eocene in age.
(d) Monoporites annulatus Zone (not subdivided) In Nigeria this zone is associated with the smaller Foraminifer Cassigerinelloita amekiensis and associated planktonic Foraminifera indicative of Stolk's Cassigerinelloita amekiensis range zone of late Early-Middle Eocene age. In the Caribbean area a more detailed tie-in of the subdivision has been possible, and this will be discussed separately for each subzone below. Rev. Palaeobotan. Palynol., 6 (1968) 18%348
243
(e) Psilatrieolporites crassus Zone In Venezuela the lower part of this zone is associated with the larger Foraminifera Linderinafloridensis, Helicostegina gyralis and Lepidocyclina sp. A, while the upper part was found to contain Helicolepidina spiralis form C. According to VAN RAAOSHOOVEN (1951), these faunal associations indicate an early Middle and a late Middle Eocene age respectively.
(f) Psilatricolpites operculatus and Retitricolpites guianensis Zones In Venezuela these zones are associated with Helicolepidina spiralis form C and are, therefore, of late Middle Eocene age.
(g) Boundary Monoporites annulatus Zone/Verrucatosporites usmensis Zone Since the lowermost part of the overlying zone in Venezuela still is of late Middle Eocene age, this boundary must be situated in the Middle Eocene.
(h) Verrucatosporites usmensis Zone In Venezuela the presence in the lowermost part of Helicolepidina spiralis form C is still indicative of a Middle Eocene age, but for the upper part the larger Foraminifera Lepidocyclina pustulosa, Pseudophragmina mirandana, Nummulites striatoreticulata and Helicostegina soldadensis and, in Colombia the smaller Foraminifer Bulimina jacksonensis, indicate a Late Eocene age. In Nigeria the presence of the smaller Foraminifera Chiloguembelina martini and Truncorotaloides rohri, indicative of Stolk's Chiloguembelina martini-C. cubensis concurrent range zone, indicates a late Middle-Late Eocene age. The well-known Late Eocene mollusc fauna, originally described by Bullen Newton (ref. REYMENT, 1965) from the higher part of the Bende-Ameki Group, also falls within this zone. In the absence of any evidence of an Oligocene age, an age range for the Verrucatosporites usmensis Zone from Middle to Late Eocene, possibly including the earliest Oligocene, appears reasonable.
(i) Cicatricosisporites dorogensis Zone In the Caribbean area the presence of the smaller Foraminifera Globigerina ampliapertura, G. ciperoensis ciperoensis, Globorotalia opima opima and G. kugleri, and in Nigeria Globigerina ciperoensis ciperoensis, G. ciperoensis angulisuturalis and Globorotalia kugleri indicates an age range for the Cicatricosisporites dorogensis Zone spanning the interval Cassigerinella chipolensis/Hastigerina micra 244
Rev. Palaeobotan. PalynoL, 6 (1968) 189-348
Zone-Globorotalia kugleri Zone of BOLLI (1966). Accepting Bolli's age assignment of this interval, it is concluded that the Cicatricosisporites dorogensis Zone largely coincides with the Oligocene.
(j) Boundary Florschuetzia trilobata Zone/Florschuetzia levipoli Zone This well-marked boundary in Borneo was found to be situated at a level slightly above the boundary Tertiary e 1-4/Tertiary e 5 on a combination of evidence from larger and smaller Foraminifera. In the present paper the latter boundary is taken as coinciding with the Oligo-Miocene boundary, but it is realized that this needs further confirmation.
(k ) Jandufouria seamrogiformis Zone This zone is associated in the Caribbean area with the smaller Foraminifera
Catapsydrax stainforthii and Globigerinatella insueta, and approximately covers the Catapsydrax dissimilis, C. stainforthi and part of the Globigerinatella insueta Zones of Bolli (Lower Miocene).
(l) Psiladiporites minimus Zone In this zone the smaller Foraminifera Globigerinatella insueta, Globorotafia fohsi barisanensis, G. fohsi fohsi and Orbulina universa indicate that part of the Globigerinatella insueta, the whole of the Globorotalia fohsi barisanensis and part of the Globorotalia fohsifohsi Zones of Bolli are covered (Lower Miocene).
(m) Verrutricolporites rotundiporis Zone (unsubdivided) In Nigeria the presence of Globorotalia fohsi fohsi and Orbulina universa indicates that Bolli's Globorotalia fohsi fohsi, Globorotalia fohsi lobata and Globorotalia fohsi robusta Zones may possibly be covered, but since in the Psiladiporites minimus Zone of the Caribbean area no evidence of the latter two zones is present, it seems likely that in Nigeria only the Globorotaliafohsifohsi Zone is represented in the upper part of the Verrutricolporites rotundiporis Zone. Due to unsuitable facies conditions, the Globigerinatella insueta and Globorotalia fohsi barisanensis Zones have not been found in Nigeria.
Stratigraphic position of the base of Orbulina universa In view of the considerable importance which is generally attached to this datum, its location in the different areas will be discussed separately. In the Caribbean area, as well as in Nigeria and Borneo, it has been found to lie in the upper part of the Magnastriatites howardi Zone. In the Caribbean area
Rev. Palaeobotan.PalynoL, 6 (1968) 189-348
245
it can be pinpointed more closely and was found to lie in the Psiladiporites minimus Zone. In Nigeria it is present in the Verrutricolporites rotundiporis Zone, while in Borneo it was found in the middle part of the Florschuetzia levipoli Zone. In Bolli's scheme the base of Orbulina universa occurs in the upper part of the Globigerinatella insueta Zone.
(n) Multimarginites vanderhammeni Zone The presence of the smaller Foraminifera Globorotalia fohsi fohsi and G. fohsi Iobata is indicative of Bolli's Globorotalia fohsi fohsi and Globorotalia fohsi lobata Zones (Lower Miocene).
(o) Grimsdalea magnaclavata Zone This zone was found to contain the smaller Foraminifera Globorotalia fohsi robusta, G. mayeri and G. menardii and thus covers approximately the Globorotalia fohsi robusta, Globorotalia mayeri and Globorotalia menardii Zones of Bolli. The boundary between Lower and Middle Miocene would thus be present within the zone.
(p) Crassoretitriletes vanraadshooveni Zone (not subdivided) In Nigeria the presence of the smaller Foraminifera Globorotalia fohsi fohsi and Orbulina universa indicates a possible age range covering BoUi's Globorotalia fohsi fohsi, Globorotalia fohsi lobata and Globorotalia fohsi robusta Zones. This corresponds well with the more detailed evidence discussed under the two preceding Caribbean subdivisions of the Crassoretitriletes vanraadshooveni Zone.
(q) Florschuetzia levipoli Zone The age range of this Bornean zone is determined by the presence, in the lower part, of the smaller Foraminifer Globigerinatella insueta, indicative of Bolli's Catapsydrax stainforthi and Globigerinatella insueta Zones, in the middle part, of the larger Foraminifer Flosculinella bontangensis, indicative of Tertiary f 1, and of the smaller Foraminifera Globorotalia fohsi barisanensis, G. foshi fohsi and Orbulina universa, indicative of Bolli's Globorotalia fohsi foshi Zone, and, in the upper part, of Globorotalia fohsi lobata, G. fohsi robusta and G. menardii, indicative of Bolli's Globorotalia fohsi robusta and Globorotalia menardii Zones.
(r) Echitricolporites spinosus Zone (not subdivided) In Borneo the lower part of this zone carries the smaller Foraminifer Globorotalia menardii, indicating an age younger than Bolli's Globorotalia fohsi lobata 246
Rev. Palaeobotan. PalynoL, 6 (1968) 189-348
Zone, while in the upper part Pulleniatina obliquiloculata occurs, which is generally taken to indicate a Pliocene age. In the Caribbean area the latter Foraminifer is not found below the Echitricolporites mcneillyi Zone, suggesting that the Mio-Pliocene boundary may be close to the base of the last-mentioned zone. The youngest boundary in the Caribbean area, between the Echitricolporites mcneillyi and Alnipollenites verus Zones is, in view of the climatological interpretations, taken as closely coinciding with the Plio-Pleistocene boundary. Summarizing the results presented in the foregoing account, it may be stated that the top Maastrichtian, top Paleocene, top Lower Eocene, top Middle Eocene, top Upper Eocene and top Oligocene are well established in correlation with the palynological succession. The subdivisions in the Miocene up to the Mio-Pliocene boundary are less accurately known, mainly due to uncertainties remaining in the correlation of BOLLI'S (1966) planktonic zonation and of Van der Vlerk and Umbgrove's letter classification (re['. LI~CHTI, 1960) in the Far East with the standard European succession. On the general range chart (Fig. 15) the proposed correlation of the standard time-stratigraphical subdivision with the palynological subdivision is presented. Zones have been drawn approximately to an absolute time scale, derived from FUNNEL (1964). Two points should be mentioned here in connection with this chart. In the first place, the bases of the occurrences of Verrucatosporites usmensis and Crassoretitriletes vanraadshooveni have proven to be slightly diachronous, as discussed earlier. In the former case, the base occurrence in Nigeria has been taken as the lower limit of the Verrucatosporites usmensis Zone, while the timeequivalent horizon in the Caribbean area is approximately given by the base of Cicatricosisporites dorogensis. In the latter case, the base occurrence in the Caribbean area has been taken as the lower limit of the Crassoretitriletes vanraadshooveni Zone, since this is the best defined change in relation to the planktonic subdivision. Secondly, the detailed subdivision of the Eocene and Lower Miocene reflects local stratigraphical needs more than rapid floral change. The relatively long, unsubdivided Oligocene interval probably indicates lack of information due to a hiatus in the stratigraphical record of both the Caribbean area and Nigeria. In Borneo the Eocene interval has not yet been adequately investigated and no subdivision is possible at present.
STRATIGRAPHICAL APPLICATION
In this chapter the practical application of the palyno-stratigraphical evidence Rev. Palaeobotan. Palynol., 6 0968) 189-348
247
will be discussed and illustrated with three geological cross-sections from the Caribbean area (Fig.17-19). The sections chosen have been constructed as far as possible on the basis of wells or measured surface sections in which a fairly detailed palynological succession had been established. In a few cases a composite section had to be constructed by piecing together various scattered shorter sections, so that thicknesses of formations are consequently less reliable. Nomenclature of geological formations follows as far as possible generally accepted terminology. For Venezuela reference is made to the respective volume of the International Stratigraphic Lexicon (SCHWARCKANGLADE, 1956), for Colombia and Trinidad to more scattered literature. The environment of deposition has been broadly classified into three units: (1) upper coastal plain (fresh water), and more inland environments characterized by the absence of any brackish or marine faunal elements; (2) lower coastalplain (brackish water), deposits which may carry typical faunal associations indicating low and variable salinity; (3) marine. Section I (Fig.17) covers the Palaeogene from east-central Colombia to western Venezuela, running along the northern slopes of the Andes, circling around Lake Maracaibo to turn southwards along the Perija foothills as far as the Tarra area. A large part of the area covered by this section is underlain by marine Cretaceous deposits. The Colombian sections have not reached these, but in Venezuela the Col6n, Mito Juan and their lateral equivalent the La Paz Shales have been sampled and found to be restricted to the Proteacidites dehaani Zone. In the north a slightly younger marine deposit is the Guasare, covering the Foveotriletes margaritae and Ctenolophonidites lisamae Zones. The regression shown to have taken place by the change towards a transitional or even terrestrial environment has evidently not been contemporaneous, a phenomenon earlier described in a generalized way by KUYL et al. (1955). South of Lake Maracaibo, the sediments assigned to the Proteacidites dehaani Zone were already deposited in part in a transitional environment, as indicated by the Umir in Colombia and the lower part of the Orocu6 in Southwestern Venezuela. Further north in the Dibujo area (Riecito Mach6), the change from marine to terrestrial deposits takes place at the base of the Foveotricolpites perforatus Zone. The effect of tectonic movements during the Paleocene is also clearly visible. The interval Foveotriletes margaritae Zone-Foveotricolpites perforatus Zone is thickest in the Lebrija section and shows very regular thinning to the south and northeast. Along the Andean foothills (Fig. 17, columns 3-7) and in the northern Lake and Concepci6n areas (columns 8-10) the Paleocene has been truncated, indicating a minor orogenic phase separating Paleocene from Eocene. This truncation is least noticeable in the Riecito Mach6 section, where the possibility of continuous 248
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
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sedimentation is not excluded, although the rather sharp and distinct floral change at the base of the Retibrevitricolpites triangulatus Zone still suggests the presence of a hiatus. It increases southwards since, in Concepci6n, the Foveotricolpites perforatus Zone is missing, while in the North Central Lake area the Ctenolophondites ilsamae Zone is also missing, and it reaches maximum values along the northern Andean foothills. In Rio Mullapas and Rio Perdido the Proteacidites dehaani Zone is found underlying the Eocene, and the whole Paleocene appears to be missing. In a southwesterly direction the magnitude of the hiatus rapidly decreases again and in Quebrada La Mora the Foveotricolpites petforatus Zone is found again. Further south and in the Tarra area the top of the Paleocene interval coincides with the base of the Mirador Sandstone, and it is likely on geological grounds that a minor unconformity is present at this level (ScHAuB, 1948, p.225), coinciding with the base of the Retibrevitricolpites triangulatus Zone. In Colombia sampling gaps around this level preclude any definite statements on this problem. The Eocene sedimentation cycle starts with the Retibrevitricolpites triangulatus Zone. (As mentioned in the previous section of" this paper the lowermost part of this zone may be of Paleocene age.) Sediments assigned to this zone are thickly developed in the northeast and in Colombia, but they are absent along the northern Andean foothills between Rio de Oro and Rio Mullapas. The next higher Psilatricolpor#es crassus Zone is absent between Rio Perdido and Rio de Oro and in the Colombian sections. The overlying Psilatricolpites operculatus Zone is generally rather thin and its absence in sections with reduced sedimentation such as Rio Mullapas and Quebrada La Victoria may be due to sampling gaps. In contrast to the rather restricted areal distribution of the older Eocene zones, it is clear that the overlying Retitricolporites guianensis and especially the Verrucatosporites usmensis Zones have a much wider distribution. The former is thickly developed in the Rio Mullapas and Rio Lebrija sections, while the latter is found in more or less uniform thickness m all the northern Andean foothills sections as well as in T~ichira. The absence of one or both zones in Rio Mullapas, North Central Lake and Concepci6n is due to truncation by the well-known post-Eocene unconformity. From these observations it may be deduced that during the Eocene progressively younger sediments transgressed over an eroded Paleocene surface, first localized in the deeper parts of the sedimentary basin, but rapidly transgressing over virtually the whole area of investigation in the upper part of the Retitrico# porites guianensis Zone and especially during the time of deposition of the Verrucatosporites usmensis Zone. This last transgressive phase coincides with the widespread deposition of the marine Pauji in the east, which sharply contrasts with the transitional environment prevalent in the older Eocene. It must be noted that in the southwestern part this transgressive younger Eocene rests unconformably on Lower Eocene sediments of Retibrevitricolpites triangulatus-Psilatricolporites crassus Zone age, indicating a minor orogenic phase, Rev, Palaeobotan. Palynol., 6 (1968) 189-348
263
probably resulting in a slight subsidence accompanied by a southwestern tilt of the depositional basin. Thus in Quebrada La Mora the Verrucatosporites usmensis Zone is resting on the Ctenolophonidites lisamae Zone, in Rio de Oro on the Foveotricolpites perforatus Zone and in the Rubio road section already on the Psilatricolporites crassus Zone. In general Eocene sedimentation was thickest in the northeast, as shown by the Catanejo-Prevenci6n section. Continuation of the Eocene sedimentary basin towards Falc6n is likely, but no palynological data are available from this area due to carbonization of plant material. At this point it may be mentioned that, although the strong vertical exaggeration of the section suggests the presence of marked angular unconformity at many places, in reality this can hardly ever be observed in the field. Moreover, the similar lithologies of the formations on both sides of the unconformities and the absence of other age-indicating fossils made it virtually impossible to unravel the geological history in detail before the advent of palynological studies (cf. SCHAUB, 1948; MENCHER et al., 1953). The situation was further complicated by the presence of various sandstone bodies, which had been correlated merely on lithological similarities supported by weak photogeological evidence. The three main sandstone bodies are the La Sierra in the northwest, the Misoa in the southeast and the Mirador in the southwest. Palynological studies revealed that the bulk of the Mirador Sandstone had been deposited in the interval Retibrevitricolpites triangulatus-Psilatricolporites crassus Zone and was, therefore, roughly contemporaneous with the C-sand group of the Eocene terminology used in the Lake Maracaibo area, while both the La Sierra and Misoa Sandstones are mainly deposited in the interval upper Psilatricolporites crassus-Retitricolporites guianensis Zone, thus being markedly younger and equivalent to the B-group of sands in the Lake area. In addition, as already pointed out by SCHAUn (1948,p.224), the Mirador Sandstone cannot be traced in the field along the northern Andean foothills beyond T~ichira, and earlier attempts to do so were based on miscorrelation either with underlying Paleocene sandstone bodies equivalent to the Barco Sandstone member or with basal Upper Eocene sandstones transgressing over the eroded Paleocene surface. As can be seen on section I in the area between Rio de Oro and Rio Perdido, (Fig.17), due to the considerable gap shown to be present by palynology, these sandstones are close together and can easily be confused in the field or by photogeology. A further complication is present in the Tarra area southwest of Lake Maracaibo, where the onlapping La Sierra Sandstone comes into contact with the underlying Mirador Sandstone. It has been shown by palynological dating that in some areas, Quebrada La Victoria for example, the uppermost part of what had been called Mirador Sandstone is in fact the age-equivalent of the lowermost La Sierra Sandstone and that locally a minor hiatus may thus exist in the upper part of the Mirador. 264
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
These observations also have some consequences for the stratigraphical terminology. First of all, the boundary between the Carbonera and the Orocu6 Formations is distinct only when these formations are separated by the Mirador Sandstone, as is the case in T~ichira and the Tarra area. However, the disappearance of the Mirador in a northeasterly direction along the Andean foothills and the similar facies of the Orocu6 and Carbonera make it virtually impossible to separate these formations in the field. On the section the boundary between the formations has in such cases been taken to coincide with the stratigraphical hiatus revealed by palynology and indicated with a dotted line. Similarly the lithological separation of the Mirador and La Sierra Sandstones in the area of overlap is difficult, and recognition of these different sandstone bodies may only be possible when shale intercalations carry sufficient pollen for dating. Recently GONZALEZ(1967) has studied the transition Los Cuervos-Mirador in the Barco area (Colombia). He reports the presence of Cicatricosisporites dorogensis rather low in the Mirador Sandstone, which suggests that a relatively large part of this formation can be assigned to our Verrucatosporites usmensis Zone. However, the lack of data from the upper 100 m of the Mirador Sandstone, the absence of Retitricolporites guianensis and Perisyncolporites pokornyi, several other anomalies in the floral succession and the rather restricted number of samples of unknown quality preclude a more definite interpretation of his results. The final phase of Eocene sedimentation, where preserved, indicates general regression of the sea. In the Catanejo-Prevenci6n area the marine-deltaic Eocene sediments are succeeded by the continental La Victoria Formation. In the area between Rio Lebrija and Rio Perdido the Esmeralda and Carbonera Formations show no sign of transgression and in the Paz del Rio section the transitional San Fernando Formation, which is roughly time-equivalent to the marine Pauji transgression phase, is succeeded by the Oligocene continental Margua Formation. The regression here has taken place during the time of deposition of the Cicatricosisporites dorogensis Zone and is, therefore, younger than in the CatanejoPrevenci6n area where the La Victoria Formation is restricted to the Verrucatosporites usmensis Zone. In the Rio de Oro and Rio Perdido sections the Le6n Shale at the transition between the Verrucatosporites usmensis and Cicatricosisporites dorogensis Zones indicates a localized more pronounced subsidence, without marine influences. Section II (Fig.18) covers the older Neogene part of the stratigraphical succession and runs from the western Llanos area in Colombia to southwest Venezuela, crosses Lake Maracaibo and traverses Falc6n from west to east. The top of the San Fernando Formation, which in most sections can be found around base Cicatricosisporites dorogensis Zone, appears in the Rio Cubug6n to lie close to the top of the zone, thus indicating that the Le6n Shales of the La Fria area may be a lateral equivalent of the upper part of the San Fernando. In Rev. Palaeobotan. Palynol., 6 (1968) 189-348
265
Falc6n marine deposits characterize the Cicatricosisporites dorogensis Zone, while in well B-188 no evidence of the occurrence of this zone could be found. Possibly the barren Icotea Formation represents this interval. In the south the period of deposition of the San Fernando and of the Le6n Formations is followed by a regressive period, starting earliest in Voragine-l. No trace of this regression can be detected in Falc6n. Then, approximately in the middle of the overlying Verrutricolporites rotundiporis Zone (Jandujburia seamrogiformis Zone, upper part), a rather pronounced transgressive phase can be discerned. This is the well-known La Rosa transgression from the Bolivar coastal area of Lake Maracaibo, which can be followed from the marine Agua Clara in Falc6n, via the La Rosa of the Maracaibo basin, towards the Uracil fossil horizon of La Fria, which here occurs intercalated in the terrestrial Guayabo Formation. In Colombia this transgression is visible as a marine intercalation in the lower part of the Cubug6n Formation of the Rio Cubug6n and in the lower part of the Chafurray in well Chafurray-3. Voragine-I was situated more inshore and no marine interval occurs here. It has already been pointed out by Scr~atm (1948) and MENCHER et al. (1953) that this La Rosa transgression is nowhere connected with any disconformity. Its contemporaneity shows that during a short time a continuous seaway was present from east Falc6n as far south as Chafurray-3 in the Colombian Llanos. In the upper part of the Verrutricolporites rotundiporis Zone (Psiladiporites minimus Zone) a regression took place which can be recognized from the south as far as north central Falc6n in the transitional-continental deposits of the Chafurray, Caja, Cubug6n, Guayabo, Lagunillas and Cerro Pelado Formations, respectively. In the south, only in the Rio Cubug6n, a second transgression is indicated in the Multimarginites vanderhammeni Zone, which may be connected with the marine Querales Formation of north central Falc6n. In younger zones regressive deposits predominate. Only in Falc6n does marine influence persist. While in north central Falc6n the marine environment has been interrupted twice during the Neogene by regressive phases, in east Falc6n sedimentation was continuously marine, which made it possible to arrive at an accurate tie-in between the palynological zonation and Bolli's subdivision on pelagic Foraminifera. Unfortunately the east Falc6n stratigraphical sequence is based on a combination of scattered short sections and stratigraphical thicknesses shown are, therefore, probably not more than rough minimum estimates. As already mentioned, in contrast to the preceding Palaeogene section, no pronounced unconformities could be detected in the Neogene sediments investigated. Still, rather strong variations in thickness are obvious. In Colombia the section penetrated by Chafurray-3 is much more reduced than in Voragine-1. In Rio Cubug6n it is again slightly thicker than Voragine-1, but in the La Fria and Catatumbo areas maximum thicknesses are observed. Remark-
266
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
able are the extremely reduced thicknesses observed in B-188, especially since the floral succession appears complete, without any marked gaps. Thicknesses increase again rapidly, approaching the Falc6n basin, where, in north central Falc6n especially the Verrutricolporites rotundiporis Zone is excessively thick. This second section shows again the great value of palynology as a means of correlating from the marine facies, as present in Falc6n, to the mainly continental environment in southwestern Venezuela and the adjoining part of Colombia. The correlation of the various formations shown on both sections closely corresponds, for the Maracaibo basin, with the correlation chart presented by MILLER et al. (1958). In section III (Fig.19) the stratigraphy of the younger Neogene deposits is traced from northwestern Colombia to Trinidad. Three separate sedimentary basins are represented. In northwestern Colombia an investigation has been made of the area between Sinu and Bayunca, which is separated from the southern Maracaibo lake and Falc6n basin by the Perija mountain range on the border between Colombia and Venezuela. The latter basin is in turn separated from the eastern Venezuela-Trinidad basin by the mountains connecting the M~rida Andes with the coastal range of Venezuela. In these mountainous areas the youngest Neogene deposits have never been present or were eroded during uplift. In view of this geographical separation, the section is best discussed from west to east. In northwestern Colombia the marine sediments in the Sinu basin and near Bayunca are correlated by the Pachydermites diederixi Zone. The total interval covered by these two sections gives a complete succession from the Multimarginites vanderhammeni Zone to the Alnipollenites verus Zone. These isolated marine deposits in northwestern Colombia are correlatable with terrestrial sediments in the southern Lake Maracaibo area. In well Catatumbo-1 the Grimsdalea magnaclavata and Alnipollenites verus Zones can be recognized, but not the boundary between the Pachydermites diederixi and Echitricolporites mcneillyi Zones, which is due to an unfavourable mottled clay facies and to lack of samples. In general sediments are thicker in this area than in northwestern Colombia, and especially in the Rio Buena Vista section the younger zones reach considerable thickness. In contrast, sediment thickness in the older interval Jandufouria seamrogiformis Zone-Multimarginites randerhammeni Zone remains fairly constant, irrespective of facies, as shown by the correlation of Catatumbo-1 with the Rio Onia and Rio Buena Vista sections. This increase in thickness of the youngest sediments in the southern Maracaibo basin is a reflection of tectonic events connected with the approximately contemporaneous rise of the M&ida Andes. As already shown in section II, the younger Neogene sediments in the southern Maracaibo basin are continuous with those in Falc6n, but this sedimentary area was probably separated by a broad land area from the east Venezuelan basin. However, the floral characteristics marking the palynological zones turn UP
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
267
in the same sequence and in a virtually identical expression in both areas, and correlation between the marine Falc6n sequence and well OG-2, where a regressive sequence is present, presents no difficulties. From OG-2 to Trinidad the floristic boundaries again cross facies lines, and in the Catshill-Ortoire area a second tie-in with the zonation on age-indicating pelagic Foraminifera confirms the time-stratigraphical value of the palynological zonation. The younger part of the sedimentary sequence in Trinidad shows rapid changes in thickness and facies over short distances and palynology has been of great value here for unravelling the complex geological history. Of special interest is finally the great thickness attained by the Grimsdalea magnaclavata Zone in the Catshill-Ortoire area of Trinidad. This, together with the presence of large quantities of reworked material and the well-known Lengua boulder beds, reflects the final upward movement of the Andean orogeny, resulting in the upthrust of the Trinidad central range. Of course subdivision of the main floral zones presented here will make it possible to refine considerably the stratigraphical picture presented. This, however, lies beyond the scope of this paper, which was aimed primarily at demonstrating the value of palynological subdivision for regional correlation. Summarizing the results obtained so far, it may be stated that palynological evidence has: (1) shown the presence and magnitude of previously unsuspected stratigraphical gaps; (2) produced positive evidence for correlation of many Tertiary formations lacking age-indicating animal fossils; (3) shown that pollen boundaries can cross facies boundaries and are then eminently suited for palaeogeographical reconstructions. BOTANICAL RESULTS
Although the primary purpose of the palynological studies described here has been stratigraphical, the desirability to relate as far as possible the fossil pollen and spore species to Recent plants has, of course, produced some interesting botanical results. In this section of the present paper the most important results in this respect will be briefly discussed. First of all, the criteria applied in botanical identification must be evaluated. In general three categories were distinguished: (1) Fossil species of which the botanical affinity is wholly obscure, e.g., Buttinia andreevi. Possibly many of these species represent pollen or spores produced by extinct plants. (2) Fossil species which can be referred to more than one, not closely related, groups of plants, while ecological evidence is insufficient to decide which group may have been the parent plant, e.g., Striatricolpites catatumbus. 268
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
(3) Fossil species which, because of some unique morphological feature and corroborative ecological evidence, can be confidently assigned to some Recent plant taxon, e.g., Verrutricolporites rotundiporis, derived from Crenea sp. (Lythraceae). In the account given below only the species of category (3) will be discussed. Within this group it may be possible to assign the fossil species to a single taxon, as in the example given above, or the pollen or spore type under discussion may characterize more than one related taxon, e.g., Multiareolites formosus, which pollen type occurs in at least nine genera of Acanthaceae. In the former case it appears justified to use the term Crenea pollen as equivalent to the form species Verrutricolporites rotundiporis. In the latter case the fossil form species can also be referred to as Justicia-type pollen, one of the genera showing the pollen type being selected as indicator. Again the term Justicia type is equivalent to the form species Multiareolites formosus. Only the names of form species and form genera have, of course, taxonomic status.
FILICALES PARKERIACEAE
Ceratopteris ( Magnastriatites howardiJ The source areas of this spore species are the alluvial plain and coastal swamps where the parent plant grows in the shape of a small aquatic fern in shallow water, bordering lakes and river banks. This environment is characterized by rapid local facies changes and this is clearly reflected in the pronounced quantitative fluctuations in fossil coastal plain sediments. In marine sediments the spores are much rarer. The taxonomic identification is thus well supported by the distribution pattern of the fossil spore. The frequency of Ceratopteris spores in the Neogene of all three areas investigated and their absence in older Palaeogene and Cretaceous deposits, shows that the present-day pantropical distribution of this freshwater fern may date only from the mid-Tertiary. This is, however, somewhat in contrast to the isolated systematic position and specialized morphology of the genus, which is assumed to be of great antiquity. Its origin may have been local, but as long as no ancestral spore forms have been found this problem remains unsolved. SCHIZAEACEAE
Mohria type ( Cicatricosisporites dorogensis) This spore type is found in most of the species of Mohria and a few of Rev. Palaeobotan. Palynol., 6 (1968) 189-348
269
Anemia (Schizaeaceae). Without further study specific determination is impossible. The spores of this group are, however, clearly distinct from those produced by ferns of the genus Ceratopteris (Parkeriaceae). The Tertiary distribution of the Mokria type can best be discussed in conjunction with what is known of the Cretaceous distribution pattern of their nearest relatives. This discussion refers to the genus Cieatricosisporites s.l., recognizing the considerable difficulties which crop up when specific distinction of the dispersed spores is attempted (cf. HU~HES and MOODY-STUART, 1966). In the Caribbean area the Mohria type is absent from the uppermost Cretaceous, Paleocene and Lower Eocene but MULLER (1966) reports its presence in Cretaceous-Paleocene strata in northeastern Brazil. In the Middle Eocene the ferns producing this spore migrated into northern South America, as shown by its remarkably sharply defined base occurrence in Venezuela. It then remains fairly abundant up to the Oligo-Miocene transition. In the Miocene it virtually disappears from the record. In tropical west Africa it is common in the Albian-Senonian, absent in the remainder of the Cretaceous, and returns in the Upper Eocene, somewhat later than in the Caribbean, but suffering a sharp decrease in the Caribbean at the top of the Oligocene, and disappearing completely at the same level in Nigeria. In Borneo the spore type is abundant in the Lower Cretaceous, decreases in the Upper Cretaceous and becomes very rare in the Tertiary. As is well known, in Europe the type is frequent in the Cretaceous and in the Palaeogene, is still locally abundant in the Oligocene and disappears from the record in the Neogene (cf. KRUTZSCH, 1957). DRUGG (1967) has recently reported its presence in Late Cretaceous Paleocene strata from California. The Recent genera Anemia and Mohria are at present confined to the tropics and subtropics of America, the West Indies, southern and eastern Africa, Madagascar and the Mascarenes, where they occur often in a semi-arid habitat (CHRIST, 1910). From these data it is clear that the group as a whole has had a rather chequered history. In the Early Cretaceous it had a virtually world-wide distribution, but in the Late Cretaceous a contraction of its area occurred. In the Middle Eocene a second expansion of its geographical area took place in Nigeria and in the Caribbean, but the decline at the end of the Oligocene appears to have been world-wide again, leading to the present scattered relic areas of occupation in America and Africa.
Lygodium microphyllum type (Crassoretitriletes vanraadshooveni) Lygodium microphyllum is a climbing fern, common in the humid marsh and swamp forests of west Africa and the Indo-Malesian area, but absent today 270
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
in South America. The geological record of the Lygodium microphyllum type indicates rapid pantropical expansion in the Neogene. In the Caribbean area the fern apparently became extinct in the Miocene. The reasons for this rapid expansion and local extinction are entirely obscure. No ancestral spore type is known, but may be present in the insufficiently studied Eocene sediments of the Indo-Malesian area, where the type occurs slightly earlier and may probably increase more gradually during the Neogene than in Africa or in the Caribbean area. The high values of this spore type observed in the latter areas have not been found, however, in the Neogene of Borneo, which is rather in contrast to its present-day abundance in vegetationally disturbed areas and in coastal swamp forests.
ANGIOSPERMAE POACEAE (GRAMINEAE) ( Monoporites annu/atus)
The present-day abundance of grass in the tropics is largely confined to more open vegetation such as is found in coastal savannah's, river valleys, montane areas and in the Caribbean area above all in the Llanos plains. In general a drier climate with marked rainy seasons favours the development of extensive grass areas more than a humid one. The absence of grass pollen in Cretaceous and Paleocene sediments of the tropics, its first occurrence in low percentages in the Eocene and the increase in abundance in the Neogene probably reflect the gradual development of the Poaceae. According to GOTHAN and WEVLAND (1964), the family has been recorded from the Cretaceous of the present-day temperate areas on macrofossil remains. However, DRtJC~ (1967) confirms the absence of grass pollen for the Upper Cretaceous-Paleocene of California. The development of grass vegetation in the present-day tropics may, therefore, have been somewhat later than in the temperate areas. Although specific and generic determinations are hardly possible, it is likely that the increase in quantity of Poaceae pollen occurred simultaneously with an increase in taxonomic variety. The significance of grass pollen for the Tertiary stratigraphy varies according to the area. In Borneo short-lived increases could tentatively be related to phases of igneous activity in the hinterland, resulting in ash showers which may have temporarily destroyed the forest cover of large areas. Any evidence for widespread occurrence of savannah's is lacking in this humid area. In Nigeria major fluctuations in the grass curve probably reflect the shifting boundary between forest and savannah in the lowlands. The greatest abundance of grass pollen has been found, however, in the Caribbean area. Here open vegetation with a dominantly grass-covered soil must
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have been widespread in the Neogene, just as it is today. Source areas may have been the ancient Llanos, coastal savannah's, or alluvial plains in river valleys, such as described by WYMSTRA (1967) from the Magdalena valley in Colombia. That large amounts of grass pollen are produced in such environments is clear from the diagrams presented by WYMSTRA and VAN DER HAMMEN (1966) and WYMSTRA (1967). Transport of pollen could be by river or by air currents. The fact that in Recent Orinoco delta sediments grass pollen proved to be scarce (MULLER, 1959) is due to the dominance of swamp vegetation lacking in grass in the delta area proper. Since human interference can be excluded in the Mio-Pliocene, this is an indication that open vegetation rich in grasses may be originally of entirely natural origin in the tropics, although its wide expanse nowadays is largely caused by man, a conclusion also drawn by WYMSTRA and VAN DER HAMMEN (1966). A parallel development may be seen in the mid-continent area of North America, where the wide expanse of grassy plains is generally also supposed to date from the Neogene. ARECACEAE(PALMAE)
Nypa (Spinizonocolpites baculatus, S. ech&atus) Of this genus, at present restricted to the mangroves of the Indo-Malesian area, a fairly extensive fossil record of both fruits and pollen exists (ref. TRALAU, 1964; MULLER, 1964). The origin of Nypa must be sought in the Upper Cretaceous, since the ancestral pollen type Spinizonocolpites baculatus proved to be present already in the Senonian of all three areas investigated. In Sarawak the earliest records date probably from the post-Turonian (MULLER, 1968). Neither place of origin nor pre-ancestral type are known as yet. It would appear that Nypa early reached a pantropical distribution, which it maintained during the Paleocene and Eocene. The widest extension of range to the north took place during exceptionally warm phases in the Eocene, when it grew along the Tethys shores, as testified by the presence of fossil pollen and fruits. The occurrence of fossil Nypa fruits at latitude 52°N in the London Clay has recently been discussed by VAN STEENIS (1962a,b), who believes them to represent allochthonous drift material, and by TRALAU (1964), who considers the fruits to have been of local origin. This problem is connected with the evaluation of the climate as derived from the well-known London Clay flora. Although the palynological evidence presented here has no direct bearing on this controversy, it may be pointed out that the pantropical occurrence of Nypa in the Eocene makes it likely that it grew at least along the southern shores of the Tethys sea, which, during the warmest phase of the Eocene would certainly have been hot enough for Nypa to grow there. It then remains to be decided by further micro- and macro272
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botanical investigation whether the European fossil fruits were derived by drift from the southern Tethys shore or grew locally for a short time also on the northern shores. The disappearance of Nypa from the Tethys area has probably been caused by decreasing temperature, but the disappearance at the end of the Eocene, both from the Caribbean and Nigeria, as shown by the pollen record, is more difficult to explain. Possibly an increase in aridity, coupled with the development of a more pronounced seasonal climate, may have been operative. BETULACEAE
AInus (Alnipollenites verus) Identification of AInus pollen grains in tropical deposits is always a striking event for a palynologist familiar with temperate floras. The stratigraphical distribution of Alnus pollen in the tropics has clearly been proved to be related to the presence of mountains of sufficient dimensions to provide the temperate climate required and to the connections with more northerly mountain ranges which provided migration routes. In Borneo Alnus pollen was found to be abundant in Oligocene-Lower Miocene sediments associated with a mid-Tertiary orogenic phase. Its gradual decrease in quantity during the course of the later Miocene and Pfiocene could be related to a gradual levelling of the mountains (MULLER, 1966). Immigration must have been from the north in the Palaeogene. In Nigeria Alnus has not been recorded, no doubt due to the absence of suitable north-south mountain connections in the western part of Africa. In the Caribbean area the fairly sudden appearance of Alnus pollen in sediments of Pleistocene age is evidence of the fairly recent immigration of the genus into the Southern Hemisphere, where it occurs at present at altitudes above 1,000 m in the Andes as far west as the coastal range of Venezuela and as far south as Peru. Its migration from the north over the comparatively low mountain ranges of the--by then closed--Panama isthmus was certainly facilitated by the first colder phase of the Pleistocene. PROTEACEAE
Guevina type (Proteacidites dehaani) The presence of this pollen type in Senonian sediments of Nigeria and the Caribbean would indicate a formerly more extended area of certain genera of Proteaceae nowadays mainly restricted to the Southern Hemisphere (Guevina and Lomatia in Chili, Leucospermum in South Africa, Lomatia, Cardwellia and Steno-
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carpus in Australia). It is noteworthy that neither the Guevina type nor any other proteaceous pollen type was found in the Upper Cretaceous and Paleocene of northwestern Borneo (MULLER, 1968). On the other hand, closely related proteaceous pollen was described by BRATZEVA(1965)from the Upper Cretaceous of eastern Siberia and by ANDERSON (1960) from the Upper Cretaceous of New Mexico. These observations would suggest that certain Proteaceae had been able to migrate along the Pacific coast of South and North America, as far as eastern Asia. Their subsequent disappearance from this area must then have taken place at the Cretaceous-Tertiary transition.
OLACACEAE
Anacolosa type (Anacolosidites cf. luteoides) The form genus Anacolosidites may, according to ERDTMAN(1952), comprise pollen derived from the genera Anacolosa, Cathedra and Ptychopetalum (Olacaceae). The first-mentioned genus has a predominantly lndo-Malesian distribution (19 spp.) with only one species (A. unc~fera) described from central Africa and one from Madagascar. The other genera occur in Brazil (Cathedra, 5 spp.) and in tropical America and west Afl'ica (Ptychopetalum, 6 spp.). Pending a complete palynological study of this pollen-morphologically well-characterized group, the fossil types are united here under the Anacolosa type, although some variation in ornamentation of wall is known to exist. The fossil record shows the first occurrence for Australia to be in the Paleocene (HARRlS, 1965). In Borneo the first occurrence is also in the Paleocene (MuLLER, 1968), and the type is regularly present throughout the Tertiary, although a reduction in abundance can be observed in the Mio-Pliocene. In Nigeria the first occurrence is also in the Paleocene, but it is regularly present only UP to the Miocene, after which it becomes very scarce, leading apparently to the present-day rarity of Anacolosa and Ptychopetalum in Africa. In the Caribbean area Anacolosa-type pollen makes its appearance at the Paleocene-Eocene transition and is common only in the Lower and Middle Eocene. In Europe the type has been recorded from the Paleocene and Eocene by ERDTMAN (1954) and KRUSZSCH (1959). From these observations it is clear that as early as Paleocene time the group of olacaceous plants producing the Anacolosa-type pollen (Anacolosa, Cathedra and Ptychopetalum) were widely distributed in Australasia, Africa and Europe, while South America was reached somewhat later. Noteworthy is finally the contraction of area and gradual reduction in abundance during the Neogene. 274
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FABACEAE
(LEGUMINOSAE)--Caesalpinioideae
Caesalpinia type ( Margocolporites vanw(]hei) The earliest record of this highly characteristic pollen type dates from the Middle Eocene in the Caribbean, where it remains present up to Recent. In Nigeria the first appearance is in the Upper Eocene and it is remarkably restricted in its range there, disappearing again in the Lower Miocene. In Borneo it is absent in Cretaceous-Paleocene sediments, but its base is not accurately known. In the Neogene it is fairly common, however. RAMANUJAM (1966) has recorded similar pollen types from the Miocene of south India. Since a number of genera may be represented, it is difficult to be positive about the phyto-geographical significance of these facts. It is possible that Caesalpinia bonduc, which prefers a coastal habitat, has produced a large proportion of the fossil pollen of this type, but in the Caribbean area Caesalpinia coriaria, which is common in the dry thorn forests along the northeastern coast of South America, may also have contributed. Further detailed studies of this group of pollen types will no doubt result in interesting conclusions.
uyACl~AE--Ctenolophoniideae
Ctenolophon The following types can be distinguished: Ctenolophon engleri type (CtenoIophonidites costatus), Ctenolophon type A (Ctenolophonidites lisamae), Ctenolophon parv(folius type (Retistephanocolpites williamsi). The oldest known type at present is the Ctenolophon engleri type, which occurs already in the Senonian of Nigeria, is absent from the Paleocene, but reappears and remains regularly present in younger sediments. The parent plant Ctenolophon engleri is still living in west Africa. A closely similar pollen type, Ctenolophon type A, has a sharply defined base occurrence in the Paleocene of the Caribbean area, but disappears from the record at the Paleocene-Eocene transition. The third pollen type, the Ctenolophon parvifolius type, is first found in Nigeria in the Paleocene, disappearing at the Eocene-Oligocene transition, but present in the Neogene of Borneo, where the parent species C. parvifo#us still lives today. Ctenolophon engleri in Africa and C. parv(folius in the lndo-Malesian area are the only known species of the genus. From these data it is now possible to deduce tentatively the following history for the genus Ctenolophon. Origin probably in Upper Cretaceous time, possibly
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in Africa, followed by an early differentiation into an engleri and parvifolius pollen type, the engleri type remaining present with a short interruption throughout the Tertiary and Quaternary of Africa. Migration of a species with pollen closely related to that of Ctenolophon engleri to South America in the Paleocene, shortly followed by extinction. Migration eastwards of the parv(folius type reaching Malesia probably in the Eocene, becoming extinct in Africa. This history in combination with the peculiar morphology of the pollen grains supports the taxonomical opinion that the genus Ctenolophon is both ancient and sharply differentiated. The pollen types described by A. R. Rao and K. P. Vimal from Indian lignites from Travancore of probably Miocene age and tentatively compared by ERDTMAN (1956) to C. engleri are left out of account here, since descriptions and illustrations are insufficient for proper comparison. MALPIGHIACEAE
Brachypteris type (Perisyncolporites pokornyi) The fossil record for this characteristic pollen type, which occurs in several genera of Malpighiaceae, dates from the Middle Eocene of the Caribbean area. In Nigeria it appears slightly later and remains much more scarce than in the Caribbean area. This is in agreement with present-day distribution of the family, which is best represented in South America, in which continent its origin may have lain. Fruits of Malpighiaceae recorded from the Tertiary of Europe have so far not been accompanied by fossil pollen. The less characteristic pollen of the Malpighiaceae growing in Borneo today, has not yet been found fossil. EUPHORBIACEAE
Alchornea (Psilatricolporites operculatus) The highly characteristic pollen grains of Alchornea are first found in the lower part of the Middle Eocene of the Caribbean area. In Nigeria they appear somewhat later, in the upper part of the Middle Eocene. In Borneo their first origin cannot yet be precisely given. It would appear that the present-day pantropical distribution of the genus was achieved within a comparatively short interval of time in the Eocene.
Amanoa type (Retitricolporites irregularis) This pollen type appears at the base of the Eocene in the Caribbean area and in Nigeria. It is most likely that the genus Amanoa, which occurs both in 276
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South America and in Africa, produced the pollen grains, and this would indicate migration across the Atlantic Ocean in Early Eocene times. BOMBACACEAE
Bombax ceiba type (Bombacacidites annae) The first occurrence of the genus Bombax can be dated as Paleocene in the Carribbean area. No ancestral types are known, however, and the rather sharp lower limit of occurrence suggests immigration from elsewhere. In Nigeria similar, but not identical, pollen types are known from the Paleocene-Eocene transition onwards. In the Caribbean area the Bombax ceiba type becomes rare during the Eocene and has given rise to a host of related types which cannot be discussed here because of their limited stratigraphical interest.
Catostemma (Jandufouria seamrogiformis) The very characteristic Catostemma pollen grains are not found below the Upper Eocene in the Caribbean area. They show strong local dominance especially in the Oligocene and Lower Miocene, which may be taken as an indicator of the presence of rain forest. The origin of this pollen type is not known, but related tricolporate pollen grains referable to the genus Aguiaria occur already in the Lower Eocene. CLUSIACEAE (GUTTIFERAE)
Symphonia globulifera type (Pachydermites diederixi) Symphonia globulifera occurs at present in coastal swamps of tropical Africa and South America and its pollen is highly characteristic. It is the only species of the genus with a relatively wide distribution, the other sixteen species being restricted to Madagascar, where they occur in a variety of habitats. In Nigeria there is clear evidence of first appearance in the Middle Eocene, but in the Caribbean area the first appearance is much later and can be fairly accurately dated as Early Miocene. It would appear reasonable, considering the concentration of endemic and mainly non-coastal species in Madagascar, to assume Africa and probably Madagascar to have been the centre of origin of the genus. At an unspecified time Symphonia globulifera managed to reach the west coast of Africa, arriving in Nigeria at the end of the Eocene and becoming rapidly a dominant species in the coastal vegetation. After a delay corresponding to not more than approx. 25 million years the species succeeded in crossing the Atlantic Ocean and reached the Rev. Palaeobotan.Palynol., 6 (1968) 189-348
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Caribbean area. The means by which this dispersal took place are as yet wholly obscure. At this late stage in the Tertiary the topography must have been similar to present-day conditions, and the chances of Symphonia seeds crossing the Atlantic must have been extremely small. That this nevertheless occurred can hardly be doubted, however, and the long time delay is a silent witness of the numerous unsuccessful attempts which must have preceded the final success. The fact that Symphonia globulifera grows in coastal swamps may have slightly increased its chances of long-distance seaborne dispersal. Similar problems are involved in other transatlantic distribution patterns, but the case of Symphonia has been discussed at length, since here the data are most reliable. LYTHRACEAE
Cuphea (Striasyncolpites zwaardi) The typical pollen grains of the genus Cuphea, which is restricted to America, first appear in the palynological record of the Caribbean area in the Middle Miocene, but no ancestral forms are known.
Crenea ( Verrutricolporites rotundiporis) In the Caribbean area Crenea pollen is first found in the Upper Eocene and is especially common in the Lower Miocene, associated with dominant Rhizophora pollen in coastal sediments. In Nigeria it first appears at the base of the Miocene and is fairly abundant during the Lower Miocene, also in a coastal environment, only to disappear from the stratigraphical record in the Middle Miocene. In the Caribbean area a decrease sets in at approximately the same time, but Crenea pollen remains present in small numbers up to the present day. The palynological data thus provide a fairly complete record of the history of the genus Crenea. Its origin must be sought in the Eocene of South America and it apparently succeeded in crossing the Atlantic Ocean, probably during the Oligocene. It then flourished for a short time on the western African coast in the same environment as in South America. The reasons for its disappearance from Africa and its almost simultaneous decrease in abundance in the Caribbean area are unknown. As in the case of Symphonia, the coastal habitat of Crenea no doubt was a principal factor which significantly increased the chances of dispersal. SONNERATIACEAE
Sonneratia The following types can be distinguished: (l) Ancestral types: (Florschuetzia 278
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trilobata, Florschuetzia semilobata); (2) Sonneratia caseolaris (Florschuetzia levipoli) ; (3) Sonneratia alba (FIorschuetzia meridionalis). The relations between the FIorschuetzia pollen types, which so far only have been found in Borneo, and recent Sonneratiaceae are shown on Fig.16. From this diagram it can be seen that FIorschuetzia trilobata ranges from probably Upper Eocene to Middle Miocene. In its morphology this pollen type shows affinity to certain lythraceous pollen types, notably Lagerstroemia, and it appears not unreasonable to postulate derivation from lythraceous stock during the Eocene. During the Lower Miocene Florschuetzia semilobata enters the stratigraphical record, which type, although transitional specimens are scarce, is assumed to have been derived from F. trilobata by a morphological change from a continuous tectum to a discontinuous one, resulting in a verrucate sculpture, equally distributed over the whole grain, This species has a rather more restricted distribution than F. trilobata and becomes extinct slightly earlier. It cannot be closely matched with the pollen of a living species of Sonneratiaceae or Lythraceae, although there is a certain resemblance with the pollen of Sonneratia gri~thii. Within a relatively short span of time after the appearance of Florschuetzia semilobata, a third related species is noticed, F. levipoli. Between these two pollen types transitions are rather common, with a gradual transition towards a concentration of the verrucate sculpture on the equatorial belt, the formation of tectatepsilate polar caps and the loss of the trilobate condition. Florschuetzia levipoli further shows a statistically significant increase in size during the Mio-Pliocene, and ultimately can be connected with the pollen of the Recent species Sonneratia caseolaris. Slightly later again, in Middle Miocene times, a further differentiation takes place and FIorschuetzia meridionalis makes its appearance, characterized by further modifications in the direction of a meridionally differentiated sculptural pattern, intra-areolate structure on the poles and, compared with F. levipoli, a further increase in size. Transitions with F. levipoli occur in the early part of its range. The youngest fossil specimens of Florschuetzia meridionalis are identical with pollen of the Recent species Sonneratia alba. The changing percentages of the Florschuetzia pollen types are shown on the graph, and are thought to reflect the degree of dominance in the coastal vegetation for each parent species. It would appear from this graph that the ancestral species Florschuetzia trilobata remains present in significant numbers after having given birth to the younger offshoots F. semilobata and F. levipoli. Its disappearance is distinctly gradual. It is not certain whether the parent plant of F. trilobata actually grew in the mangrove environment, but its abundance in Oligo-Miocene coastal sediments of the type in which later Sonneratia and Rhizophora pollen become dominant, strongly suggests this having been the case. The youngest offshoot of the Sonneratia complex proved to be Sonneratia Rev. Palaeobotan. Palynol., 6 (1968) 189-348
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alba, but whether this species originated from S. caseolaris or from the much rarer S. ovata, of which unfortunately no fossil record exists, must remain uncertain for the present. Also the relation to the Indian species S. apetala is unknown for lack of fossil evidence. In this connection it must be stressed that, although it is possible to arrange the pollen types described here in transitional sequence, starting from the simply built FIorschuetzia trilobata and ending with the complex Sonneratia alba pollen, this in itself does not constitute proof of phylogenetic relationship. The fact that this morphological sequence can be shown to have time-stratigraphical significance, the more complex pollen type being the youngest, of course argues for a phylogenetic relationship. However, the rather abrupt change between FIorschuetzia trilobata and F. semilobata is hard to visualize without a sudden change in genetic constitution of part of the F. trilobata population. Or, it may be that this change did not actually take place in northwestern Borneo but elsewhere, and that the newly evolved F. semilobata immigrated soon afterwards. The inferred gradual replacement of the unknown parent plant of the fossil FIorsehuetzia trilobata pollen species by the modern Sonneratia group might reflect ecological competition within the mangrove environment. The development of Sonneratia alba, on the other hand, can be seen as the later origin of a species which is, of all Sonneratia species, best adapted to the marine environment and thus represents a culmination of the evolutionary process. This holds good not only for the ecological adaptation of S. alba, but also for its pollen type, which is the most complex and largest of all Sonneratia pollen types. The large degree of variability in size and morphology observed in the pollen of the living populations of Sonneratia alba, caseolaris and ovata in different parts of their ranges, would indicate that the potentialities for further evolutionary change in pollen characters are by no means exhausted. However, it will be difficult to predict the course of future changes in the absence of any knowledge as to what is precisely the selective value of pollen characters. In particular the size increase in the course of the Neogene observed both in Sonneratia caseolaris and alba pollen deserves special attention in this respect. It has been stated by COVAS and SCHYACK (1945) that pollen size is related to length of style, but in the Sonneratiaceae this relation does not exist, since in the genus Duabanga the style is as long as in Sonneratia, while the pollen grains are much smaller. Nor are the size differences between pollen of Sonneratia alba, caseolaris and ovata correlated with any difference in length of style, which is approximately equal for all three species. With the scarce data available it would appear possible that the increase in pollen size is linked with the gradual physiological adaptation to the saline mangrove environment, since S. alba, which can stand the highest salinities, also has the largest pollen. It is further of interest that pollen fertility in the hybrid S. alba × ovata is higher than in S. alba × caseolaris (MULLER and Hou-L1u, 1966) indicating
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that S. alba is probably more closely related to S. ovata than to S. caseolaris. A further elucidation of these problems will have to be deferred until the discovery, probably in other areas, of fossil Sonneratia ovata, S. griffithii and S. apetala pollen. RHIZOPHORACEAE
Rhizophora type ( Zonocostites ramonae) Included in this type are the pollen grains of the genera Rhizophora, Bruguiera and Ceriops. Although differences in pollen type are known to exist between the genera and constituent species, it has proved impracticable to try to separate them on a routine basis. The following account therefore relates mainly to the history of the tribe Rhizophoreae, to which the genera mentioned belong and which are all mangroves. As far as known the Rhizophora pollen type is unique and cannot be confused with pollen from other taxa (cf. also MULLER, 1964). The fossil record in Borneo shows that the Rhizophora type is absent in Cretaceous and Paleocene sediments. It probably occurs first in Eocene sediments, but due to poor preservation this cannot yet be stated with certainty. In the Oligocene it is definitely present, but in small quantities only; it gradually increases in abundance to become in the Miocene-Pliocene the dominant element in the coastal microflora. In the Caribbean area it is definitely known for the first time in Upper Eocene sediments, being absent in older strata. Again it is only in the Miocene that Rhizophora reaches the high percentages so characteristic of the Neogene and Recent sediments of coastal or marine origin. In Nigeria, in contrast, it is definitely absent from pre-Miocene sediments and starts occurring rather suddenly in high percentages in the lowermost Miocene. If this fossil evidence is combined with the present-day distribution pattern of the tribe Rhizophoreae as discussed recently by VAN SVEENIS (1962a), the following tentative history can be reconstructed: (1) Origin of the tribe Rhizophoreae in the Eocene of southeastern Asia, since today the largest number of genera and species occur there, as well as inland relatives (Carallia, Anisophyllea). (2) Extension of the range of a few species of Rhizophora eastwards across the Pacific Ocean to tropical South America, reaching the Caribbean area via the gap in the Panama isthmus, most probably during the Eocene, followed by development of local species. (3) Crossing of the Atlantic Ocean in the Early Miocene and settling of the American species of Rhizophora on the west coast of Africa. (4) Extension of the range of the Indo-Malesian species of Rhizophora westwards to east Africa at an as yet undetermined time.
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VAN STEENIS (1962a) has concluded that the genus Rhizophora was unable to migrate along the southern tip of South Africa and along the southern shore of the Tethys sea, because of adverse climatic conditions, thus explaining the fact that the east and west African coasts have no Rhizophora species in common. For South Africa this has certainly been the case, but for the Tethys it would appear unlikely. Firstly, the Eocene Period was characterized, as already mentioned in the discussion on Nypa distribution, by an expansion of the tropical belt to higher latitudes and, even at its present location the southern Tethys shore could during this period have been favourable for the growth of Rhizophora. Secondly, it is generally assumed that the formation of the Alps was accompanied by a certain amount of crustal shortening during the considerable compression and overthrusting of the ancient Tethys sediments and therefore the Eocene southern shore could easily have been situated 100-200 km further southwards than its present-day location. It is, therefore, conceivable that the failure of the Indo-Malesian genera and species of Rhizophoreae to reach west Africa is due not so much to a cool climate along the Palaeogene Tethys shores but to the fact that these plants had not fully evolved yet. By the time they had developed the present species and had started to extend their range, i.e., in the Oligo-Miocene Period, the Tethys connection to the Atlantic Ocean had either already closed or was situated too far north in a cooler climatic zone. This alternative hypothesis has of course to be tested by studying the pollen content of the coastal sediments along the ancient Tethys shores. ACANTHACEAE
Justicia type (Multiareolites formosus) Although some of the genera which produce this pollen type have a pantropical distribution, the occurrences in the Neogene appear to be restricted to the Caribbean area and Nigeria. It is possible that the extension of the range to the Indo-Malesian area took place relatively late in the Mio-Pliocene.
Trichanthera type ( Multimarginites vanderhammeni) The genera which produce this pollen type are restricted at present to the American tropics and accordingly the fossil pollen type is known only from the Caribbean area. From the fact that acanthaceous pollen types are only known from the Neogene it might be inferred that this family is of relatively late origin.
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ASTERACEAE (COMPOSITAE) The following three Asteraceae pollen types have been distinguished: (l) Tubul([torae type (Echitricolporites spinosus); (2) Liguliflorae type (Fenestrites spinosus); and (3) Ambrosia type (Echitricolporites mcneillyi). Future detailed studies on well-preserved fossil material will no doubt lead to a further subdivision of these type groups. The Tubuliflorae type appears to be the oldest and the most widespread of the three Asteraceae pollen types. It has not yet been found with certainty in pre-Miocene sediments. In all three areas investigated the very gradual increase in abundance appears to be contemporaneous, but the high percentages reached in the Mio-Pliocene of the Caribbean area have not been found so far in Nigeria or Borneo. The Liguliflorae type is much rarer and has only been regularly observed in the Caribbean area, where it appears slightly later than the Tubuliflorae type. The Ambrosia type, only known from the Caribbean area, appears still later. Asteraceae are widespread in the present-day tropics, but are more common in open vegetation types, such as the savannah or higher montane vegetation than in the closed lowland rain forest. This largely explains the considerable quantities of Asteraceae pollen observed in the Caribbean area Mio-Pliocene in comparison with the relative scarcity in an area such as northwestern Borneo. Earlier views (KUvL et al., 1955) that, on the basis of the palynological record, Asteraceae emerge as one of the youngest developments within the angiosperms are thus confirmed. The place of origin is still obscure, however, and may very well have been situated outside the tropical belt, the time of origin presumably being mid-Tertiary. The relatively quick and simultaneous extension of the range of Asteraceae, especially of the Tubuliflorae type, as shown by the palynological data, probably reflects the efficient seed dispersal which characterizes the family.
SUMMARY OF BOTANICALRESULTS The above examples demonstrate, when an explanation of the stratigraphical distribution patterns is attempted, that a number of problems relating to origin, dispersal and extinction of plant taxa are involved. First of all it must be emphasized, that the data presented give direct evidence only on the development of pollen and spore characters. The first development of a combination of characters similar to that found in the pollen type of a recent taxon does not necessarily mean that all the other characters of flower, fruit and leaves, which define this taxon, also originated at the same time. However, the gradual transformation of a pollen type from an extinct form into one known from a Recent taxon may be taken to
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represent reasonable evidence for time and place of origin. On the other hand a sudden appearance of a new pollen type in the stratigraphical record of one area will in most cases be due to the presence of a stratigraphical hiatus or to immigration. So far only a general dating of first appearance has been possible for some taxa (e.g., Nypa, Ctenolophon, Asteraceae) but ancestral types mostly have not been found, signifying no doubt that the precise place of origin has not yet been sampled. Only in the case of Sonneratia evidence for continuity between an ancestral extinct pollen type and younger, still living offshoots was found. It is expected that future detailed studies of many more, continuous sections will bring to light more examples of this kind. Once the palynological record has registered the origin of a new taxon, it may also provide evidence for its dispersal by recording the extension of range in time and space. The most striking examples of this are represented by those cases where transatlantic migration has to be postulated (Symphonia, Crenea, Amanoa, Rhizophora, Malpighiaceae). The significance of these data can of course only be evaluated if reasonable estimates of dispersal probabilities and reliable palaeogeographic information are available. As regards the first point, transatlantic dispersal of the taxa involved under present-day conditions appears virtually impossible. Also geological evidence is not in favour of closer geographic connections between tropical Africa and South America in the Tertiary. It would, therefore, appear justified to regard the cases cited as indeed reflecting rare instances of long-distance dispersal of diaspores, illustrating SIMeSON'S (1952) opinion that, given enough time even the most unlikely events will occur. Nevertheless, at the same time, it must be stressed that a general exchange of floral elements between Africa and South America is definitely not visible in the Tertiary palynological record. The undoubted floristic affinities between these two areas, referred to by plant geographers from ENGLER (1905) onwards must date, therefore, from earlier periods. The palynological record also shows many examples of contraction of range, leading in extreme cases to extinction. It is generally impossible to pinpoint the causes, although in a general way climatological changes, which can be deduced from large-scale changes in the palynological record, must play an important part. Other contributory factors, which may well be responsible, are competition due to immigration or the evolution of new floral elements.
PLATE I 1. Foveotriletes margaritae (VAN DER HAMMEN) nov. comb., Colombia. 2. Foveotriletes margaritae (VAN DER HAMMEN) nov. comb., Venezuela. 3. Crassoretitriletes vanraadshooveni nov. gen., nov. sp., Nigeria, holotype. Magnification × 1,000.
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PLATE[
i
i i ¸I¸¸¸ii •
I
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SYSTEMATICALPART
Division I Sporites H. POTONIL 1893
Class A Triletes (REINSCH, 1881) POTONIE et KREMP, 1954 Genus Foveotriletes (VAN DER HAMMEN, 1954) ex R. POTONII~, 1956
Foveotriletes margaritae (VAN DER HAMMEN, 1954) nov. comb. (Plate I, 1, 2) Literature: Triletes margaritae VAN DER H AMMEN, 1954, p.102, pl.17. Remarks: The original short diagnosis is here enlarged. The identity of the specimens described by us has been confirmed by Van der Hammen. Description." Single grain, radially symmetrical, anisopolar with rounded distal pole and slightly pointed proximal pole, in polar view subangular; shape spherical-suboblate. Laesura trilete, relatively short (7-13/~), straight, sometimes inconspicuous. Foveolate; foveolae circular-oval, ~-2/~ wide, 1-2 ~t apart, exine 1-2 ~ thick. Dimensions: 44-56 # (equatorial diameter). Variability: In size and coarseness of sculpture. Comments: This species differs from Filtrotriletes nigeriensis VAN HOEKENKLINKENBERG, 1966 in its thinner wall and shorter, less pronounced laesura. Distribution: Lower part of the Proxapertites operculatus Zone in Nigeria and northern South America, decreasing in frequency in the upper part of the Retidiporites magdalenensis Zone. Extinct in younger zones. Taxonomic affinities: Unknown, although some similarity exists with published illustrations of Lindsaya orbiculata, Ophioglossum falcatum, O. concinnuum, and Botrychium subbiJbliatum, none of which was available for comparison. Genus Crassoretitriletes nov. gen.
Derivatio nominis: Name derived from the coarsely reticulate ornamentation. Diagnosis: Spherical, trilete, entirely coarsely reticulate with undulating muff; thick-walled, laesura indistinct. Type species: Crassoretitriletes vanraadshooveni nov. sp. The type material of the new species described below has been deposited at the Palynological Section, Botany Department, Municipal University, Amsterdam (The Netherlands). 286
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
Crassoretitriletes vanraadshooveni nov. sp. (Plate I, 3; holotype) Derivatio nominis: Named in honour of Mr. B. van Raadshooven in recognition of his contribution to Venezuelan palynology. Holotype: Slide No. TC-151, well Egbema-l, 3015 ft., Nigeria. Description: Single grain, radially symmetrical, anisopolar, with rounded distal pole and slightly pointed proximal pole, in polar view almost circular. Laesura trilete, indistinct, often covered by sculpture. Reticulate over entire surface; muri undulating, 3-4/z wide, 2/z high, lumina 2-4/z wide, 6-12 /z long. Exine 14-2 # thick. Dimensions: 58-101 /~ (equatorial diameter). Variability: Moderately variable in size and in coarseness of sculpture. In Borneo a distinct variety has been observed in which the wall is finely perforated, but this is included in the species. Distribution: Pantropical approximately from the base of the Crassoretitri/etes vanraadshooveni Zone upwards, but disappearing in northern South America at the base of the Echitricolporites spinosus Zone. First appearance in Borneo slightly earlier than in the Caribbean area, in Nigeria even at the base of the Verrutricolporites rotundiporis Zone. Taxonomic affinities." Close correspondence virtually amounting to identity exists with Lygodium microphyllum (Plate II, 1) (~- Lygodium scandens). This is based on Recent material collected in Nigeria and Borneo. However, NAYARet al. (1964) have recently described the spore of Lygodium microphyllum as tuberculate distally and smooth proximally. Evidently a different species is involved and checking of the original herbarium sheets is necessary to resolve this discrepancy. Genus Cicatricosisporites POTON~ et GELLZTJCH, 1933
Cicatricosisporites dorogensis POTONII~et GELLETICH,1933 (Plate I1, 2) Literature: Cicatricosisporites dorogensis POTONI~et GEt LETICH, 1933, p.522, pl. 1, fig. 1-5. Striatriletes susannae VAN DZR HAMMEN, 1956d, p.l 15, fig.5. Description: Single grain, radially symmetrical, anisopolar, with rounded distal pole and pointed proximal pole; in polar view semi-angular to almost circular. Laesura trilete, short. Contact area of proximal face unsculptured, remainder of wall striate or striate-rugulate. Striae 1~-2 # high, ~--1/z wide; grooves between striae lz-2~/~ t l wide. Exine 1½-2/~ thick. Dimensions: 55-70 ~u (equatorial diameter). Variability: Moderately variable in size and ornamentation. Compared to Rev. Palaeobotan. Palynol., 6 (1968) 189-348
287
Cretaceous representatives of this species the variability is much less in our Tertiary material and the spores are certainly identical with the type as originally described by POTONI~ and GELLEVlCH(1933), and later on from the same locality by KDVES (1960, 1961). Distribution: In northern South America ranging from the base of the Verrucatosporites usmensis Zone to the lower part of the Magnastriatites howardi Zone (top Cicatricosisporites dorogensis Zone), higher occurring sporadically~ possibly reworked. In Nigeria ranging from slightly above the base of the Verrucatosporites usmensis Zone to approximately the same level in the Magnastriatites howardi Zone (top Cicatricosisporites dorogensis Zone). In Borneo virtually absent during the whole of the Tertiary. Taxonomic affinities: Similar spores are found in the genera Anemia and Mohria (Schizaeaceae). Genus Magnastriatites nov. gen.
Derivatio nominis: Name derived from the coarsely striate ornamentation. Diagnosis." Spherical, trilete, coarsely striate, except on the proximal contact area which is surrounded by a circular ridge. Striae continuous, grooves about as wide as ridges, size around 100 ~t. Type species: Magnastriatites howardi nov. sp. Comments." The genus differs from Cicatricosisporites in the relatively smaller number of coarser striae, the circular ridge surrounding the smooth proximal contact area and the much larger size. Magnastriatites howardi nov. sp. (Plate IIl, 1; holotype)
Derivatio nominis: Named in honour of Mr. E. A. Howard in recognition of his contribution to Trinidadian palynology. Holotype: Slide No. TC-152, well Dificil-1, 1300-1308 ft., Colombia. Description: Single grain, radially symmetrical, anisopolar, with rounded distal pole and more pointed proximal pole, in polar view nearly circular; shape suboblate-spherical. Laesura trilete, costate; costae 2 # wide. Contact area of
PLATE II 1. Lygodium microphyllum R. BROWN, Recent. 2. Cicatricosisporites dorogensis POTONII~ et GELL~TJCH, Nigeria. 3. Verrucatospor#es usmensis (VAn DER HAMMEN) nov. comb., Nigeria. 4. Stenoehlaena palustris BEDDOME, Recent. Magnification × 1,000. 288
Rev. Palaeobotan. Palynol., 6 (1968) 189 348
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proximal face psilate, surrounded by a circular ridge, which makes contact with the striate ridge pattern at the points of the laesura. Remainder of wall coarsely striate; striae 1-2/~ high, 2-3½/z wide; grooves 1~-3 ~t wide. Exine 1~-2~ ~ it thick. Dimensions." 77 132/z (equatorial diameter). Variability: There is some variability in size and sculpture; thicker striae may occur in smaller number or much wider grooves. Also the proximal side of the grain may be locally perforated. Distribution: Regularly present from the base of the Magnastriatites howardi Zone upwards, in all three areas. Its first appearance is remarkably sudden and, as far as can be judged simultaneous. No ancestral forms are known. Taxonomic affinities." Virtually identical with the spores of the tropicalsubtropical fresh-water fern genus Ceratopteris (species seen: C. thalictroides, Plate IV, 1, and C. cornuta).
Class B Monoletes IBRAHIM, 1933 Genus Verrucatosporites (PFLuG, 1952)ex R. POTONI~, 1956 Comments: The spores described by VAN DER HAMMEN (1956d) under the genus Verrumonoletes clearly fall within the circumscription of Verrucatosporites and this name has priority. Verrucatosporites usmensis (VAN DER HAMMEN, 1956d) nov. comb. (Plate II, 3) Literature: Verrumonoletes usmensis VAN DER HAMMEN, 1956d, p.116, fig.7. Remarks: The paper cited above consists of a Spanish (VAN DER HA~MEN, 1956C) and translated English text (VAN DER HAMMEN, 1956d). In the former the species name is given as "usmensoides", in the latter as "usmensis". In agreement with Van der H a m m e n the name "usmensis" is taken as the correct one, referring also to Plate I, 7. Description: Single grain, bilaterally symmetrical, anisopolar, with convex distal outline and straight or slightly concave proximal outline; in polar view ellipsoidal. Laesura monolete. Geminate; gemmae 12-2~ ~ ~ # high and 17-2z ~ /z wide at base, rather widely and variably spaced. Exine thickness I ,u. P L A T E III 1. Magnastriatites howardi nov. gen., nov. sp., Colombia, holotype. 2. Grimsdalea magnaclavata nov. gen., nov. sp, Trinidad, holotype. 3. Monoporites annulatus VAN DER HAMMEN,Venezuela. Magnification × 1,000. 290
Rev. Palaeobotan. Palynol., 6 (1968) /89 348
>
Dimensions: 39-61 /t, including gemmae. Variability: In size and coarseness of sculpture. Comments: The species most probably has evolved from a verrucate ancestral type, since transitions are common at the base of its range in Venezuela. Distribution: First regular occurrence marks the base of the Verrucatosporites usmensis Zone. In northern South America the species then remains present throughout the Tertiary, but in Nigeria a sharp decline occurs at the base of the Verrutricolporites rotundiporis Zone. In Borneo the species remains very common up to the Recent. Taxonomic affinities." Although a verrucate sculpture is very common among fern spores of varied taxonomic affinities, a geminate sculpture in which the gemmae are separated from each other is much rarer and has so far only been found in Stenochlaena palustris, an Indo-Malesian climbing fern (Plate I1, 4). It is, however, possible that other members of this genus show the same pollen type, since only a restricted number of species was available for comparison. Spores which show a transition between verrucate and geminate are produced by Phlebodium aureum and Histiopteris incisa.
Division II Pollenites R. POTONII~, 1931
Class lnaperturatae IVERSEN et TROELS SMITH, 1950 Genus Grimsdalea nov. gen.
Derivatio nominis." The genus has been named in memory of the late Dr. T. F. Grimsdale, who launched the idea of applying palynology in oil exploration in 1937. Type species." Grimsdalea magnaclavata nov. sp. Diagnosis: Spherical, aperture indistinct or absent, wall thin, intectate, sculpture of two types, finely scabrate and coarsely clavate. Grimsdalea magnaclavata nov. sp. (Plate II1, 2; holotype)
PLATE IV
1. Ceratopteris thalictroides BRONGNIART,Recent. 2. Spinizonocolpitesbaculatus MULLER,Venezuela. 3. Spinizonocolpitesechinatus MULLER,Venezuela. Magnification × 1,000. 292
Rev. Palaeobotan. Palynol., 6 (1968) 189 348
PLATE IV
2 Rev. Palaeobotan. Palynol., 6 (1968) 189-348
293
Derivatio nominis: Name derived from the clavate ornamentation. Holotype: Slide No. TC-153, well Fe-100, 2365 ft., Trinidad. Description: Single grain, possibly bilaterally symmetrical, isopolar, almost spherical. Aperture absent or indistinct. Wall intectate, densely covered with a finely baculate-scabrate sculpture as well as with scattered large clavae. Clavae 8-10 # apart, 7-10 # long, 22!-3/~ thick, sunken into locally thickened endexine with a conical base. Endexine 1 #, but underneath clavae 2-2½ /~ thick. Columellae ½ # thick and long. Dimensions: 40-62 # (excluding of clavae). Variability." Some variability in size and wall thickness occurs. Distribution." Restricted to the Caribbean area where it occurs from the base of the Grimsdalea magnaclavata Zone upwards to the lower part of the Alnipollenites verus Zone, where it apparently becomes extinct. Taxonomic affinities: Unknown, possibly derived from an extinct palm species. Class Monoporatae IVERSENet TROELSSMI]'H, 1950 Genus Monoporites (CooKSON, 1947) ex VAN DER HAMMEN, 1954
Monoporites annulatus VAN DER HAMMEN, 1954 (Plate III, 3) Literature." Monoporites annulatus VAN DER HAMMEN, 1954, p.90, pl.6, fig.4. Monoporites unipertusus VAN DER HAMMEN, 1956b, p.82, pl.5, fig.10.
Description." Single grain, radially symmetrical, anisopolar, almost spherical. Single aperture small, circular, penetrating entire wall, costate; costa 4~-/~ wide, slightly protruding. Endexine < ¼/~ thick; columellae indistinct <: ¼/~ long and thick; tectum < ¼ # thick, psilate-very finely perforate or scabrate. Dimensions." 38-43/~. Variability: Considerable variability in size of grain and pore exists, but the wall is always rather thin. The surface of the wall is mostly smooth but a finely scabrate surface occurs occasionally. Since it is mostly unknown whether this condition is due to corrosion or not, this sculpture type is included. Distribution: In the Caribbean area and in Nigeria occurring regularly from the base of the Monoporites annulatus Zone upwards, although with rather pronounced fluctuations in numbers and generally more abundant in the Neogene than in the Palaeogene. Rare occurrences below the base of the Monoporites annulatus Zone are known. In Borneo base not yet determined, but absent in Paleocene and Upper Cretaceous. The significance of the fluctuations of grass pollen has been discussed in the section "Botanical results". 294
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
Taxonomic affinities: The fossil species closely resembles non-cultivated Poaceae (Gramineae) pollen. Since the type is produced by many different genera, further identification is not possible at present.
Class Monocolpatae IVERSEN et TROELS SMITtt, 1950 Genus Spinizonocolpites MULLER, 1968
Spinizonocolpites echinatus group (Plate IV, 2, 3)
Literature: Spinizonocolpites echinatus MULLER, 1968. Spinizonocolpites baculatus MULLER, 1968. Remarks: The distinction made by Muller between an echinate and a baculate form was not made in all areas and consequently for the present review the two species have to be grouped together. Description: Single grain, radially symmetrical, slightly anisopolar, since the grains are separated by a continuous equatorial colpus into two slightly unequal parts; suboblate-spherical. Colpus ectexinous, somewhat irregularly bordered, with a narrow indistinct margin of thinning ectexine. Total wall thickness about 1½/~; endexine ½ # thick, columellae < 1 /~ long, < ½/~ thick, covered by a thin, finely reticulate tectum; lumina < 1 /~, muri ½ # wide and thick. Spines scattered on tectum, 5-13 # long, 10-12/~ apart, either echinate, conical with a rather blunt to pointed apex and with the lower part often slightly expanded (Sp. echinatus) or baculate with rounded or slightly pointed tips, straight or slightly curved (Sp.
baculatus). Dimensions: 30-62/~. Variability: The two species grouped here together are in general rather distinct, but transitional specimens do occur occasionally. In both there is some variability in thickness of wall and coarseness of reticulation. Distribution: Occurs throughout Upper Cretaceous and Palaeogene of all three areas, but disappears from the record in the Caribbean area approximately in the higher part of the Verrucatosporites usmensis Zone. In Nigeria the species disappears slightly higher since it occurs in the whole of the Verrucatosporites usmensis Zone. In Borneo present up to the Recent. In Upper Cretaceous-Paleocene sediments of all three areas, Sp. baculatus is the dominant form, while later Sp. echinatus is found exclusively. This distribution together with the occurrence of transitional forms suggest a phylogenetic connection. Taxonomic affinities: The echinate form is identical with pollen of Nypa fruticans (Arecaceae or Palmae, Plate V, 1) and cannot be confused with any other pollen type known at present. The baculate form is not matched yet, and probably
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
295
represents an extinct ancestral form. Nypafruticans is at present restricted to the mangrove environment of the humid Indo-Malesian tropics, from the Ganges delta to northern Australia. Genus Proxapertites VAN DER HAMMEN, 1956c
Proxapertites operculatus (VAN DER
HAMMEN,
1956c)
(Plate V, 2)
Literature: Monocolpites operculatus VAN DER HAMMEN, 1954, p.89, pl.5, fig.2-3.
Proxapertites operculatus VAN
DER HAMMEN, 1956c, p.105, pl.l,
fig.3.
Description." Single grain, radially symmetrical, slightly anisopola~', since the grains ,-,re separated by a continuous equatorial colpus into two slightly unequal parts; oblate, in polar view rounded angular to oval; colpus ectexinous, somewhat irregularly bordered by a narrow, indistinct margin of thinning ectexine. Total wall thickness 1-2/z; endexine < 1 /z thick; columellae indistinct, -: I ,u long, ~ ½ # thick, covered by a <: 1 /z thick finely reticulate-perforate tectum; lumina 1 # wide, smaller along margin of colpus, muri ½ it wide, < 1 ,u high. Dimensions: 35-61 kt. Variability." In size and shape. Comments: The grains are here described as monads, while Van der Hammen suggests that they are dyads with the apertural faces touching. For a full discussion of this question see MULLER (1968). The species differs from the closely related Proxapertites cursus by its finer sculptural pattern, its generally isodiametrical lumina and the finer columellae which are more circular in cross-section. Distribution: Regularly present in the Proxapertites operculatus Zone in all three areas, but apparently appearing in Nigeria later than in the Caribbean area. In the younger zones the distribution is also different. In the Caribbean area decreasing in number in the Monoporites anmdatus Zone, but irregularly present also in much younger zones. In Nigeria its greatest abundance appears to fall in
PLATE V 1. 2. 3. 4. 5. 6. 7.
Nypa fruticans THUNBERG, Recent. Proxapertites operculatus (VAN DER HAMMEN), Colombia. Proxapertites cursus VAN HOEKEN-KLINKENBER6, Nigeria. Longaoertites vaneendenburgi nov. sp., Venezuela, holotype. Psiladiporites minimus VAN DER HAMMENet WYMSTRA,Trinidad. Sorocea ilicifolia MIQUEL, Recent. Retidiporites rnagdalenensis VAN DER HAMMENet GARCIA, Venezuela.
Magnification × 1,000.
296
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
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the Monoporites annulatus Zone; it is thereafter irregularly present, except in the youngest zones. In Borneo only known from the Proxapertites opereulatus Zone and probably disappearing from the stratigraphical record earlier than in the other two areas. Taxonomic affinities: In our opinion not derived from Astroca~3,um as suggested by VAN DER HAMMEN (1956C), but from an extinct group of palms related to Nypa (ref. MULLER, 1968).
Proxapertites cursus VAN HOEKEN-KLINKENBERG, 1966 (Plate V, 3)
Literature: Proxapertites cursus VAN HOEKEN-KLINKENBERG, 1966, p.43, pl.Ill, fig.2.
Description: Single grain, radially symmetrical, slightly anisopolar, since the grains are separated by a continuous equatorial colpus into two, slightly unequal parts; oblate, in polar view oval; colpus ectexinous, somewhat irregularly bordered by narrow, indistinct margins of thinning ectexine. Total wall thickness 2-4 /~; endexine 1 # thick; columellae rather distinct, straight, 1-2 ~ long, round to oval in cross-section, 1 /~ thick, covered by a l kt thick reticulate tectum; muri flat to rounded, 1-1½ /~ wide, 1 /t high, lumina up to 2 ,u in diameter, variable in size and shape, generally elongated oval or curved. Dimensions: 35-69/~. Variability: Rather variable in coarseness of wall structure, but attempts to split the type into smaller units according to the coarseness of the reticulum have been fruitless. Comments: As with the preceding species, in disagreement with its author, the grains are here described as monads. Differs from Proxapertites operculatus mainly in coarser reticulum with oval muri and distinct columellae. Distribution: Regularly occurring in the upper part of the Proxapertites operculatus Zone of all three areas, but base and top are strikingly different. In the Caribbean area starting at the base of the Ctenolophonidites lisamae Zone and disappearing from the record in the uppermost part of the Retibrevitricolpites triangulatus Zone. In Nigeria the first occurrences are in the lowermost part of this zone and the species is ranging upwards into the uppermost part of the Verrucatosporites usmensis Zone. In Borneo base and top occurrences are not exactly known yet, but the species is absent in younger zones. Taxonomic affinities: Clearly related to Proxapertites opereulatus and, therefore, affinities with Nypa also likely. Genus Longapertites VAN HOEKEN-KLINKENBERG, 1964
Longapertites vaneendenburgi nov. sp. (Plate V, 4; holotype) 298
Rev. Palaeobotan. Palynol., 6 (I 968) [ 89-348
Derivatio nominis: Named in honour of Mr. D. van Eendenburg in recognition of his contribution to Bornean and Trinidadian palynology. Holotype: Slide TC-154, well VLE-415, 13998-14037 ft., Venezuela. Description: Single grains, bilaterally symmetrical, anisopolar, the distal side arched and provided with a long colpus, the proximal side flat or slightly convex; in polar and in equatorial view oval. Colpus ectexinous, wide, slightly intruding, extending over about 2/3 of the greatest circumference of the grain. Wall thin, < 1 #; columellae only visible in central part near colpus, almost ½/z long, ¼ ~ thick; tectum evenly and finely perforate; muri ~/z, lumina ½ # in width. Dimensions: 59-83 ,u. Variability: Rather uniform in appearance. Comments: The species differs from Longapertites marginatus VAN HOEKENKLINKENBERG in the absence of a coarser reticulate pattern on the proximal side, and from Longapertites proxapertioides VAN DER HAMMENet GARCIA in the finely perforate wall, with lumen size <~ 1 /z. Distribution: In the Caribbean area restricted to the Foveotrico/pites margaritae and the Retidiporites magdalenensis Zone, but in Nigeria already present in the Proteacidites dehaani Zone and disappearing in the lower part of the Retidiporites magdalenensis Zone. Taxonomic affinities: The grain is probably derived from a palm species, but no distinct affinities can be listed. The wall structure of Pritchardia kamapuaana is rather similar, but the colpus is much shorter here. An arched colpus of the Longapertites type on the other hand is found in the genus Eugeissona, but here the wall structure is different.
Class Diporatae |VERSEN et TROELS SMITH, 1950 Genus Psiladiporites VARMA et RAWAT, 1963
Psiladiporites minimus VAN DER HAMMEN et WVMSTRA, 1964 (Plate V, 5)
Literature: Psiladiporites minimus VAN DER HAMMEN et WYMSTRA,1964, p.233, pl.I, fig.10.
Description: Single grain, radially symmetrical, isopolar, oval in equatorial and polar outline; diporate, pores penetrating both ectexine and endexine, 3-5 # wide, simple. Wall -~-/zthick, without distinct layers, psilate or very finely perforate. Dimensions: 13-21 #. Variability: Mainly in size and width of pores. Distribution: In the Caribbean area not found below the Verrutricolporites rotundiporis Zone with a distinct concentration in the Psiladiporites minimus Zone. Rev. Palaeobotan. Palynol., 6 (1968) 189-348
299
In Nigeria not observed, in Borneo mainly concentrated in the Eehitricolporites spinosus Zone. Taxonomic affinities: The genera Artocarpus, Ficus, and Sorocea (Plate V, 6, Moraceae) have very similar pollen and the fossil species is likely to have been derived from several genera of Moraceae, but there is little likelihood of further identification, since the differences between the genera in this family are small. Genus Retidiporites VARMA et RAWAT, 1963
Retidiporites magdalenensis VAN DER HAMMEN et GARCIA, 1966 (Plate V, 7) Literature: Retidiporites magdalenensis VAN OER HAMMEN et GARCIA, 1966, p. 109, fig.9. Description: Single grain, radially symmetrical, isopolar, oval in equatorial and polar outline; diporate, pores penetrating both ectexine and endexine, circular, 6-13/z wide, simple. Endexine 1- < ½ # thick; columellae ½-~i ½/~ long, < ½ ,u thick; tectum ½ - < ½ # thick, evenly reticulate-perforate, occasionally slightly finer near pores; lumina < -~-2/t wide, muri - ~-1½ ~t wide. Dimensions." 24-51 /z. Variability: Larger grains generally show a coarser ornamentation. Comments." Retidiporites bengalensis described by VARMA and RAWAT (1963) shows some similarity, but differs in possessing an endexine twice as thick as the ectexine. Distribution: Both in the Caribbean area and Nigeria regularly occurring in the Proxapertites operculatus Zone, but in the former area extending some distance in the Monoporites annulatus Zone, in the latter disappearing at the top of the Retidiporites magdalenensis Zone. Unknown from Borneo. Taxonomic affinities: Obscure, although some superficial resemblance exists with Banksia collina and Dryandra hmgifolia (Proteaceae).
PLATE VI
1. Multiareolitesformosus (VAN DER HAMMEN)nov, comb., Venezuela, upper focus. 2. Multiareolitesformosus (VAN DER HAMMEN)nov. comb., Venezuela, lower focus. 3. Dianthera americana LINNAEUS, upper focus, Recent. 4. Dianthera americana LINNAEUS, lower focus, Recent. 5. Multimarginites vanderhammeni nov. sp., Venezuela, holotype, upper focus. 6. Multimarginites vanderhammeni nov. sp., Venezuela, holotype, lower focus. 7. Trichantheragigantea HUMBOLDTet BONPLAND,upper focus, Recent. Magnification × 1,000. 300
Rev. Palaeobotan. Palynol., 6 (1968) 189 348
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Class Dicolporatae new class
Diagnosis: Pollen grains with two ectexinous colpi combined with two endexinous pores. Genus Multiareolites nov. gen.
Derivatio nominis: Name derived from circular areas of thickened ectexine. Diagnosis: Prolate, in polar view oval, dicolporate, colpi ectexinous, meridional, intersubangular, pores endexinous. Ectexine thickened on intercolpate areas and in rows of circular areas, 2-4/~ in diameter, bordering the colpi, columellae coarser in thickened areas. Type species." Multiareolites formosus ex VAN DER HAMMEN, 1956b. Comments: Van der Hammen has described the species Dicolporites Jormosus nov. gen. nov. sp. with a pollen grain derived from a Recent plant as type. Because this procedure is invalid according to the International Code of Botanical Nomenclature and because he has not since described a fossil grain of this type, the opportunity is taken to create a new genus for this pollen type, in order to do justice to its peculiar morphology. As genotype the fossil representative of Van der Hammen's original species is chosen and its name adopted. The genus name Dicolporites has been elevated in taxonomic rank and used to name the class Dicolporatae. Multiareolitesformosus (VAN DER HAMMEN, 1956b) nov. comb. (Plate VI, 1, 2) Literature: Dicolporites formosus VAN DER HAMMEN, 1956b, p.85, pl.6, fig.16.
Description: Single grain, radially symmetrical, isopolar, prolate, in polar view oval with colpi intersubangular. Dicolporate, colpi ectexinous, narrow with straight borders and pointed ends, pori indistinct, probably endexinous. Endexine < ½/~ thick, ectexine thickened on intercolpate areas and in single or double rows of circular "areoli", 2-4 # in diameter; columellae straight, sometimes slightly branched, longer and much coarser in areas where endexine is thickened, 2 ,u long on intercolpate areas and areoli, shorter on poles and along colpi, slightly irregular in outline and up to 1/~ thick on intercolpate areas, fine and probably isodiametric on rest of grain. Tectum ½ # thick, smooth or finely verrucate due to protruding columellae, probably finely perforate. Dimensions: 28-38/~. Variability: Smaller grains show a single row of areoli, while larger ones generally bear double rows. There is in addition variation in the distribution of areas with longer and coarser columellae and in the presence or absence of distinct 302
Rev. Palaeobotan. PalynoL, 6 (1968) 189-348
pores. The material did not permit a further separation and in the counting of samples all these variations have been grouped under the variable species Multiareolites formosus. Distribution: In the Caribbean area and Nigeria restricted to the Echitricolporites spinosus Zone. Not observed in Borneo. Taxonomic affinities: This very characteristic pollen type has only been observed in the following genera of the Acanthaceae: Adhatoda, Anisotus, Beloperone, Dianthera, Jacobinia, Justicia, Kolobochilus, Monechma, and Rungia. Justicia americana and Dianthera americana (Plate VI, 3, 4) come very close to the fossil grains, but it is of course not possible to be sure just which genera or species are represented. Genus Multimarginatus nov. gen.
Diagnosis: Spherical, di- or tricolporate; colpi long, multimarginate, in dicolporate grains crossing perpendicular (90 ° rotated bilaterally symmetrical), in tricolporate grains colpi always normally orientated; wall thick, tectum perforate or foveolate-fossulate. Type species: Multimarginites vanderhammeni nov. sp. Multimarginites vanderhammeni nov. sp. (Plate VI, 5, 6; holotype) Derivatio nominis: Named in honour of Dr. Th. van der Hammen in recognition of his contributions to South American palynology. Holotype: Slide TC-155, well Hervidero-l, 2770 ft., Venezuela. Description: Single grain, 90 ° rotated bilaterally symmetrical, isopolar, spherical; dicolporate; colpi very long, ectexinous, bordered by 3-4 strips, 4-5/z wide, perpendicularly orientated, straight borders and pointed or rounded ends; pori endexinous, transversely elongated, 4/z wide, 13 # long, constricted in the middle, costate; costae strongly protruding, 1½-2/~ thick. Endexine < 1 /z thick; columellae 1 # long, ½/z thick, tectum 2/z thick, foveolate, lumina I~-2 # wide, muri 2-3/z thick. Dimensions: 40-53/~. Variability: In size and coarseness of sculpture. Distribution: Only known from the Caribbean area where it occurs from the base of the Retitriletes vanraadshooveni Zone upwards. Taxonomic affinities: Close resemblance exists with Sanchezia klugii and Trichanthera gigantea (Plate VI, 7; Plate VII, 1). The latter grain, however, has a considerably larger size (105 #!). Other multimarginate species of Acanthaceae available are non-rotated symmetrical (Asteracantha longiJblia, Asystasia vogeliana, M imulopsis solmsii). Rev. Palaeobotan.Palynol., 6 (1968) 189-348
303
Class Triporatae IVERSENet TROELS SMITH, 1950 Genus Florschuetzia nov. gen. Derivatio nominis: The genus has been named in memory of the late Prof. Dr. F. Florschfitz, the founder of palynology in The Netherlands. Diagnosis: Subprolate, sometimes trilobate and with meridional ridges. Pores equatorial, circular, distinct. Wall tectate, columellae generally indistinct, sometimes fused. Tectum continuous, smooth or broken up into separate verrucae and differentiated in polar and/or meridional direction. Type species: F/orschuetzia tri/obata nov. sp. Comments: The genus differs from Verrutrico/porites VAN DER HAMMEN in the absence of colpi, the indistinctly columellate structure and the absence of a supratectate verrucate sculpture. The diagnosis has been taken wide enough to include the fossil sonneratioid pollen types, including the presumed ancestral one. Some confusion may, however, be possible with a "sporotype" described in 1954 by COOKSON and PIKE and named Santa/umidites, the description of which has subsequently been emended and accepted as a valid form genus by POTONI~(1960). In both Cookson and Pike's and Potoni6's diagnosis it is clearly stated that the maximum thickness of the wall is around the pores, as is the case in Santa/urn pollen. No confusion with Florschuetzia appears likely, therefore, and the genus would not have to be mentioned here, but for the fact noted before (MULLER, 1964) that the photomicrographs accompanying Cookson and Pike's paper strongly suggest that fossil pollen of Sonneratia caseo/aris has been included in S a n t a & m # dites (see especially their fig. 71, pl. 2, which is strikingly similar to F/orschuetzia levipoli). This suspicion is strengthened by Cookson and Pike's discussion of the affinities of Santalumidites cainozoicus in which the authors mention puzzling differences with recent Santalum pollen and a large degree of variability as well. If this would indeed prove to be the case, there would have been no choice left, other than correcting Cookson and Pike's description of the type and accepting
P L A T E VII 1. Trichanthera gigantea HUMBOLDTet BONPLAND,lower focus, Recent. 2. Florschuetzia trilobata nov. gen., nov. sp., Borneo, holotype. 3. Florschuetzia trilobata nov. gen., nov. sp., Borneo. 4. Florschuetzia trilobata nov. gen., nov. sp., Borneo. 5. Lagerstroemia speciosa (LINNAEUS)PERSOON,Recent. 6. Florschuetzia semilobata nov. gen., nov. sp., Borneo. holotype. 7. Florschuetzia semilobata nov. gen., nov, sp., Borneo. 8. Florschuetzia semilobata nov. gen., nov. sp., Borneo. 9. Florschuetzia levipoli nov. gen., nov. sp., Borneo. Magnification × 1,000.
304
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'i~i~
~!,i~i! ~i~,!i!~,i',i~,i,~i!~.,'~ ~
ii~i!!i~!Ui~ ¸¸
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that Santalumidites had priority above Florschuetzia. However, since no type specimen has been preserved, nor type locality been designated by Cookson and Pike, it is impossible to verify this assumption. The photomicrographs alone, on which no structural details can be observed are considered inadequate also for selection of a lectogenotype, the more so since some of the diagnostic characters of the genus are not visible on the pictures. In view of this it was decided to follow recommendation PB 6 F (p.56) of the International Code of Botanical Nomenclature, which advises not to apply names originally attached to inadequately described or figured specimens to well preserved material. Hence the new genus Florschuetzia is established.
Florschuetzia trilobata nov. sp. (Plate VII, 2; holotype; Plate VII, 3, 4) Derivatio nominis: Name derived from the trilobate shape. Holotype: Slide TC-156, surface sample Dz-4493, northwestern Borneo. Description: Single grain, radially symmetrical, isopolar; prolate; in polar view strongly lobate. Triporate, pores circular, 2-4/z in diameter, intersubangular, ectexinous + endexinous; rarely, pores are combined with ~: colpoid grooves, which may be flanked by relatively short secondary meridional thickenings. Total wall thickness 2-3 /z on poles and meridional ridges, ± 1 /z on porate fields; endexine 4- ½/t thick; columellae generally indistinct, ½-1/~ long; tectum psilate, not clearly differentiated from underlying columellae, 1-2 ,u thick on poles and meridional ridges, probably < 1 /z on porate fields. Dimensions: 28-35 ,u. Variability: In degree of wall thickening on meridional ridges and in the occasional presence of colpoid grooves with secondary meridional ridges. Distribution: Only known from Borneo, earliest occurrence in Oligocene sediments (probably Verrucatosporites usmensis Zone), very abundant in the Magnastriatites howardi and the Crassoretitriletes vanraadshooveni Zone, disappearing from the record early in the Echitriporites spinosus Zone. Remarks: The species is distinguished from the psilate variations of Verrutricolporites rotundiporis by its larger size, trilobate condition, thickened meridional ridges and the nearly massive wall in which generally only a faint columellate layer is visible. The species differs from Florschuetzia semilobata in the psilate wall and the often pronounced meridional ridges. Taxonomic affinities: In general shape and wall structure, the species shows resemblance to pollen of Lagerstroemia flos-regina (Lythraceae) from which it differs, however, in the absence of distinct colpi. Lagerstroemia indica shows a comparable general shape and aperture structure which consists of circular pores without distinct ectexinous colpi, but differs in the verrucate-areolate sculpture of the tectum. Lagerstroemia speciosa (Plate VII, 5) is also similar in pore and 306
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wall structure and sculpture but is only weakly trilobate and has inconspicuous meridional ridges, while indistinct colpi are also present. Since there exists distinct affinity to the recent and fossil sonneratioid types it is considered more likely that Florschuetzia trilobata represents the extinct ancestor of the recent genus Sonneratia than that it is derived from a fossil Lagerstroemia species. FIorschuetzia semilobata nov. sp. (Plate VII, 6; holotype; Plate VII, 7, 8) Derivatio nominis: Name derived from the semilobate shape. Holotype: Slide TC-157, surface sample Dz-5007, northwestern Borneo. Description: Single grain, radially symmetrical, isopolar; prolate; in polar view lobate. Triporate, pores circular, 1-2 # in diameter, interlobate, endexinous (in less well preserved grains appearing as endexine + ectexine). Total wall thickness 1-2 # on poles and meridional ridges, probably < 1 # on porate fields; endexine -< ½/~ thick, columellae generally indistinct; tectum ± 1 # thick, areolateverrucate, coarser on meridional ridges, finer on porate fields, on poles often showing a transition to a psilate polar cap. Dimensions: 23-24/z. Variability: In size, coarseness and areal differentiation of sculpture. Some specimens show a rather evenly distributed sculpture while others show a differentiation along the meridional ridges or in poleward direction. Distribution: Virtually restricted to the uppermost part of the Magnastriatires howardi Zone and the Crassoretitriletes vanraadshooveni Zone in Borneo ( Florschuetzia levipoli Zone). Taxonomic affinities: The apertures and sculptural type clearly point to affinity with the pollen of Sonneratiaceae, but matching with a Recent species has not been possible. FIorschuetzia levipoli nov. sp. (Plate VII, 9; Plate VIII, 1; Plate VIII, 2; holotype) Literature: ?Santalumidites cainozoicus COOKSONet PIKE, 1954, p.209, pl.2, fig.71. Derivatio nominis: Name derived from the smooth polar caps. Holotype: Slide TC-158, surface sample Mq-ll91, northwestern Borneo. Description: Single grain, radially symmetrical, isopolar; prolate; in polar view circular to rounded triangular, sometimes bulging at equator. Triporate, pores circular, endexinous, in well preserved grains covered by thin ectexinous membrane, 2-8/z in diameter (depending on size grain). Total wall thickness ~z 2 #, generally thicker on poles than on equatorial area; endexine ~ 1/z thick; columellae mostly Rev. Palaeobotan. Palynol., 6 (1968) 189-348
307
indistinct, slightly enlarged (intra-areolate) on polar caps: tectum < 1 /~ thick, psilate on poles, broken up into a verrucate-areolate pattern on equatorial belt. Verrucae rounded-polygonal, of varying sizes, uniform height, regularly distributed. Dimensions: 30-50 /~ (averages) showing a distinct increase in size from older to younger strata. Variability: In thickness of tectum on poles and coarseness of verrucation on equatorial belt. The visibility of the columellate layer is mainly determined by the state of preservation. Occasionally the presence of a meridional ridge is suggested by folding of the grain but this feature is not structurally different from the remainder of the equatorial belt. Distribution: Regularly present in Borneo from the higher part of the Magnastriatites howardi Zone upwards (FIorschuetzia levipoli and F. meridionalis Zones). Remarks: The species is distinguished from Florschuetzia meridionalis by the absence of a structurally differentiated meridional ridge, the indistinct or even absent intra-areolate pattern on the polar caps and the generally smaller size. Compared to Florschuetzia semilobata, the psilate polar caps and circular or only weakly triangular shape in polar view are diagnostic. The relation between size and age will be discussed separately. Taxonomic affinities." Apart from the generally smaller mean size the species agrees in all essential characteristics with the pollen of Sonneratia caseolaris (Plate VIII, 3), a mangrove species at present growing in estuaries along the IndoMalesian coasts, Florsehuetzia meridionalis nov. sp. (Plate VIII, 4; holotype; Plate VIII, 5) Derivatio nominis: Name derived from the meridional orientation of the sculptural pattern. Holotype: Slide TC-159, surface sample Mq-1191, northwestern Borneo. Description: Single grain, radially symmetrical, isopolar; prolate; in polar view circular to rounded triangular. Triporate, pores circular, endexinous, in well
PLATE VIII 1. 2. 3. 4. 5. 6. 7.
Florschuetzia levipoli nov. gen., nov. sp., Borneo. Florsehuetzia levipoli nov. sen., nov. sp., Borneo, holotype. Sonneratia caseolaris (LINNAEUS) ENGLER, Recent. Florsehuetzia meridionalis nov. gen., nov. sp., Borneo, holotype. Florsehuetzia meridionalis nov. gen., nov. sp., Borneo. Sonneratia alba J. E. SMITH,Recent. Sonneratia alba J. E. SMITH, Recent.
Magnification × 1,000.
308
Rev. Palaeobotan. PalynoL, 6 (1968) 189-348
.
~
=iii=!=!=!!(iii=i ==
preserved grains covered by thin ectexinous membrane, 5-12/, in diameter. Total wall thickness ~: 3/~, generally thinner on porate fields; endexine < l #; columellae distinct on meridional ridge where thin, uniform and rather dense, on polar caps probably fused to form a typical intra-areolate pattern, not visible on porate fields. Tectum 1-1½ /, thick, psilate on polar caps, broken up into an areolatefossulate pattern on meridional ridges and into a verrucate pattern on porate fields. The meridional ridges are fairly sharply outlined against the porate fields, but merge gradually with the tectate-psilate polar caps. Dimensions: 35-60 # (averages) showing a distinct increase in size from older to younger strata. Variability: In thickness of tectum on poles and in coarseness of sculpture and structure. Distribution: Occurring in Borneo only, from the middle part of the Crassoretitriletes vanraadshooveni Zone upwards (FIorschuetzia meridionalis Zone). Remarks: The species is distinguished from Florschuetzia levipoli by the presence of a structurally differentiated meridional ridge and the distinct intraareolate structure of the polar caps and generally larger size. Taxonomic affinities: Apart from the generally smaller size of the Fossil assemblages, the species agrees in all essentials with the pollen ofSonneratia alba (Plate VIII, 6, 7), a mangrove species at present growing in estuaries along the Indo-Malesian, Indian and eastern African coastline. Genus Echitriporites VAN HOEKEN-KLINKENBERG, 1964
Echitriporites trianguliformis VAN HOZKEN-KLINKENBERG,1964 (Plate IX, 1, 2)
PLATE IX 1. Echitriporites trianguliformis VAN HOEKEN-KL1NKENBERG,Venezuela. 2. Echitriporites trianguliformis VAN HOEKEN-KLINKENBERG,Colombia. 3. Proteacidites dehaani nov. sp., Venezuela. 4. Proteacidites dehaani nov. sp., Colombia, holotype. 5. Guevina avellana MOLINA, upper focus, Recent. 6. Guevina avellana MOLINA, lower focus, Recent. 7, Lomatia ilicifolia R. BROWN, upper focus, Recent. 8. Lomatia ilicifolia R. BROWN, lower focus, Recent. 9. Anacolosidites cf. luteoides COOKSONet PIKE, New Guinea. 10. Anacolosidites cf. luteoides COOKSONet PIKE, Borneo. 11. Anacolosa frutescens BLUME, upper focus, Recent. 12. Anacolosa frutescens BLUME, lower focus, Recent. 13. Alnipollenites verus POTON1~, Borneo. 14. Alnus glutinosa (LINNAEUS)GAERTNER, upper focus, Recent. 15. Alnus glutinosa (LINNAEUS)GAERTNER, lower focus, Recent. Magnification × 1,000.
310
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Literature: Echitriporites trianguliformis VAN HO~KFN-KLINKEN~ERG,1964, p.218, pl.47, fig.7. Echitriporites trianguliformis BELSK¥, BOLTENHAGENet POTON~k, 1965, p.77, pl.13, fig. 22, 23. Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view semi-angular. Triporate, pores ectexinous and endexinous, circular, 2 # in diameter, costate, often slightly protruding. Endexine 4 1 /z , intectateechinate, echinae 1-2 ,u long, ~: 1 /z wide at base, conical or with rounded tops, 2/z apart. Dimensions: 21-30 #. Variability: Considerable variation exists in size and shape of the grain and in size and density of the spines. The more triangular grains with fewer and smaller spines are more common in the Upper Cretaceous of northern South America, whereas the more rounded grains with slightly more and larger spines are more common in the Eocene. However, since many transitional specimens occur, no specific distinction was possible. Distribution: Encountered in the Proxapertites operculatus Zone in all three areas, but rare in Borneo and soon disappearing. In the Caribbean area and Nigeria the species remains an important component of the Eocene microfloras which has great practical value for local correlations. In both areas it disappears from the record around the top of the Verrucatosporites usmensis Zone. Taxonomic affinities: Despite intensive search, no positive identification has been possible yet. This, and its gradual disappearance at the top of the Eocene suggest that the taxon producing the pollen grains is probably extinct. A superficial resemblance is shown by some Proteaceae (Embothrium, Garnieria, Persoonia, Telopea). Only Telopea oreades and Embothrium mucronatum were available for comparison but these species showed finely columellate-tectate pollen grains. Genus Proteacidites (COOKSON, 1950) ex COUPER, 1953
Proteacidites dehaani nov. sp. (Plate IX, 3; Plate IX, 4; holotype) Derivatio nominis: Named in honour of Mr. R. de Haan in recognition of his contribution to Venezuelan palynology. Holotype: Slide TC-160, surface sample E 1362, Colombia. Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view triangular. Triporate, pores ectexinous and endexinous, circular, 2~,/~ in diameter, costate. Total wall thickness ~ 1 ~t, endexine ½/z thick, columellae < ½ # thick and long; duplicolumellate, reticulate-foveolate tectum; muri -:~ ½/z high, ½/z wide, fiat topped; lumina 1-1½/z wide, of variable shape, coarser on interporate fields, finer on poles and around pori. 312
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
Dimensions: 32-36/~. Variability: Ornamentation varying from reticulate-foveolate to perforate. Constant are size and shape, pore structure and the coarser sculpture on the interporate areas and the species is well characterized by these features. A comparable but not identical type is known from the post-Eocene of western Venezuela. Comments: The species appears different from reticulate members of the genus described by COOKSON (1950), COUPER (1953) and HARRIS (1965) mainly because of size, straight sides and duplibaculate muri. It is rather similar to Proteacidites thalmanni ANDERSON, 1960, from which it differs, however, in its larger size, absence of "notched" pores and presence of duplicolumellate muri. Distribution: In the Caribbean area and in Nigeria restricted to the lower part of the Proxapertites operculatus Zone and principal marker for the Proteacidites dehaani Zone. Taxonomic affinities: Close resemblance exists with pollen of Guevina avellana (Proteaceae, Chili, Plate IX, 5, 6). Other Proteaceae are more or less different: Lomatia ilicifolia (Chili, Australia, Plate IX, 7, 8) has smaller lumina, Cardwellia sublimis (Queensland) differs in its more rounded, non-costate pores. Stenocarpus sinuatus (Australia) is less distinctly multicolumellate and has a much thicker wall, Leucospermum hypophyllum (southern Africa) has smaller lumina and Symphionema montanum (Australia) has a much smaller size.
Class Stephanoporatae IVERSENet TROELSSMITH, 1950 Genus Anacolosidites (CooKSON et PIKE, 1954) ex R. POTONI~, 1960 Anacolosidites cf. luteoides COOKSON et P1KE, 1954 (Plate IX, 9, 10) Literature: cf. Anacolosidites luteoides COOKSON et P~KE, 1954, p.207, pl.1, fig.47-50. Description: Single grain, radially symmetrical, isopolar, oblate; subtriangular outline in polar view; pores arranged in two groups of three, opposite each other, each at a distance of :L 3 # from the equator, probably ectexinous and endexinous, 4½ /~ in diameter, equatorially elongated with slightly thickened borders; endexine ½ # thick at angles, up to 2/t thick at straight sides of equator; columellae simple, < 1 /~ thick at angles, 1 ,u thick at straight sides of equator; tectum uniformly < ½ # thick, psilate. Dimensions: 18-33 ,u. Variability: In size and wall thickness. Comments: It would seem that Cookson and Pike's species A. luteoides comes closest to the specimens described here and this name is adopted provisionally, pending further study. Rev. Palaeobotan. Palynol., 6 (1968) 189-348
313
Distribution: In Borneo and Nigeria already recorded from the Paleocene part of the Proxapertites operculatus Zone, but in the Caribbean area appearing later at the base of the Retibrevitricolpites triangulatus Zone (base Eocene). In the Caribbean area the species disappears from the record already at the top of the Retitricolporites guianensis Zone, in Nigeria it is found higher, up to the youngest part of the Magnastriatites howardi Zone, while in Borneo it remains common throughout the Tertiary. Taxonomic affinities: Close correspondence exists with pollen grains of Anacolosa (Plate IX, 11, 12), Cathedra and Ptychopetalum (Olacaceae). Genus Alnipollenites R. POTONI~, 1931
A&ipollenites verus (R. POTONI~, 1931) ex R. POTONI~, 1934 (Plate IX, 13) Literature." AInipollenites verus R. POTONII~, 1934, p.58, pl.2, fig. 17. Stephanoporitesfornicatus VAN DER HAMMEN, 1956b, p.94, pl.10, fig.3Y
Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view subangular. 3-6 ectexinous and endexinous pores, 3-4 # wide, slightly vestibulate; pores connected by arci; endexine <:~ 1 # thick, ectexine 1 /z thick, columellae indistinct, tectum smooth or finely granulate. Dimensions: 28-31 /~. Variability: The pore number is the main variable, five being the average. Distribution." In the Caribbean area occurring from the base of the Alnipollenites verus Zone upwards. In Borneo present from the upper part of the Verrucatosporites usmensis Zone to the top of the Crassoretitriletes vanraadshooveni Zone (MULLER, 1966). Taxonomic affinities: Close correspondence exists with Alnus pollen (Plate IX, 14, 15). Genus Pachydermites nov. gen.
Derivatio nominis: Name derived from the thick exine. Diagnosis: Stephanoporate grains with 4-6 rather irregularly shaped aper-
PLATE X 1. Echiperiporites estelae nov. sp., Borneo, holotype. 2. Pachydermites diederixi nov. gen., nov. sp., Nigeria, holotype. 3. Symphonia globtdifera LINNAEUS (ill.), Recent.
Magnification × 1,000.
314
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PLATE X
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
315
tures, which are larger in the endexine than in the ectexine, a very thick endexine, which is finely perforated around apertures and a thin tectate-psilate ectexine. Type species: Pachydermites diederixi nov. sp. Pachydermites diederixi nov. sp. (Plate X, 2; holotype) Derivatio nominis: Named in honour of Mr. D. O. J. Diederix in recognition of his contributions to Colombian and Nigerian palynology. Holotype: Slide TC-161, well Ughelli-3, 5200 ft., Nigeria. Description: Single grain, radially symmetrical, isopolar, oblate-suboblate. 4-6 porate, ectexinous apertures 6-10 /~ long, 4-9 /~ wide, almost circular and irregular in outline, endexinous apertures of identical shape, but slightly larger and somewhat vestibulate. Endexine 3-6 # thick, irregularly perforated around apertures. Interior surface irregularly verrucate; columellae ½/~ thick and long; tectum ½ # thick, psilate. Dimensions: 46-68/~. Variability: In size and coarseness of wall. Distribution: In Nigeria known from the base of the Monoporites annulatus Zone upwards, but in Venezuela occurring only from the base of the Grimsdalea magnaclavata Zone up wards. Taxonomic affinities." Identical with the pollen of Symphonia globulifera (Guttiferae, Plate X, 3). As far as known this pollen type does not occur in other genera and the identification has a very high degree of probability. Unfortunately the pollen of the Madagascar species of this genus have not yet been described.
Class Periporatae IVERSENet TROELSSMITH, 1950 Genus Buttinia BOLTENHAGEN, 1967 Buttinia andreevi BOLTENHAGEN, 1967 (Plate XI, 2, 3) Literature: "type S 231", JARDINI~and MAGLOIRE, 1965, p.208, pl.V, fig. 8. Buttinia andreevi BOLTENHAGEN, 1967, p.342, pl.lI, fig.5-7.
PLATE XI 1. The~pesiapopulnea COgREA,Recent. 2. Buttinia andreevi BOLTENHAGEN,Colombia, upper focus. 3. Buttiniaandreevi BOLTENHAGEN,Colombia, lower focus. Magnification × 1,000. 316
Rev. Palaeobotan.PalynoL, 6 (1968) 189-348
P L A T E XI
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
317
Description: Single grain, centro-symmetrical, isopolar, spherical. Apertures 20 or more, ectexinous and endexinous, rounded to angular, 7-10 # wide, 3-5/~ apart. Endexine 2 / , thick; columellae <-. I # long, < ½ # thick, only visible in well preserved grains; tectum reduced to rounded ridges, ½/~ thick, 1½-2 # wide, between the pores, psilate. Dimensions." 40-55/z. Variability: There is only slight variability in size and wall thickness. Comments: This species has already been described and figured without naming from the Senonian of western Africa by JARDIN~ and MAGLOIRE(1965) and was recently named by BOLTENHAGEN(1967). None of these authors has observed the presence of columellae and tectum, which in our opinion proves angiospermous affinities and permits the assignment to the class Periporatae. Distribution." Both in Nigeria and the Caribbean area restricted to the Proteacidites dehaani Zone. In Senegal and Gabon also restricted to the Senonian. Not recorded from Borneo. Taxonomic affinities: Unknown. Genus Echiperiporites VAN DER HAMMENet WYMSTRA,1964
Echiperiporites estelae nov. sp. (Plate X, I; holotype) Derivatio nominis: Named in honour of Mrs. Estela Bradley de Giacomo in recognition of her contribution to Venezuelan palynology. Holotype: Slide TC-162, surface sample MQ-1189, northwestern Borneo. Description: Single grain, centro-symmetrical, isopolar, spherical; periporate, pores 20-24, ectexinous and endexinous, slightly annulate, annuli 1½-2 # wide; pores 4-6 # wide, 10-12/~ apart. Endexine 1 ~ thick; columellae ~z ½/~ thick, ~ 1 /~ long; tectum smooth, -:< 1/~ thick, thickened at roots of spines; spines 6-9 # long, 2-4/~ thick at base, conical, blunt, 6-10/~ apart. Dimensions." 55-87/~, excluding spines. Variability: The species as defined here shows considerable variation in size, coarseness of wall structure and spines, density of spines and in number of pores. Distribution: The oldest occurrences are known from the Caribbean area where the species starts in the middle of the Eocene (Verrucatosporites usmensis Zone). In Nigeria the species is very rare and known virtually only from the Magnastriatites howardi Zone upwards. In Borneo it is occurring regularly in the Echitricolporites spinosus and Crassoretitriletes vanraadshooveni Zones and is probably absent in earlier periods. Taxonomic affinities: Due to the rather large variability of this species it is difficult to indicate the taxonomic affinity with certainty. The majority of the 318
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
specimens agree well with pollen of Thespesia populnea (Malvaceae, Plate XI, 1), but larger grains could be more related to Hibiscus tiliaceus (Malvaceae). Ipomoea pollen grains have generally more pores and are more densely spinose, but otherwise belong to this group of species. Class Fenestratae IVERSEN et TROELS SMITH, 1950 Genus Fenestrites (VAN DER HAMMEN, 1956b)
Lectogenotype: Fenestrites spinosus VAN DER HAMMEN, 1956b. Remarks: Since Van der Hammen has invalidly indicated a recent pollen grain as type specimen, his genus is hereby legalized by selecting as lectogenotype the fossil species as described below. Fenestrites spinosus ex VAN DER HAMMEN, 1956b (Plate XII, 1) Literature: Fenestrites spinosus VAN DER HAMMEN, 1956b, p.97, pl.12, fig.38. Description: Single grain, radially symmetrical, isopolar, spherical; outline In polar view almost hexangular. Colpi and pori indistinct, probably tricolporate. Exine differentiated into a pattern of intectate lacunae (fenestrae), 8-11 /~ wide and tectate-columellate cristae. Columellae 1½ # long, ½/z thick; cristae 1-1½ # wide, 1/t high, bearing single rows of spines, 2 # long, 1 # wide at base. Dimensions: 30-38 # (including cristae, excluding spines). Variability: In size and coarseness of ornamentation. Sometimes undulating cristae have been observed. Distribution: Restricted to the middle and upper part of the Echitricolporites spinosus Zone. More frequently observed in the Caribbean area than elsewhere. Taxonomic affinities: This species is typical for the liguliflorae pollen type of the Asteraceae (Compositae), which is produced by a large number of genera. Of the many species which produce this pollen type, the following only will be mentioned as coming close to the fossil grains: Elephantopus angustifolia, Rolandia fruticosa (Plate XII, 3), Vernonia canescens, Vernonia remotiflora (Plate XII, 2). Class Tricolpatae IVERSEN et TROELS SMITH, 1950 Genus Striatricolpites (VAN DER HAMMEN, 1956b) ex GONZALEZ, 1967
Striatricolpites catatumbus GONZALEZ, 1967 (Plate XII, 4) Rev. Palaeobotan.Palynol., 6 0968) 189-348
319
Literature: Striatricolpites catatumbus GONZALEZ, 1967, p.30, pl. VIII, fig.7. Description: Single grain, radially symmetrical, isopolar, prolate; outline
in polar view trilobate to spherical. Tricolpate, colpi ectexinous, long, intruding with straight simple borders and pointed ends. Pores absent or indistinct. Endexine 1 # thick, columellae simple, ½ # long and ½/~ thick, slightly longer on poles, linearly arranged underneath striae of tectum; tectum striate; striae 1 # thick, 1-1½/~ wide, 1 # apart, subparallel or slightly anastomosing; between striae tectum very thin, sometimes finely perforate. Dimensions: 33-50/~. Variability: Some variability exists in size and in coarseness of wall structure and presence or absence of indistinct pores. The specimens described here agree in all respects with Gonzalez' type material. Tricolpate striate types described by MULLER (1968) from the uppermost Cretaceous of Borneo are considered to be specifically distinct. Distribution: Both in the Caribbean area and in Nigeria occurring from the base of the Retibrevitricolpites triangulatus Zone upwards. In Borneo the lower limit is not exactly known, but a related species occurs already in the Paleocene. Taxonomic affinities: Closest resemblance is with pollen of the genus Crudia (Fabaceae, Plate XII, 5, 6), but Anthonotha and Isoberlinia (Fabaceae) have similar pollen. Macrolobium bifilium (Fabaceae) has a much coarser striate pattern but is otherwise similar. It is not yet possible to be more precise about the affinities of this rather variable pollen species. Genus Perfotricolpites GONZALEZ, 1967 Perfotricolpites digitatus GONZALEZ, 1967
(Plate XII, 10) Literature: Perfotricopites digitatus GONZALEZ, 1967, p.34, pl.VI, fig. 1. Description: Single grain, radially symmetrical, isopolar, prolate. Tricolpate:
PLATE XII Fenestrites spinosus VAN DER HAMMEN,Venezuela. Vernonia remotiflora L. C. RICHARD,Recent. Rolandia fruticosa (LINNAEUS)KUNTZE,Recent. Striatricolpites catatumbus GONZALEZ,Colombia. Crudia amazonica SPRUCE, upper focus, Recent. Crudia amazonica SPRUCE, lower focus, Recent. Foveotricolpites perforatus VAN DERHAMMENet GARCIA,Venezuela, upper focus. Foveotricolpites perforatus VANDERHAMMENet GARCIA,Venezuela, lower focus. Foveotricolpites perforatus VANDERHAMMENet GARCIA,Venezuela. 10. Perfotricolpites digitatus GONZALEZ,Venezuela. 1. 2. 3. 4. 5. 6. 7. 8. 9.
Magnification × 1,000. 320
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
PLATE
XII
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~ Rev. Palaeobotan. Palynol., 6 (1968) 189-348
l
O 321
colpi ectexinous, long, strongly intruding, with straight borders and pointed ends. Pores very indistinct, if present endexinous. Endexine ½ /~ thick; columellae digitate, 2-2½/~ long, 1 p thick at base, ½ I~ thick at top of branches; tectum thin, finely reticulate-perforate, lumina ~ ½ ~ in width. Dimensions: 46-70 #. Variability: Occasionally in Venezuela pericolpate specimens are found, which because of the very typical wall structure should be included in the species. Whether some specimens observed in Nigeria with large round endexinous pores should be included is more doubtful. Distribution: Both in the Caribbean area and Nigeria occurring for the first time approximately at the base of the Verrucatosporites usmensis Zone, but, while continuously present in the former area up to Recent, in Nigeria disappearing from the record in the upper part of the Magnastriatites howardi Zone. In Borneo present at least from the base of the Echitricolporites spinosus Zone upwards. Taxonomic affinities: The pollen grains of Merremia glabra (Plate XIII, 2) and M. umbellata (Convolvulaceae) are rather similar. Identification of the fossil dispersed pollen with Merremia appears fairly reliable. Branched columellae are also found in Scaevola (Goodeniaceae, Plate XIII, 1) the pollen of which differs in the presence of costate endexinous pores and much thicker wall on poles. Valerianella stenocarpa (Valerianaceae) has also slightly similar pollen. Genus Foveotricolpites VAN DER HAMMEN et QARCIA, 1966 Foveotricolpites perforatus VAN DER HAMMEN et GARCIA, 1966 (Plate XII, 7, 8, 9) Literature: Foveotricolpites perforatus VAN DER HAMMEN et GARCIA, 1966, p.l12, fig.18. Description: Single grain, radially symmetrical, isopolar, subprolate. Tricolpate, colpi ectexinous, medium long, with straight borders and pointed ends. Endexine < 1 # thick; columellae ½-1 # thick and long, tightly packed in an irregular pattern; tectum 1 # thick, foveolate; lumina rounded oval, 1-2/~ wide, coarser, up to 3# wide on poles, approx. 3/~ apart.
PLATE XIII 1. Scaevola plumieri VAI4L,Recent. 2. Merremia glabra HALUER(ill.), Recent. 3. Stephanoeolpites eostatus VAN DER HAMMEN, Venezuela. 4. Tabernaemontana attenuata URBAN,upper focus, Recent. 5. Tabernaemontana attenuata URBAN,lower focus, Recent. 6. Gemmastephanocolpites gemmatus VAN DER HAMMENet GARCIA,polar view, Venezuela. 7. Gemmastephanocolpites gemmatus VAN DER HAMMENet GARCIA,equatorial view, Venezuela. Magnification × 1,000. 322
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
.........
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Dimensions: 44--64/z. Variability: A well characterized species with some variability in size and coarseness of wall structure. Distribution: Restricted to the Foveotricolpites perforatus Zone of the Caribbean area. Taxonomic affinities: Unknown.
Class Stephanocolpatae IVERSENet TROELS SMITH, 1950 Genus Stephanocolpites (VAN DER HAMMEN, 1954) ex R. POTONII~, 1960
Stephanocolpites costatus VAN DER HAMMEN, 1954 (Plate XIII, 3)
Literature: Stephanocolpites costatus VAN DER HAMMEN, 1954, p.92, pl.7, fig.9.
Remarks: The original short diagnosis is here enlarged. The identity of the specimens described by us has been confrmed by Van der Hammen. Description: Single grain, radially symmetrical, isopolar, spherical; outline in polar view circular. Apertures 5-6; ectexinous, 10-12 # long colpi and one fused circular endexinous aperture which is distinctly costate. Endexine < ½ p thick, columella < ½ # long, < ½/~ thick; tectate-foveolate, tectum < ½/t thick, lumina oval to circular up to 1 # in diameter, coarser on poles, muri rounded, 1-1½/~ wide. Dimensions: 35-45 #. Variability: Only slightly variable in size and sculpture and distinctness of colpi. Distribution: Restricted to the lower part of the Proxapertites operculatus Zone in the Caribbean area (top in Ctenolophonidites lisamae Zone). Taxonomic affinities: Unknown. A similar aperture combination has, however, been found in Tabernaemontana attenuata (Apocynaceae, Plate XIII, 4, 5), the wall structure of which is much finer reticulate, while the equatorial endexinous aperture is much wider and less costate. Genus Gemmastephanocolpites VAN DER HAMMENet GARCIA, 1966
Gemmastephanocolpites gemmatus VAN DER HAMMENet GARCIA, 1966 (Plate XIII, 6, 7) Literature: Gemmastephanocolpites gemmatus VAN DER HAMMENet GARCIA, 1966, p.110, fig.12. 324
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
Description: Single grain, radially symmetrical, isopolar, spherical; outline in polar view circular. Apertures 5-6; ectexinous, 10-12 /t long colpi and one fused circular endexinous aperture which is distinctly costate. Endexine < 1 /~ thick, columellae < 1 /~ long, ½/~ thick; tectum smooth, covered with verrucae or gemmae 1-2/~ in diameter, 1 /~ thick, generally situated on top of columellae, but rather irregularly distributed. Dimensions: 33-42 #. Variability: In size and coarseness of sculpture. Distribution: Restricted to the Ctenolophonidites lisamae and the Foveotricolpites perforatus Zones in the Caribbean area. Taxonomic affinities: No comparable Recent plant species is known, but the distinct resemblance with Stephanocolpites costatus and its occurrence at a stratigraphically higher level suggest a phylogenetic relationship between the two. Genus Retistephanocolpites LEIDELMEYER,1966
Retistephanocolpites williamsi nov. sp. (Plate XIV, 1, 2; holotype) Derivatio nominis: Named in honour of Mr. R. W. Williams in recognition of his contribution to Nigerian palynology. Holotype: Slide TC-163, well Ubulu-1, 3000 ft., Nigeria. Description: Single grain, radially symmetrical, isopolar, oblate. 6-7 colpate, colpi ectexinous, 14 # long. Wall 221--4/z thick; endexine 1-2½/z thick, columellae 1 # long and thick, irregularly arranged and forming a spongy structure; tectum < 1 /z thick, reticulate-foveolate; lumina oval to circular 1-2 # in diameter, muri 1 # wide. Dimensions: 4 1 4 7 #. Variability: There exists considerable variation in the coarseness of the sculpture and some in the thickness of the endexine. D&tribution: Absent in the Caribbean area, in Nigeria occurring from the base of the Proxapertites operculatus Zone upwards to the middle of the Verrucatosporites usmens& Zone. In Borneo known from the Neogene, base not exactly known. Taxonomic affinities: The combination of 5-6 short apertures, spongy columellate structure and reticulate-foveolate tectum is so far only known from Ctenolophon parvifolius (Ctenolophonaceae, Plate XIV, 3, 4) which differs only in the 2-3/z wide muri. Identification with this Indo-Malesian species appears highly probable. Genus Cteno/ophonidites VAN HOEKEN-KLINKENBERG,1966
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
325
Ctenolophonidites costatus (VAN HOEKEN-KLINKENBERG, 1964) ex VAN HOEKENKLINKENBERG, 1966 (Plate XIV, 5, 6) Literature: KUYL et al. (1955, p.2, fig.10, 12, 13). Stephanocolpites costatus VAN HOEKEN-KLINKENBERG, 1964, p.221, pl.4, fig.10. Ctenolophonidites costatus VAN HOEKEN-KLINKENBERG, 1966, p.42. Description: Single grain, radially symmetrical, isopolar, spherical-oblate; 6-colpate; colpi ectexinous, 24 # long, slightly costate equatorially. Ectexine locally thickened into a pattern of radial costae, meeting near the poles and forming ring-like ridges, occasionally with extra ridges inside these rings; ridges 1½-2 # high, 5 p wide. Columellae and tectum not differentiated, wall psilate, 3-4½ p thick at equator and apparently densely and finely perforated in all directions, creating a spongy effect which diffuses the light considerably. Dimensions: 37-50 #. Variability: In size and coarseness of wall structure. Distribution: Only known from Nigeria where the species already occurs in the Proteacidites dehaani Zone, is temporarily absent in the higher part of the Proxapertites operculatus Zone, to be present again from the base of the Monoporites annulatus Zone up to Recent. Taxonomic affinities: Agrees in all essential details with the pollen of Ctenolophon engleri (Ctenolophonaceae, Plate XV, 1,2) except its smaller size. This pollen type is not known from any other plant as yet (cf. also SAAD,1962). Ctenolophonidites lisamae (VAN DER HAMMEN et GARCIA, 1966) nov. comb. (Plate XIV, 7, 8) Literature: Scabrastephanocolpites lisamae VAN DER HAMMEN et GARCIA, 1966, p.ll0, fig.14.
PLATE XIV 1. Retistephanocolpites williamsi nov. sp., Nigeria, holotype, upper focus. 2. Retistephanocolpites williamsi nov. sp., Nigeria, holotype, lower focus. 3. Ctenolophon parvifolius OLIVER,upper focus, Recent. 4. Ctenolophon parvifolius OUVER,lower focus, Recent. 5. Ctenolophonidites costatus VAN HOEKEN-KLINKENBER~,Nigeria, upper focus. 6. Ctenolophonidites costatus VAN HOEKEN-KUNKENaERG,Nigeria, lower focus. 7. Ctenolophonidites lisamae VAN DER HAMMENet GARC~A,Venezuela, polar view. 8. Ctenolophonidites lisamae VAN DER HAMMENet GARCIA,Venezuela, equatorial view. Magnification × 1,000.
326
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
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Description: Single grain, radially symmetrical, isopolar, spherical-suboblate; outline in polar view stellate-circular. 5-colpate, colpi 14 .u long, ectexinous, slightly costate equatorially. Ectexine locally thickened into a pattern of radial costae, joining in pairs around the terminations of the colpi, not touching near poles; ridges 12~--2bt high, 2-3 ,u wide. Columellae and tectum not differentiated; wall finely scabrate, 3-4½ # thick at equator, apparently densely perforated in all directions, creating a spongy effect which diffuses the light considerably. Dimensions: 17-31 #. Variability: Some variability is present in the way in which the ridges unite with each other. Comments: In view of the close relationship which exists between this species and Ctenolophonidites costatus, we have transferred it to the latter genus. The identity of our specimens has been confirmed by Van der Hammen. Distribution: Virtually restricted to the Ctenolophonidites lisamae and Foveotricolpites perforatus Zones in the Caribbean area. Taxonomic affinities: Has in all probability been derived from an extinct species of Ctenolophon (Ctenolophonaceae).
Class Tricolporatae |VERSEN et TROELS SMITH, 1950 Genus Psilatricolporites (VAN DER HAMMEN, 1956) ex VAN DER HAMMENet WYMSTRA, 1964
Psilatrieolporites operculatus VAN DER HAMMENet WYMSTRA, 1964 (Plate XV, 3)
Literature: Psilatricolporites operculatus VAN DER HAMMEN et WYMSTRA, 1964, p.236, pl.1, fig. 13. Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view circular to slightly semi-angular. Tricolporate; colpi long, ectexinous,
PLATE XV 1. 2. 3. 4. 5. 6. 7. 8. 9.
Ctenolophon engleri MILDBREAD, upper focus, Recent. Ctenolophon engleri MILDBREAD, lower focus, Recent. Psilatricolporites operculatus VAN DER HAMMENet WYMSTRA, Surinam. Alchornea cordifolia MUELLER-ARG., Recent. Alckornea obovata PAX et HOFFMANN, Recent. Zonocostites ramonae nov. gen., nov. sp., Borneo, holotype. Zonocostites ramonae nov. gen., nov. sp,, Borneo, holotype. Rhizopkora rnucronata LAMARCK,upper focus, Recent. Rhizophora mucronata LAMARCK,lower focus, Recent.
Magnification × 1,000. 328
Rev. Palaeobotan.Palynol., 6 0968) 189-348
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marginate and provided with distinct opercula of identical structure as found in margins; opercula 1½ # wide at equator; pores distinct only in equatorial view, endexinous, equatorially elongated with indistinct borders. Endexine ~ ½/~ thick; columellae < ½ # thick and long, slightly larger at margins of colpi; tectum ~( ½ # thick, finely perforate, but ~ ½/~ thick and less finely perforate at margins of colpi. Dimensions: 17-28 #. Variability: Margins of colpi vary in extent and thickness. Distribution: In the Caribbean area present from the base of the Psilatricolporites operculatus Zone upwards. In Nigeria the first occurrence is slightly higher, at the base of the Verrucatosporites usmensis Zone. In Borneo this species is regularly present in the Neogene, but its base has not yet been defined. Taxonomic affinities: This species shows a striking resemblance to the pollen of the genus Alchornea (Euphorbiaceae). The pollen of Alchornea cordifolia (Plate XV, 4) is very similar, that ofA. obovata (Plate XV, 5) and A.javanensis has smaller colpi and opercula, but larger margins. Psilatricolporites crassus VAN DER HAMMEN et (Plate XVI, 1, 2)
WYMSTRA,
1964
Literature: Psilatricolporites crassus VAN DER HAMMEN et WYMSTRA, 1964, p.237, pl.1, fig. 1-4. Description: Single grain, radially symmetrical, isopolar, spherical to subprolate; outline in polar view circular. Tricolporate; colpi medium long, ectexinous, straight with pointed ends; pores endexinous, equatorially elongated, oval or slitshaped, 15-19 # long, distinctly costate, costae 5 # wide and up to 4½ # thick, parallel to the pores. Endexine 1½/z thick, columellae ½ # thick and 1 /z long, tectum psilate to finely perforate-foveolate, 1-1½/z thick.
PLATE XVI 1. Psilatricolporites crassus VAN DER HAMMENet WYMSTRA,Nigeria. 2. Psilatricolporites crassus VAN DER HAMMENet WYMSTRA,Venezuela. 3. Hura crepitans LINNAEUS, upper focus, Recent. 4. Hura crepitans LINNAEUS, lower focus, Recent. 5. Verrutricolporites rotundiporis VAN DER HAMMENet WYMSTRA, Trinidad. 6. Verrutricolporites rotundiporis VAN DER HAMMENet WYMSTRA,Surinam. 7. Verrutricolporites rotundiporis VAN D~R HAMMENet WYMSTRA, Nigeria. 8. Crenea maritima AUBLET, Recent. 9. Crenea maritima AUBLET, upper focus, Recent. 10. Crenea maritima AUaLE'r, lower focus, Recent. 11. Echitricolporites spinosus VAN DER HAMMEN, upper focus, Venezuela. 12. Echitricolporites spinosus VAN DER HAMMEN, lower focus, Venezuela. 13. Riencourtia glomerata CASS, upper focus, Recent. 14. Riencourtia glomerata CASS, lower focus, Recent. Magnification × 1,000.
330
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
PLATE XVI
Dimensions: 41-70 ,u. Variability: This species is very variable in size, thickness of wall, especially the endexine, dimensions of columellae and width of the perforations. It is, moreover, susceptible to corrosion of the tectum, which may lead to pseudo-ornamentations such as areolate sculpture with widely spaced irregular grooves, geminate sculpture with deep grooves, verrucate sculpture, densely intersected by grooves or scabrate sculpture with the columellae protruding through membrane-thin remnants of the tectum. Distribution: In the Caribbean area and in Nigeria occurring from the base of the Retibrevitricolporites triangulatus Zone upwards, in the Caribbean area up to the Recent, but in Nigeria not known at present (except introduced). Absent from Borneo. Taxonomic affinities: Closest resemblance is with pollen of the tropical American genus Hura (Euphorbiaceae) in which the tectum is not perforatefoveolate as in the fossil species, but psilate. Hura polyandra is very similar in its apertures, but in the pollen of Hura crepitans (Plate XVi, 3, 4) the ectexinous colpi are much longer than is found in Psilatricolporites crassus. The pollen types found in Sapium (Euphorbiaceae) are more different. It is possible that the fossil species may represent an extinct species of Hura or that the pollen type of this genus may have changed its appearance slightly. The dominance of Hura crepitans at present in the Caribbean coastal environment forms a strong additional argument for assigning the fossil species to Hura. However, the absence of Hura in the present day natural vegetation of Nigeria (Hura senegalensis is, according to HUTCHINSON and DALZIEL (1954) probably imported) casts doubt on the affinities of the Nigerian grains assigned to the species. Recently LANGENHEIMet al. (1967) have described a fossil pollen closely resembling that of Pelliciera rhizophorae (Theaceae) from the Oligo-Miocene of Chiapas (Mexico). The resemblance to some variations of PsilatricoIporites crassus is striking indeed and the possibility that this monotypic mangrove genus had formerly a much wider range is worth further investigation. Genus Zonocostites nov. gen.
Derivatio nominis: Name derived from the costate endexinous apertures. Diagnosis: Spherical to subprolate, tricolporate; colpi relatively short, endexinous apertures equatorially elongated or almost fused, distinctly costate; wall tectate, finely perforate, thin, often almost psilate on equator, or thicker at poles, due to longer columellae. Type species: Zonocostites ramonae nov. sp. Remarks: This genus is intended to accommodate fossil dispersed pollen of the Rhizophora-Bruguiera type.
332
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
Zonocostites ramonae nov. sp. (Plate XV, 6; holotype; Plate XV, 7) Literature: Rhizophora-type MULLER 1964, p.37, pl.I, fig.3. Derivatio nominis: Named in honour of Miss Ramona Henriquez in recognition of her contribution to Venezuelan palynology. Holotype: Slide TC-164, well CO-77, 3600 ft., Trinidad. Description: Single grain, radially symmetrical, isopolar, spherical. Tricolporate, colpi ectexinous, medium long, straight with pointed ends, slightly costate, endexinous apertures equatorially elongated to almost fused, distinctly costate, in polar view slightly vestibulate. Endexine ~ ½/z thick; columellae < ½ # thick and high; tectum < ½ # thick, densely perforate, coarser on poles and finer to almost psilate on equatorial belt, perforations < ½/~ wide. Dimensions: 16-19 bt. Variability: This is a very variable species, especially in size and coarseness of structure and perforations on the poles. Attempts to separate subtypes corresponding to Recent species of Rhizophoraceae have been unsuccessful. Distribution: The earliest positive occurrences of Zonocostites ramonae are known from the Verrucatosporites usmensis Zone in the Caribbean area, with doubtful ones from the Monoporites annulatus Zone. In Nigeria the first appearances are later and occur around the base of the MagnastriatiteshowardiZone. In Borneo Eocene sediments unfortunately do not carry well enough preserved microfloras to permit positive identification, but in the Verrucatosporites usmensis Zone the species does occur. These pre-Miocene occurrences are all in low frequencies. Approximately at the Oligo-Miocene transition (lower part of the Magnastriatites howardi Zone) in all three areas a distinct quantitative increase can be observed and the species remains dominant in the coastal and marine sediments of the whole tropics up to Recent. Taxonomic affinities: The rather wide limits adopted for this species include the pollen types produced by the various species of the genera Rhizophora (Plate XV, 8, 9), Bruguiera, Ceriops, and Carallia (Rhizophoraceae). Specific differences exist, but in general the preservation of the fossil grains does not allow their recognition. Confusion with pollen of other taxa appears unlikely, however. Genus Verrutricolporites VAN DER HAMMENet WYMSTRA,1964
Verrutricolporites rotundiporis VAN DER HAMMENet WYMSTRA,1964 (Plate XVI, 5, 6, 7) Literature: Verrutricolporites rotundiporis VAN DER HAMMEN et WYMSTRA, 1964, p.237, pl.I, fig.14.
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
333
Description: Single grain, radially symmetrical, isopolar, spherical to subprolate; outline in polar view lobate. Tricolporate, apertures interlobate; colpi ectexinous, indistinct, medium long, intruding; pores endexinous, circular, 2-3/z in diameter, sharply outlined. Total wall thickness approx. 1 /~; endexine ~ ~/~ thick, columellae thin, but generally clearly visible, straight, ½ /z long; tectum ½ # thick, psilate or covered by low, irregularly shaped verrucae, 1-2 # in diameter and up to ½/~ high. Dimensions: 15-24 ~u. Variability: Mainly in the development of the verrucate sculpture. All transitions between almost psilate and strongly verrucate grains can be observed and it has proved impossible to arrive at a separation between a psilate and a verrucate type, in conformity with Van der Hammen and Wymstra's experience. The ectexinous furrows are only rarely clearly outlined and, when the grains are folded together, mostly hidden between the lobes. Comments: Our description agrees well with the one given by VAN OER HA~aMEN and WVMSa'RA (1964), but we would stress in addition the trilobate condition, which often causes the compressed grains to assume a characteristic folded appearance with the pores often half hidden by the folds. There is evidence for a gradual increase in degree of verrucation from older to younger strata, but the phenomenon is not clear enough to be used for stratigraphical interpretation without detailed statistical analysis. A comparable degree of variation may exist in the genus Crenea which has probably produced the fossil species. There exists some superficial similarity with FIorschuetzia trilobata, the points of difference being the smaller size, distinct columellae, tectate-verrucate sculpture with equal wall thickness over the entire grain in Verrutricolporites rotundiporis. Distribution: In the Caribbean area the first occurrences are around the base of the Magnastriatites howardi Zone; it is very abundant in the coastal and marine sediments of the Verrutricolporites rotundiporis Zone and afterwards decreases in numbers. In Nigeria the first occurrence is at the base of the Verrutricolporites rotundiporis Zone. In the Caribbean area present up to the present day, in Nigeria scattered rare occurrences from the base Echitricolporites spinosus Zone. Absent from Borneo. Taxonomic affinities: The pollen of Crenea maritima (Plate XVI, 8, 9, 10) agrees in all essential details with Verrutricolporites rotundiporis, but is more variable. Investigation of Crenea pollen from various localities revealed a variability in degree of verrucation which is paralleled in the fossil material. However, in view of the stratigraphical trend towards increased verrucation, one might expect the recent relatives to show the highest degree of verrucation and this is definitely not the case. It may be mentioned here that, according to information kindly supplied by Prof. F. P. Jonker, Utrecht, several species of Crenea described from the tropical South American coastline are considered by him to be synonyms of Crenea maritima, with the possible exception of Crenea patentinervis STANDLEV, 334
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
1947, of which unfortunately no material was available for comparison. The dominance of Verrutricolporites rotundiporis in coastal and marine sediments is in agreement with the present day habitat of Crenea, growing in swampy places along river courses and in the mangrove vegetation. Some superficial resemblance exists with the pollen of Sonneratia apetala, but this is considerably larger, has no ectexinous colpate apertures and shows a graded development in the verrucate sculpture which is coarser on poles. Genus Echitricolporites VAN DER HAMMEN, 1956b. Lectogenotype: Echitricolporites spinosus VAN DER HAMMEN, 1956b
Remarks: The genus is here validated by selecting a lectogenotype, since Van der Hammen has invalidly indicated the pollen of a Recent species as genotype.
Echitricolporites spinosus VAN DER HAMMEN, 1956b (Plate XVI, 11, 12)
Literature: Echitricolporites spinosus VAN DER HAMMEN, 1956b, p.92, pl.10, fig.30.
Remarks: Van der Hammen's name is here validated by selecting a fossil grain as type.
Description: Single grain, radially symmetrical, isopolar, spherical. Tricolporate; colpi ectexinous, straight with pointed ends, fairly long; pores indistinct. Endexine < ½ # thick; columellae ½ # long (½-1/z long underneath spines), < ½-# thick; tectate-echinate, tectum < ½ # thick, spines 3-6 # long, 2-4 /z thick at base, sharply pointed, rather densely spaced. Dimensions: 23 # (excl. spines). Variability: A rather large amount of variability is found in size and in degree of spinosity. However, the spines are always separated and not connected by a reticulate pattern of muri. Distribution: In all three areas investigated virtually restricted to the Echitricolporites spinosus Zone. In the Caribbean area scarce occurrences are known, however, from the Crassoretitriletes vanraadshooveni and upper part of the Magnastriatites howardi Zones. Most numerous in the Caribbean Mio-Pliocene sediments, rare in Nigeria, fairly common in Borneo. Taxonomic affinities: This is the tubuliflorae type of the Asteraceae (Compositae). Very similar pollen types are found among the genera Espeletia, Mikania, Pectis, Riencourtia (Plate XVI, 13, 14), Wedelia, and Wulffia and closer identification will prove to be very difficult. Also many extratropical genera of Asteraceae show this pollen type. For a further discussion of its possible origin see the section on "Botanical results". Rev. Palaeobotan.Palynol., 6 (1968) 189-348
335
Echitricolporites meneillyi nov. sp. (Plate XVII, 1; holotype) Derivatio nominis: Named in honour of Mr. D. G. R. Mcneill in recognition of his contribution to Trinidadian palynology. Holotype: Slide TC-165, well CO-73, 333 ft., Trinidad. Description: Single grain, radially symmetrical, isopolar, spherical; outline in polar view trilobate. Tricolporate; colpi ectexinous, fairly long, straight with pointed ends; pores indistinct. Endexine * ½/2 thick; columellae ~--1 /2 high, ¢/2 long (slightly longer underneath spines), . ½ /2 thick; tectate echinate, tectum ½ # thick, spines < 1 /2 long, < ½/2 thick at base, 2-3/2 apart. Dimensions: 23/2. Variability: Slight variability in size and coarseness of sculpture. Comments: The species differs from Echitricolporites eehinatus in its much smaller and more widely spaced spines. Distribution: Only found in the Caribbean area, where it occurs from the base of the Echitricolporites mcneillyi Zone upwards. Taxonomic affinities: This is a small-spined subtype of the tubuliflorae pollen type of the Asteraceae. It is found in the genera Ambrosia (Plate XV[I, 2, 3), Crassocephalum, Ira, and Xanthium. Of these Xanthium forms, with its coarser sculpture, a transition to the larger spirted tubuliflorae type. Ambrosia and lva come very close to the fossil grains. Genus Retitricolporites (VAN DER HAMMEN, 1956) ex VAN DER HAMMEN et WYMSTRA, 1964
Retitricolporites guianensis VAN DER HAMMEN et WYMSTRA, 1964 (Plate XVII, 8, 9)
P L A T E XVII 1. Echitricotporites mcneillyi nov. sp., Trinidad, holotype. 2. Ambrosia cumanensis KUNTH, upper focus, Recent. 3. Ambrosia eumanensis KUNTH, lower focus, Recent.
4. Retitricolporites irregularis VAN DER HAMMENet WVMSTRA,Venezuela, upper focus. 5. Retitricolporites irregularis VAN DER HAMMENet WYMSTRA,Venezuela, lower focus. 6. Amanoa oblongifolia MUELLER-ARG.,upper focus, Recent. 7. Amanoa oblongifolia MUELLER-ARG.,lower focus, Recent. 8. Retitrieolporites guianensis VAN DEn 1-1AMMENet WVMSTRA,Surinam. 9. Retitricolporites guianensis VAN DER HAMMENet WYMSTRA,Surinam. 10. Bombaeaeidites annae (VANDER HAM~E~),Venezuela. 11. Bombax eeiba LINNAEUS,upper focus, Recent. 12. Bombax eeiba LINNAEUS,lower focus, Recent. Magnification × 1,000. 336
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
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Literature: Retitricolporites guianensis VAN DER HAMMENet WYMSTRA,1964, p.235, pl.IH, fig.l-2. Description: Single grain, radially symmetrical, isopolar, prolate. Tricolporate; colpi ectexinous, long and intruding with straight, marginate borders and pointed ends; pores endexinous, circular, 1½-2 # wide, rather indistinct. Endexine ½/z thick; columellae ½/z thick and long, regularly distributed and rather closely spaced; tectum ½ # thick, reticulate; muri ½/~ thick and high, multicolumellhte, but not always distinctly visible, lumina of angular shape, slightly elongated, 3-4/z wide, diminishing in size towards colpi. Dimensions: 28-47/z. Variability: Size and shape of this species are rather variable, the smaller specimens showing a finer ornamentation. The species can, however, be easily recognized by its loose-meshed reticulate sculpture with angular shape of the lumina and thin, low muri. In well preserved specimens the regularly distributed columellae are characteristic. Comments: Inspection of type material has shown the identity of the specimens described here with Retitricolporites guianensis. Our description, however, differs slightly from the one given by VAN DER HAMMEN and WYMSTRA(1964). Distribution: Only known from the Caribbean area where it occurs from the base of the Retitricolporites guianensis Zone upwards. Taxonomic affinities: A certain resemblance exists with pollen of Firrniania colorata and Hildegardia barteri (Sterculiaceae), but a striking difference is the finely reticulate appearance of the fairly broad muff in these types. To a lesser degree this is the difference also with pollen of Glossosternon bruguieri (Sterculiaceae). The pollen of Pterocyrnbiurn beccarii has finely reticulate muri and in addition a thicker wall. Pollen of Sterculia rnexicana has a thicker wall and is finer reticulate on the poles. Trichospermurn pollen (Tiliaceae) has distinctly equatorially elongated pores, although the wall structure is strikingly similar. In view of this situation it is not yet possible to come to a firm decision which taxon has produced Retitricolporites guianensis pollen. However, Sterculiaceae and Tiliaceae are the only families in which this pollen type has been found so far. Retitricolporites irregularis VAN DER HAMMENet WYMSTRA,1964 (Plate XVII, 4, 5) Literature: Retitricolporites irregularis VAN DER HAMMENet WYMSTRA,1964, p.235, pl.III, fig. 9, 10. Description: Single grain, radially symmetrical, isopolar, spherical; outline in polar view circular. Tricolporate; colpi ectexinous, long, strongly intruding with straight costate borders and pointed ends; costae 2/z thick and wide; pores endexinous, oval, 2-3 # wide, equatorially elongated, slightly costate. Endexine 338
Rev. Palaeobotan.Palynol., 6 (1968) 189--348
< 1 # thick, columellae <~ ½/~ thick and long, arranged in a reticulate pattern and supporting in single rows a curvimurate reticulum; lumina of irregular shape, up to 5 / , wide, finer along colpi. Dimensions: 29-50 #. Variability: There is considerable variation in the coarseness of the ornamentation. Occasionally four colpi are present. Distribution: In the Caribbean area present from the base of the Retibrevitricolporites triangulatus Zone upwards. In Nigeria the first scattered occurrences are in the middle part of this zone. Taxonomic affinities: The closest resemblance is with Amanoa oblongifolia (Euphorbiaceae, Plate XVII, 6, 7), less so with Pseudolachnostylis glauca (Euphorbiaceae) which has non-costate apertures and a finer reticulation. Since the former species is, according to LINDEMAN(1953), abundant in scrub wood along creeks on peaty mud in Surinam, it is a likely candidate for producing the fairly large amounts of Retitricolporites irregularis found throughout its range in the Caribbean area. Genus Retibrevitricolpites VAN HOEKEN-KLINKENBERG,1966
Retibrevitricolpites triangulatus VAN HOEKEN-KLINKENBERG,1966 (Plate XVIII, 1, 2)
Literature: Retibrevitricolpites triangulatus VAN HOEKEN-KLINKENBERG, 1966, p.40, pl.II, fig.2. Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view subtriangular. Tricolporate; colpi 4 /* long, ectexinous, marginate, margins 1½ # wide, with thickened tectum; pores endexinous, equatorially elongated and vestibulate, 8/~ long; vestibulum 5 # wide, 1/~ high. Endexine { # thick; columellae 3 # thick and long, slightly longer around pores; tectum ½ # thick, near colpi 1-13 # thick, finely reticulate; lumina 13 # wide, rather angular in shape; perforate on poles; muri ½/~ thick and wide, on poles perforations 3 # wide and 3 # apart. Dimensions: 17-26/~. Variability: Rather pronounced variability in coarseness of sculpture, less so in size and thickness of wall. Comments: The description presented here differs from the original type description presented by the author, but agrees with GONZALEZ'description (1967). Inspection of type material has convinced us that our specimens can and should be incorporated in Brevitricolpites triangulatus VAN HOEKEN-KLINKENBERG.Since pores are present, this genus is here placed in the Class Tricolporatae. Distribution: Both in the Caribbean area and in Nigeria the first occurrence is at the base of the Retibrevitricolpites triangulatus Zone and disappearance at Rev. Palaeobotan. PalynoL, 6 (1968) 189-348
339
the top of the Verrucatosporites usmensis Zone. Absent from Borneo. Taxonomic affinities: Unknown, apparently extinct. Genus Bombacacidites COUPER, 1960 Bombacacidites annae (VAN DER HAMMEN, 1954)
(Plate XVII, 10) Literature: Tricolporites annae VAN DER HAMMEN, 1954, p.96, pl. 9. Retitricolporites (Bombacites) annae VAN DER HAMMEN et
GARCIA, 1966, p.112. Bombacacidites annae LEIDELMEYER, 1966, p.55. Description: Single grain, radially symmetrical, isopolar, oblate; in polar
view rounded-intersubangular. Tricolporate; colpi 14/~ long, ectexinous, slightly protruding, costate; costae 2 # wide; pores indistinct, endexinous, oval, equatorially elongated. Total wall thickness 1~-2/~; endexine ½ # thick; columellae present under muff of reticulum only, ½/z thick and long; tectum reduced to a reticulum; muri multicolumellate, z-17/z ~ 1 thick, ½-1 # high; lumina 1½#-2½/~ wide on poles and near colpi, much smaller on intercolpate areas, where the sculpture is almost perforate; transitions in sculptural distribution are gradual. Dimensions: 49-57 #. Variability: Size and coarseness of ornamentation are variable, but the multicolumellate structure underlying the muff is a fairly constant characteristic, although in badly preserved grains this may have been reduced to a finely granulate pattern. Comments: Our specimens agree with the type material, but in order to differentiate the species from other closely related bombacaceous grains, the recommendation is made to take the multicolumellate structure underlying the muri,
PLATE XVIII Retibrevitricolpites triangulat~s VAN HOEKEr~-KUNKENBERG,Venezuela, upper focus. Retibrevitricolpites triangulatus VAN HOEKEN-KuNKENBERG,Venezuela, lower focus. Margocolporites vanwijhei nov. sp., Venezuela, holotype. Caesalpinia coriaria WILDENOW,upper focus, Recent. Caesalpinia coriaria WILDENOW,lower focus, Recent. Jandufouria seamrogiformis nov. gen., nov. sp., Guyana, holotype. Catostemma altsonii SANDWITH,upper focus, Recent. Catostemma altsonii SANDW1TH,lower focus, Recent, Striasyncolpites zwaardi nov. gen, nov. sp., Trinidad, holotype. 10. Cuphea aequipetala CAVANILLIES,Recent. 11. Perisyncolporites pokornyi nov. gen., nov. sp., Venezuela, holotype. 12. Brachypteris ovata SMALL,Recent. 1. 2. 3. 4. 5. 6. 7. 8. 9.
Magnification x 1,000. 340
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
0
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which is not mentioned by VAN DER HAMMENand GARCIA(1966), as an additional typical feature. Distribution: In the Caribbean area restricted to the Ctenolophonidites lisamae and the Foveotricolpitesperforatus Zones. Absent from Borneo and Nigeria. Taxonomic affinities: Closest resemblance is with certain species of the genus Bombax (Bombacaceae). Especially close are Bombax ceiba (Plate XVII, II, 12), B. rhodognaphalon, and B. pubescens, which all show the multicolumellate structure in varying degrees. Bombax mexicana differs in the pronounced triangular shape. No other genus of Bombacaceae shows this pollen type and identification with a, possibly extinct species of Bombax appears well founded. Genus Margocolporites RAMANUJAM, 1966
Margocolporites vanwijhei nov. sp. (Plate XVIII, 3; holotype) Derivatio nominis: Named in honour of Mr. D. H. van Wijhe in recognition of his contribution to Nigerian palynology. Holotype: Slide TC-166, Venezuela. Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view circular. Tricolporate; colpi ectexinous, 10 # long, costate and surrounded by wide, finely baculate margins with straight edges and pointed ends which are or are not connected at the poles; costae 2 # wide; width of margins in equatorial plane 20/~; pores endexinous, round, 4-5 # in diameter, often slightly protruding. Endexine ½ # thick; columellae 1 # long, ½/~ thick; tectate-reticulate outside colpate margins, muri multicolumellate, 1 # thick and high; lumina 2-2½ # wide at equator, 1-11 # wide on poles. Colpate margins intectate, finely baculate because of densely spaced, evenly distributed columellae. Dimensions: 39-57/~. Variability: Size and coarseness of sculpture are rather variable, syncolporate and colporate grains are included, because in Recent relatives these variations occur within one and the same flower. Distribution: In the Caribbean area occurring approximately from the lower part of the Monoporites annulatus Zone upwards, in Nigeria restricted to the Verrucatosporites usmensis and Magnastriatites howardi Zones, and in Borneo occurring at least from the Magnastriatites howardi Zone upwards, base not yet determined, but absent from the Paleocene and Upper Cretaceous. Taxonomic affinities: Among the Fabaceae (Leguminosae)the following genera show strikingly similar pollen: Adipera, Brasilettia, Caesalpinia, Haematoxylon, Mezoneuron, and Poincianella. Without further detailed studies it is impossible to come to a closer identification of the fossil material. Especially similar, however, is the pollen of Caesalpinia bonduc and C. coriaria (Plate XVIII, 4, 5). 342
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Class Stephanocolporatae [VERSENet TROELSSMITH, 1950 Genus Jandufouria nov. gen.
Derivatio nominis: The genus has been named in honour of Prof. J. Dufour, who successfully stimulated the early palynological investigations in Venezuela. Diagnosis: Oblate, 4-6 colporate, colpi ectexinous, slightly costate, reaching approximately halfway the poles, endexinous pores indistinct, equatorially elongated, wall rather densely columellate, tectate-densely perforate, perforations evenly distributed, lumina < ½/~ in width. Type species: Jandufouria seamrogiformis nov. sp. Comments: This genus accommodates fossil pollen of the Catostemma type. It can be distinguished from Retistephanocolporites by its evenly and densely perforated tectum. Jandufouria seamrogiformis nov. sp. (Plate XVIII. 6; holotype) Derivatio nominis: Name derived from the resemblance in shape to the leaf of the Irish shamrock (Trifolium repens). Holotype: Slide TC-167, well Aurora-l, 651 ft., British Guyana. Description: Single grain, radially symmetrical, isopolar, oblate. 4-6 colporate; colpi ectexinous, 36/z long, reaching half-way the poles, slightly costate with straight borders and pointed ends, costae 1~-2 # wide; endexinous apertures equatorially elongated, faintly costate. Endexine 1 # thick; columellae -~-1 # long, ½ # thick; tectum ½-1 /~ thick, densely and evenly perforated. Dimensions: 40-57/~. Variability: There is some slight variability in size and in wall thickness, but as a rule the species is highly characteristic because of its shape. Distribution: Only known from the Caribbean area, where it occurs from the base of the Verrucatosporites usmensis Zone upwards. Taxonomic affinities: Close resemblance exists with the pollen of the genus Catostemma (Bombacaceae), especially with C. altsonii (Plate XVIII, 7, 8), C. sclerophyllum, and C. fragrans. C. commune has distinctly digitate columellae, a feature which has not been observed in the fossil material so far. The pollen of Aguiaria is similar, but tricolporate. The widespread occurrence of Catostemma in the rain-forests of tropical South America supports the identification.
Class Pericolporatae IVERSENet TROELSSMITH, 1950 Genus Perisyncolporites nov. gen.
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343
Derivatio nominis: Name derived from perisyncolporate apertures. Diagnosis: Spherical, often slightly angular grains. Ectexinous apertures syncolpate, arranged basically in a hexahedral pattern, with variations to higher orders (hepta- to dodecahedr,ql) or lower orders (penta- to tetrahedral) or any incomplete arrangement of the foregoing or absent. Endexinous apertures periporate, in syncolpate grains generally located eccentrically on colpi. Wall thick, tectate. Type species: Perisyncolporites pokornyi nov. sp. Comments: This genus is intended to include the very characteristic fossil malpighiaceous pollen grains listed below. Perisyneolporites pokornyi nov. sp. (Plate XVIII, 11 ; holotype) Derivatio nominis: Named in honour of Mr. G. Pokorny in recognition of his contribution to Colombian palynology. Holotype: Slide TC-168, well OG-1, 5828-5850 ft., Venezuela. Description: Single grain, radially symmetrical, often centro-symmetrical, isopolar, spherical; outline often angular in conformity with aperture pattern. Ectexinous apertures syncolpate, or nearly so, arranged in a complicated pattern, in general according to the ribs of a hexahedron, with variations to higher orders (heptadodecahedral patterns) or lower orders (penta- and tetrahedral patterns) or any incomplete arrangements of the foregoing, deviating in a zonate pattern or totally absent; colpi generally straight or rounded syncolpate, then often very wide and with relatively small intercolpate areas, sometimes very shallow, margins generally slightly costate, costae 1 gLthick, 3 p wide. Pores endexinous, generally circular to oval, 2½-4 t~ wide, if colpi present located eccentrically, frequently less pores than colpi. Endexine 2-3 p thick; columellae < 1 It long, < ½ F~ thick; tectum ½ p thick, slightly thickened along colpi, psilate. Dimensions: 25-47 #. Variability: As discussed above, variation is mainly in aperture number and arrangement. The wall structure is constant, but corrosion often results in a pitted or scabrate surface. Comments: It would be possible, on the base of aperture configurations to split this pollen type into a large number of species, but, since these smaller groups have no restricted ranges, they are united here under one large polymorphic species. Distribution: In the Caribbean area occurring from the base of the Verrucatosporites usmensis Zone upwards, in Nigeria known from the middle part of the Verrucatosporites usmensis Zone upwards. Unknown from Borneo. Taxonomic affinities: This very peculiar pollen type is so far known only from Malpighiaceae. The pollen grains of the following genera correspond best with 344
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
the fossil species: Brachypteris (Plate XVIII, 12), Bunchosia, Hiraea, Mascagnia, Stigmatophyllum, and Tetrapterys. The pollen grains of the Malesian genera of the Malpighiaceae do not belong to this type.
Class Syncolpatae IVERSENet TROELSSMITH,1950 Genus Striasyncolpites nov. gen.
Derivatio nominis: Named after striate ornamentation and syncolpate apertures.
Diagnosis: Oblate, tricolporate; colpi connected at poles, pores protuding; wall thin, finely striate, generally coarser at equator. Type specimen: Striasyncolpites zwaardi nov. sp. Comments: Identical with the pollen type in Cuphea (Lythraceae). Striasyncolpites zwaardi nov. sp. (Plate XVIII, 9; holotype) Derivatio nominis: Named in honour of Mr. A. L. P. Zwaard in recognition of his contribution to Nigerian palynology. Holotype: Slide TC-169, surface sample HO-24, Trinidad. Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view rounded triangular. Tricolpate, colpi ectexinous, connected at poles; pores endexinous, small, protruding over a distance of 2 #. Endexine < ½/z thick; columellae < ½ # thick and long; tectum < ½/z thick, striate in meridional direction; striae ½/z wide, ½/~ apart, coarser at equator. Dimensions: 16-23 #. Variability: Mainly in coarseness of striate sculpture. Distribution: Only known from the Caribbean area, and restricted to the Echitrieolporites spinosus Zone. Taxonomic affinities: This pollen type is only known from the genus Cuphea (Lythraceae). Especially close are C. aequipetala (Plate XVIII, 10), C. pinetorum, C. platycentra, and C. wrightii. ACKNOWLEDGEMENTS In the compilation of this paper the authors were able to draw on the accumulated experience of a large number of colleagues, whose assistance and criticism is gratefully acknowledged here. Thanks are also due to the Management of the Bataafse Internationale Petroleum Maatschappij and the Shell-BP Petroleum Development Company of Nigeria Ltd. for permission to publish this paper,
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345
to Creole Petroleum Corporation and Mene Grande Oil Company (Venezuela) for allowing the publication of well data received in exchange, and to Prof. Dr. C. G. G. J. van Steenis (Leiden) for critically reading the manuscript.
REFERENCES AMERICANCOMMISSIONON STRATIGRAPHICNOMENCLATURE,1961. Code of stratigraphic nomenclature. Bull. Am. Assoc. Petrol. Geologists, 45: 645-665. ANDERSON, R. Y., 1960. Cretaceous-Tertiary palynology, eastern side of the San Juan Basin New Mexico. New Mexico, Bur. Mines Mineral Resources, Mere., 6:58 pp. BELSKY, C. V., BOLTENHAGEN,E. und POTONI~, R., 1965. Sporae digpersae der Oberen Kreide yon Gabun, A.quatoriales Afrika. Paliiontol. Z., 39: 72-83. BOLLI, H. M., 1966. Zonation of Cretaceous to Pliocene marine sediments based on planktonic Foraminifera. Bol. Inform. Asoc. Venezolana Geol. Mineria Petrol., 9: 3-32. BOLTENHAGEN, E., 1967. Spores et pollen du Cr6tacd sup6rieur du Gabon. Pollen Spores, 9(2): 335-355. BRATZEVA, G. M., 1965. Pollen and spores in Maastrichtian deposits of the Far East. Tr. Geol. Inst. Akad. Nauk S.S.S.R., 1 2 9 : 5 4 2 (in Russian). CHRIST, H., 1910. Die Geographic der Fame. Gustav Fischer, Jena, 357 pp. COOKSON,I. C., 1950. Fossil pollen grains of proteaceous type from Tertiary deposits in Australia. Australian J. Sei., Set. B, 3: 166-177. COOKSON,I. C. and PIKE, K. M., 1954. Some dicotyledonous pollen types from Cainozoic deposits in the Australian region. Australian J. Botany, 2: 197-219. COUPER, R. A., 1953. Upper Mesozoic and Cainozoic spores and pollen grains from New Zealand. New Zealand, Dept. Sci. Ind. Res., Geol. Surv. Palaeontol. Bull., 22:77 pp. COVAS, G. y SCHNACK,B., 1945. El valor taxonomico de la relacion "longitud del pistilo: Volumen del grano de polen". Darwiniana, 7: 88-90. CROSS, A. T., 1966. Source and distribution of palynomorphs in bottom sediments, southern part of Gulf of California. Marine Geol., 4(6): 467-524. DRUGG, W. S., 1967. Palynology of the Upper Moreno Formation (Late Cretaceous-Paleocene), Escarpado Canyon, California. Palaeontographica, B, 120: 1-71. ENGLER, A., 1905.15bet floristische Verwandtschaft zwischen den tropischen Afrika und Amerika, sowie iiber die Annahme eines versunkenen brasilianisch-~ithiopischen Continents. Sitz. Ber. Kdnigl. Preuss. Akad. Wiss. Berlin, 1905: 180-231. ERDTMAN, G., 1952. Pollen Morphology and Plant Taxonomy (An Introduction to Palynology, 1). Angiosperms. Almqvist and Wiksell, Stockholm; Chronica Botanica Co., Waltham, Mass., 239 pp. ERDTMAN,G., 1954. On the occurrence of olacaceous pollen grains in Eocene deposits in Germany. Svensk Botan. Tidskr., 48: 804-885. ERDTMAN, G., 1956. Pollen grains of cf. Ctenolophon from Tertiary deposits in India. Grana Palynologiea, 1: 5-7. FucHs, H. P., 1967. Pollen morphology and its relation to taxonomy and phytogeography in the family Bombacaceae. Rev. Palaeobotan. Palynol., 3: 119-132. FUNNEL, B. M., 1964. The Tertiary Period. In: W. B. HARLAND,A. GILBERTSMITH and B. WILCOCK (Editors), The Phanerozoic Time Scale. A Symposium Dedicated to Professor A. Holmes.--Suppl. Qaart. J. Geol. Soc. London, 120: 179-191. GONZALEZ GUZMAN, E., 1967. A Palynological Stud), on the Upper Los Cuervos and Mirador Formations (Lower and Middle Eocene," Tibt~ Area, Colombia). Brill, Leiden, 129 pp. GOTHAN, W. und WEYLAND, H., 1964. Lehrbuch der Paliiobotanik. Akademie Verlag, Berlin, 594 pp. HARRIS, W. K., 1965. Basal Tertiary microfloras from the Princetown area, Victoria, Australia. Palaeontographica, B, 115: 75-106. HOPPING, C. A., 1967. Palynology and the oil industry. Rev. Palaeobotan. Palynol., 2: 23-48.
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HUGHES, N. F. and MOODY-STUART, J., 1966. Descriptions of schizaeaceous spores taken from Early Cretaceous macrofossils. Palaeontology, 9: 274-289. HUTCHINSON, H. and DALZIEL, J. M., 1954. Flora of West Tropical Africa. Crown Agents Overseas Governments and Admini~,trations, London, 2nd ed. revised by R. W. J. KEAY, l(I): 1--294; 1(2): 297-828; 2(1963): 1 544; supplement by A. H. G. ALSTON" Ferns and Fern-Allies of West Tropical Africa, 1-89. JARDINI~, S. et MAGLOIRE, L., 1965. Palynologie et stratigraphie du Cr6tac6 des bassins du S6n6gal et de C6te d'lvoire. MOrn. Bur. Rech. GOol. MiniOres, 32: 187-245. KEDVES, M., 1960. F.tudes palynologiques dans le bassin de Dorog, 1. Pollen Spores, 2:89-118. KEDVES, M., 1961. l~tudes palynologiques dans le bassin de Dorog, 2. Pollen Spores, 3: 101-153. KRUTZSCH, W., 1957. Sporen- und Pollengruppen aus der Oberkreide und dem Terti/ir Mitteleuropas und ihre stratigraphische Verteilung. Z. Angew. Geol., 3: 509-548. KRUTZSCH, W., 1959. Mikropal/iontologische (sporenpal/i.ontologische) Untersuchungen in der Braunkohle des Geiseltales. Geologie (Berlin), Beih., 3 (21-22): 425 pp. KUYL, O. S., MULLER,J. and WATERBOLK,H. T., 1955. The application of palynology to oil geology with reference to western Venezuela. Geol. Mijnbouw, 17: 49-76. LANGENHEIM, J. H., HACKNER, B. L. and BARTLETT, A., 1967. Mangrove pollen at the depositional site of Oligo Miocene amber from Chiapas, Mexico. Harv. Univ. Bot. Mus. Leaflet, 21(10): 289-324. LEIDELMEYER, P., 1966. The Paleocene and Lower Eocene pollen flora of Guyana. Leidse Geol. Mededel., 38: 49-70. LIECHTI, P., 1960. The geology of Sarawak, Brunei and the western part of North Borneo. Bull. Geol. Surv. Dept., Kuching, 3: 1-360. LINDEMAN, J. C., 1953. The Vegetation of the Coastal Region of Suriname. Thesis, State Univ., Utrecht, 135 pp. LOEBUCH, A. R. and TAPPAN, H., 1964. Treatise on Invertebrate Paleontology, part C, Protista-Geol. Soc. Am. Spec. Papers, 1(2): 1 900. MANTEN, A. A., 1966a. Half a century of modern palynology. Earth-Sci. Rev., 2(4): 277-316. MANTEN, A. A., 1966b. Some current trends in palynology. Earth-Sci. Rev., 2(4): 317-343. MAYR, E. (Editor), 1952. The problem of land connections across the South Atlantic with special reference to the Mesozoic. Bull. Am. Museum Nat. Hist., 99, 79-258. MENCHER, F., FlCHTER, H. J., RENZ, H. H. and WALLIS, W. E., 1953. Geology of Venezuela and its oil fields. Bull. Am. Assoc. Petrol. Geologists, 37: 690-777. MILLER, J. B., EDWARDS, K. L., WOLCOTT, P. P., ANISGARD, H. W., MARTIN, R. and ANDEREGG, H., 1958. Habitat of oil in the Maracaibo Basin, Venezuela. In: L. G. WEEKS (Editor), Habitat of Oil. Am. Assoc. Petrol. Geologists, Tulsa, Okla., pp.601-640. M/2LLER, H., 1966. Palynological investigations of Cretaceous sediments in northeastern Brazil. In: J. E. VAN HINTE (Editor), Proceedings of the Second West African Micropaleontological Colloquium, lbadan, 1965. Brill, Leiden, pp. 123-136. MULLER, J., 1959. Palynology of Recent Orinoco delta and shelf sediments. Micropaleontology, 5: 1-32. MULLER, J., 1964. A palynological contribution to the history of the mangrove vegetation in Borneo. In: L. M. CRANWELL (Editor), Ancient Pacific Floras. Univ. Hawaii Press, Honolulu, pp. 3 3 4 2 . MULLER, J., 1966. Montane pollen from the Tertiary of northwestern Borneo. Blumea, 14: 231-235. MULLER, J. and Hou-L1u, S. Y., 1966. Hybrids and chromosomes in the genus Sonneratia (Sonneratiaceae). Bhlmea, 14: 337-343. MULLER, J., 1968. Palynology of the Pedawan and Plateau Sandstone Formations (CretaceousEocene) in Sarawak, Malaysia. Micropaleontology, 14:1-37. NAYAR, B. K., LATA, P. and TIWARI, L. P., 1964. Spore morphology of the ferns of west tropical Africa. Pollen Spores, 6: 545-582. POTONI~, R., 1934. Zur Morphologie der fossilen Pollen und Sporen. Arb. Inst. Paliiobotan. Petrog. Brennstein., 4: 5-24. POTONI~, R., 1956-1960. Synopsis der Gattungen der Sporae dispersae, 1-3. Geol. Jahrb. Beih., 23(1956): 1 103; 31(1958): 1-114; 39(1960): 1 189.
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POTONI~, R. und GELLETICH, J., 1933. Lrber Pteridophyten-Sporen einer eoc/inen Braunkohle aus Dorog in Ungarn. Sitz. Ber. Ges. Naturforsch. Freunde Berlin, 1932: 517-528. RAMANUJAM, C. G. K., 1966. Palynology of the Miocene lignite from south Arcot district, Madras, India. Pollen Spores, 8: 149-203. REYMENT, R. A., 1965. Aspects of the Geology of Nigeria. Univ. Press, Ibadan, 144 pp. SAAD, S. I., 1962. Pollen morphology of Ctenolophon. Botan. Natiser Lunds Botan. Fdren., 115(1): 49-57. SCHAUB, H. P., 1948. Outline of sedimentation in Maracaibo Basin, Venezuela. Ball. Am. Assoc. Petrol. Geologists, 32: 215-227. SCHWARCK ANGLADE,A. (Editor), 1956. Lexico Estratigrafico de Venezuela. Bol. Geol., Publ. Especial., Mitt. Minas e Hidrocarbon, l : 740 pp. SHORT, K. C. and STXUBLE, A. J., 1967. Outline of geology of Niger delta. Bull. Am. Assoc. Petrol. Geologists, 51: 761-779. SIMPSON, G. G., 1952. Probabilities of dispersal in geologic time. In: E. MAYR (Editor), The Problem of Land Connections across the South Atlantic with Special Reference to the Mesozoic--Bull. Am. Museum Nat. Hist., 99: 163-176. STOLK, J., 1963. Contribution h l'6tude des correlations microfauniques du Tertiaire inf6rieur de la Nigeria m6ridionale. Dans: Colloque International de Micropalkontologie, Dakar--Bur. Rech. G~ol. Minikres Mdm., 32:247 275. TRALAU,H., 1964. The Genus Nypa VAN WURMB. Kgl. Svenska Vetenskap. Akad. Hand/., 10(1): 1-29.
VAN GIJZEL, P., 1961. Autofluorescence and age of some fossil pollen and spores. Konh~kl. Ned. Akad. Wetenschap., Proc., Ser. B, 64: 56-63. VAN DER HAMMEN, T., 1954. El desarrollo de la flora Colombiana en los periodos geologicos, 1. Maastrichtiano hasta Terciario mRs inferior. Bol. Geol. (Bogota), 2(1): 49 106. VAN DER HAMMEN, T., 1956a. Nomenclatura palinologica sistematica. Bol. Geol. (Bogota), 4: 23-62. VAN DER HAMMEN, Y., 1956b. A palynological systematic nomenclature. Bol. Geol. (Bogota), 4(2]3): 63-101. VAN OER HAMMEN, T., 1956c. Descripcion de algunos generos y especies de polen y esporas fosiles. Bol. Geol. (Bogota), 4: 103-109. VAN DER HAMMEN, T., 1956d. Description of some genera and species of fossil pollen and spores. Bol. Geol. (Bogota), 4(2/3): 111- l 17. VAN DER HAMMEN, T. and GARCIA DE MUTIS, C., 1966. The Paleocene pollen flora of Colombia. Leidse Geol. Mededel., 35:105-116. VAN DER HAMMEN, T. and WVMSTRA, T. A., 1964. A palynological study of the Tertiary and Upper Cretaceous of British Guiana. Leidse Geol. Mededel., 30:183 241. VAN HOEKEN-KLINKENBERG, P. M. J., 1964. A palynological investigation of some Upper Cretaceous sediments in Nigeria. Pollen Spores, 6: 209-231. VAN HOEKEN-KLINKENBERG,P. M. J., 1966. Maastrichtian, Paleocene and Eocene pollen and spores from Nigeria. Leidse Geol. Mededel., 38: 37~8. VAN RAADSHOOVEN, B., 1951. On some Paleocene and Eocene larger Foraminifera of western Venezuela. World Petrol. Congr., Proc., 3rd, The Hague, 1951, Sect. I, pp.476~89. VAN STEENIS, C. G. G. J., 1962a. The distribution of the mangrove genera and their palaeogeographical implication. Koninkl. Ned. Akad. Wetenschap., Proc., Ser. C, 65: 164-169. VAN STEENIS, C. G. G. J., 1962b. The land-bridge theory in botany. Blumea, 11(2): 235-372. VARMA,C. P. and RAWAT,M. S., 1963. A note on some diporate grains recovered from Tertiary horizons of India and their potential marker value. Grana Palynologiea, 4:130-139. W1LSON, J. T., 1965. Evidence from ocean islands suggesting movements in the earth. In: P. M. S. BLACKETT, E. BULLARDand S. K. RUNCORN (Editors), A Symposium on Continental Drift-Phil. Trans. Roy. Soc. London, Ser. B, 1088: 145-167. WYMSTRA, T. A., 1967. A pollen diagram from the Upper Holocene of the Lower Magdalena valley. Leidse Geol. Mededel., 39: 261-267. WYMSTRA,T. A. and VAN DER HAMMEN,T., 1967. Palynological data on the history of tropical savannas in northern South America. Leidse Geol. Mededel., 38:71-90.
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P A L Y N O L O G Y OF TERTIARY SEDIMENTS FROM TROPICAL AREAS J. H. G E R M E R A A D , C. A. HOPPING ANI~ J. MULLER ~
Bataafse Internationale Petroleum Maatschappij, The Hag,e (The Netherlands) (Received February 8, 1968)
SUMMARY
This article deals with the most important aspects of nearly twenty years of intensive study of the pollen-and-spore content of Tertiary sediments in some parts of tropical South America, Africa and Asia. For a proper evaluation, the character of the data, including the selection and preparation of the samples, the diversity of previous recording and the statistically achieved uniformity in presentation of these basic data needs a full exposition, given in the introduction. This is directly followed by an explanation of the process of elimination of all stratigraphically unimportant species. The resulting interpretation of climatic and topographical influences on the dispersal of pollen and spores is illustrated with examples from the fossil record. The disturbing effect of redeposition forms a problem, which in some cases can be solved. Now that the main ways of dispersal of pollen and spores are understood, the characteristics of the three major depositional environments can be distinguished by purely statistical analysis, without necessarily having any botanical information from probably related Recent plant species. Additionally botany and palaeontology may bring supporting evidence. This many-sided approach leads to the discrimination between local and regional features of environmental or timestratigraphical significance which is needed for the evaluation of long-distance correlation. As a result the marker species can be classified into: (1) a restricted number of pantropical marker species; (2) a larger number of marker species which occurred in both the South American and west African regions, tropical today (transatlantic distribution); and (3) a still greater quantity of species which are of significance only within a single botanical province (intracontinental distribution). Thus a broad stratigraphical framework on a pantropical scale is established, which may be further subdivided regionally. These three systems of subzonation are compared with independent zoopalaeontological time-stratigraphical correlation and discussed in great detail, with special emphasis on the Carribean data. 1 Present address: Rijksherbarium, State University, Leiden (The Netherlands).
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
189
The major palynological changes marking the boundaries of the pantropical subzonation are thought to reflect the evolution of new groups of plants. They are mostly marked by a gradual incoming of pollen types. Extinction of plants is stratigraphically of less value, since they may have survived longer in one area than in another. Climatic boundaries are next in importance, but in general they are more restricted to specific regions. Similarly the immigration of plants, although producing sharp and useful boundaries, is only of regional value. Of least significance for regional correlation are the locally restricted boundaries which are caused by changes in habitat or dispersal. They may still be valuable for studies within one basin. An intriguing aspect of the palynological studies is formed by the possible affinity of the fossil type with Recent botanical species. Such affinities are obviously present in many fossil types. Whereas most are restricted to the level of family relationship, some interesting cases of much closer affinity are recorded here. In exceptional cases the morphogenetic development and migration of a restricted group of related pollen types can be traced. In the final section of this paper the species selected for this study have been formally described and illustrated; they include several new ones. The study is further documented by distribution charts and sections showing the stratigraphical significance of the marker types, as discussed in detail in the stratigraphical section.
INTRODUCTION
This paper presents some of the results obtained in twenty years of palynological investigation of Tertiary sediments from tropical areas by companies of the Royal Dutch/Shell Group. The primary purpose of this investigation was to arrive at a better interpretation of the stratigraphy of those Tertiary sedimentary basins where other means of correlation failed. Of course it is not possible in this paper to do more than present an outline of the large amount of work done and to select for discussion a few topics which appear to be of more general interest. Documentation will also be restricted to selected examples.
MATERIALS AND METHODS
The restriction of the subject of this paper to the Tertiary of tropical areas is due to a combination of factors. Firstly, the tropics represent a natural geobotanical unit. Secondly, palynological research by Shell was initially mainly concerned with the Tertiary sediments of northern South America, Nigeria and Borneo. Thirdly, the amount of detailed information on the Upper Cretaceous palynolo190
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
gical succession in these areas is still very scanty and the base of the Tertiary represents, therefore, at the present state of knowledge, a logical lower limit. Pleistocene strata have been studied too, but Holocene sediments have been left out of consideration because of lack of information. Geographically the main emphasis will be put on the South American data, which are by far the most extensive, covering Colombia, Venezuela, Trinidad and the Guianas. From Africa only the Nigerian Tertiary succession is adequately known. In the Far East, Borneo has supplied valuable information, but here the stratigraphical coverage is incomplete, data on the Eocene being very limited. The number of samples on which the study is based, is very large. Only samples collected at the surface and cores and sidewall samples taken in wells have been studied. As far as possible sections were chosen which contained, or were situated in close proximity to, samples dated by other means. Tropical Tertiary pollen floras are very rich in species and the average type collection may easily contain 800-1,000 different species. For stratigraphical purposes generally less than 200 are of importance per area. For a comprehensive review, such as this, a further reduction is desirable and only 49 species are discussed. These are, firstly, the species used to establish the major zonation, and some which are of importance for elucidating local correlation problems. In addition a few species of intrinsic botanical interest are discussed. Fossil species have as far as possible been referred to published ones 1. The introduction of new names has thus been kept to a minimum. Preparation of samples was mainly by standard techniques, modified according to local needs. For Neogene material treatment with HF, followed by bromoform separation, is generally sufficient, although when much plant debris is still present acetolysis may be helpful. For Palaeogene sediments slight oxidation with Schulze's mixture may be advantageous. The majority of the sediments examined consisted of clay and shale, silt or siltstone with varying amounts of carbonaceous material. Sandy sediments or coals were generally avoided. The basic data are presented on distribution charts accompanied by all pertinent lithostratigraphical and additional palaeontological information (Fig.l14). Again it must be emphasized that only examples are given. A complete documentation would have been impossible because of lack of space. However, the range chart (Fig.15) presents a compilation of all the data assembled for this study. Unfortunately, when palynological work was started in the different areas, no uniform system of recording data was adopted. Sometimes percentages were 1 In this connection we should like to express our gratitude for the facilities extended to us by Dr. T. van der H a m m e n (Amsterdam) and his staff, which enabled us to study the type collections not only of already described species but also of types to be described in future publications.
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
191
calculated on the basis of a pollen sum; in other cases a rough estimate of the abundance of the species was given. In order to create uniformity in the presentation of these quantitative data on our distribution charts, the occurrences are expressed as a value for the probability of re-observation, i.e., if a specified number of additional specimens from a new sample of the same rock or stratum were to be investigated. This re-observation of the species may be in any number of specimens (grains), including one only. This chance of re-observation is computed according to the following formula: a
P=I--(1--
M
N )
where a : the amount, that is the number of grains of the single species observed in the old sample; N : the sum of the amounts of all species, that is the total number of grains or pollen sum observed in the old sample; M : the sum of the amounts of all species in the new sample. Depending on the accuracy required by the palynological investigation and the time and sample material available, the value of M may be taken larger or smaller than 100. For technical reasons related to the type of computer at present in use for palynological data processing, the value of M is here taken to be 88. This conforms approximately to the current sample size of 70-I00 specimens of the selected species. The advantage of such a relatively small sample size lies mainly in the possibility of examining large numbers of samples within a short time, which is essential for routine work, both stratigraphically and statistically, and is far more informative than a few samples with large pollen sums. In general the counting of the marker species takes place in two phases. First, an analysis is made of the whole flora in which the dominant species like Rhizophora are also counted. The second part of the microscopical investigation is concerned only with the more rare but important markers, among which, e.g. Asteraceae (Compositae). To save time dominant species are no longer counted, but statistically it is not permissible to multiply the amount counted to get the corresponding figure. Therefore, the probability of re-observation of, for instance, Rhizophora pollen is calculated from the first pollen sum, but the probability of re-observation of the rare markers like Echitricolporites spinosus from the second pollen sum. Example." I - - c o u n t o f t h e w h o l e f l o r a , i n c l u d i n g , i n t e r alia, Rhizophora -- 100 g r a i n s . c o u n t o f t h e s p e c i a l s e l e c t i o n , e x c l u d i n g Rhizophora : 84 g r a i n s . A m o u n t o f Rhizophora in ' T ' : 8 0 g r a i n s , p r o b a b i l i t y o f r e - o b s e r v a t i o n = ! - - (1 - 8 0 / 1 0 0 ) ss : 1.00. A m o u n t o f Echitricolporites sphwsus in " I " = l g r a i n , p r o b a b i l i t y o f r e - o b s e r v a t i o n = 1 - - (I - - 1/100) ss == 0 . 5 9 0 . A m o u n t o f Echitricolporites spinosus in " l I " = 4 g r a i n s , p r o b a b i l i t y o f r e - o b s e r v a t i o n = 1 - - ( I - - 4 / 8 4 ) ss = 0 . 9 8 6 . II :
192
Rev. Palaeobotan. Palynol.,
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of re-observation of this species in I is of little interest and is not recorded on the distribution charts presented. This example also shows the importance of further counting of the selected species. In order to avoid the impression of high accuracy and to facilitate visual evaluation of the charts, the probability values on the distribution charts (Fig.l-14) were grouped into classes and each class was indicated in the following way: P 0.01-0.75 -- . P 0.75-0.90 = / P 0.90-0.95 = o P 0.95-0.99 = P 0.99-1.00 = • An interrupted vertical line on some distribution charts indicates a distribution of a species which was not counted but which appeared common to abundant in most samples of the interval examined.
INTERPRETATION OF' DATA
The practical purpose of our investigations can be briefly stated as the establishment of a time-stratigraphical zonation, adapted to the scale of the geological problem under investigation. To achieve this goal a discrimination between stratigraphically reliable and unreliable pollen and spore types is necessary. The problems may vary from detailed correlation between wells a few kilometres apart in order to solve, for instance, tectonical complications, to broad correlation between sediments of widely differing facies hundreds or thousands of kilometres apart in different basins of deposition. It is of special importance to evaluate, for every part of the zonation, the scale on which it is valid, together with an estimate of the degree of accuracy. The selection of the 49 species discussed and the zonation established in this paper were preceded by a detailed study of the factors which influenced the regional significance of these markers. It is of course impossible to present a full account of this elimination process. Instead an attempt will be made in this section of the present paper to outline the principles involved with the aid of a few concrete examples. First the factors influencing the composition of the pollen record in the rocks will be analysed. Then the data from other disciplines, viz. botany, geology and zoopalaeontology, which permit a better understanding of microfloral changes, will be discussed, leading finally to the establishment of a zonation. The pollen spectrum, obtained by calculating the percentages in which the various species occur in a sample, is the end result of various factors which influence production and dispersal. Rev. Palaeobotan. Palynol., 6 (1968) 189 348
203
Primary factors control the presence of the plants which produced the pollen grains and spores, and secondary factors affect dispersal prior to fossilization.
Evohttionary change and migration Primary factors are evolutionary change and migration or increases and decreases in response to changes in climate or topography. Evolutionary change may obviously be expected to yield the most reliable criteria for the establishment of a time-stratigraphical framework of regional significance. Examples are the gradual development of Poaceae (Gramineae) and Asteraceae (Compositae), as reflected in the stratigraphical distribution of the corresponding pollen types. Since these are large and varied groups of plants with at present a virtually world-wide distribution, their first appearance and subsequent development have proved to be of wide time-stratigraphical significance. An example of evolutionary development on a subregional scale is the evolution of Sonneratia pollen types in the Indo-Malesian area. As will be discussed in detail later, it was possible here to trace morphogenetic changes within a single lineage. However, such cases are exceptional, and pollen and spore species generally appear fairly suddenly in the stratigraphical record without any indication of their phylogenetic origin. Unless coinciding with a hiatus in the stratigraphy, these relatively sudden appearances must have been caused by changes in the environment which enabled the parent plants involved to increase in numbers and extend their geographical range. The main factor of interest here is climatological. The problem of how to recognize the effect of changes in climate in the stratigraphical distribution patterns of the many species studied can be approached in a direct way by botanical identification of fossil pollen and spore types with living taxa, which have well-defined climatological tolerances. So far not much success has been achieved in this direction, since none of the identified lowland species discussed in this paper are known to be indicative of a specific climate except in so far as they are adapted to the tropical climate in general. However, it is sometimes possible, by reference to climatologically significant lithological changes, to detect the relative climatic requirements of certain fossil markers. Such a case was present in the Oligo-Miocene (Magnastriatites howardi Zone) of western Venezuela. Here a local accumulation of anhydrite in shales, contrasting strongly with coal-bearing underlying strata, was associated with a peculiar pollen flora not encountered elsewhere inthiscomposition. Here the inference of a climatological change towards greater aridity was possible. Another case in which a climatological cause may be detected is the rather sudden disappearance of certain pollen species. The extinction of Nypa-type pollen at the Eo-Oligocene boundary in Venezuela is approximately contemporaneous with a widespread increase in the incidence of mottled shales, indicating a change 204
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
to a climate with more pronounced seasonal rainfall. It is conceivable that such a change could have caused Nypa to disappear, since the plant at present is mainly restricted to the ever wet tropics in the Indo-Malesian area. The often rather sudden immigration of certain species may also have been caused by a change in climate which enabled the plants involved to extend their range. An example which could be explained this way is the rather sudden appearance in the Eocene of western Venezuela of Retitricolporites guianensis and Cicatricosisporites dorogensis. However, such phenomena may also be due to the development of new pathways of migration. A good example of this is the southward migration along mountain chains of montane elements such as Alnus. In Borneo this could be attributed to a mid-Tertiary phase of mountain building. In the Caribbean area the cooling of the climate at the beginning of the Pleistocene must have facilitated the migration of Alnus along existing mountain chains from the north. An analogous case is the dispersal across oceans of plants which are adapted to a coastal environment, such as mangroves. If such floral changes are considered for the definition of a regional zonation, the question of dispersal speed must be taken into account. Although little is known quantitatively from Recent plants, it must be assumed that differences in this respect exist and that they depend on factors such as adaptation and viability of the seeds. The conspicuously sudden appearance and subsequent rapid increase of Asteraceae (Compositae) pollen types in the Lower Miocene of northern South America, Nigeria and the Far East could reflect the adaptation to easy dispersal of Asteraceae seeds. In contrast one distinct case of delayed dispersal has come to light: Symphonia pollen appears earlier in the stratigraphical record in Africa than in South America and this obviously is a consequence of the difficulty of crossing the Atlantic Ocean. It will be clear that such cases can only be detected when independent dating is available, and they should of course not be utilized for the definition of a regional time-stratigraphical zonation. The majority of the floral changes observed on the distribution charts will, however, have been influenced to a varying degree by local facies factors. For instance, the varying abundance in which mangrove pollen occurs in the sedimentary record, once it has made its first appearance in the area, largely reflects the acreage covered by mangrove, which is determined by the local topography. It will now be clear that, if climatological and topographical influences are of restricted lateral extent, the interplay of the environmental conditions on the one hand, and the variable tolerances of different species on the other, combine to produce complicated stratigraphical distribution patterns in which time-stratigraphical correlation lines are not easily detected. Rev. Palaeobotan. Palynol., 6 (1968) 189-348
205
Dispersal of pollen grains and spores In addition, the secondary factors controlling pollen and spore dispersal may further obscure the patterns. The majority of the samples investigated are deltaic-marine silts, clays and shales, which means that the individual grains were generally transported, mixed, sorted according to size and possibly redeposited once or several times. Before giving a few examples of such complicated patterns, it is necessary to discuss the influence of the secondary factors in greater detail. Relatively soon after starting the investigation of Tertiary clastic sediments in the tropics, it was realized that the conventional picture of a fairly homogeneous pollen rain, failing impartially in various sedimentary environments, was inadequate for an understanding of the complicated stratigraphical distribution patterns encountered. Studies of Recent tropical sediments have since shown that, in a humid environment at least, water transport may be of far greater quantitative importance than wind transport (MULLER, 1959). In the dispersal picture which has now evolved all species pass initially through a phase of air transport. This phase may be of very short duration as, for instance, in tropical peat swamp forests, where most of the pollen produced by the trees was found to be deposited within a very restricted area. If the peat formed here is preserved in the geological record as coal, no further transport takes place, except when lumps of coal are later eroded and transported as pebbles. At the other end of the scale, the pollen grains and spores produced by the montane vegetation in the tropics are known to be transported in large quantities over considerable distances by high-altitude atmospheric currents. This is especially true of wind-pollinated trees such as Alnus, Pinus, and of certain ferns. Sooner or later, however, mainly depending on wind strength, turbulence and wash-out by raindrops, all pollen grains and spores land on the earth's surface. If they are not soon carried away by water, they are mostly destroyed by corrosion and escape fossilization. A different fate, of course, awaits that portion of the pollen rain which is caught in river systems or the sea. It makes a great difference whether further transport takes place by river systems or whether pollen grains and spores settle directly on the surface of the sea with further transport exclusively by sea currents. In the first case, a small proportion of the pollen gathered from the entire drainage area will be deposited in the alluvial and coastal plain sediments in the delta area, but most of it will be concentrated at the river mouth and discharged together with the sedimentary load into the sea. In this way concentrations of pollen in fluviomarine sediments close to river mouths are formed, such as have been found in front of the Orinoco delta (MULLER, 1959) and in the Gulf of California (CRoss, 1966). Size sorting will hardly be noticeable during this phase and tidal currents and turbulence will generally cause efficient mixing of the final 206
Rev. Palaeobotan. Palynol., 6 (1968) 189-248
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pollen suspension entering the sea. Also, the largest number of species will be present in the fluviomarine sediments. In the second case the composition of the pollen load is quite differently affected. First of all sea currents act as slow transporting agents over wide fronts with relatively less turbulence further offshore; the result is gradual settling and deposition of pollen grains and spores, accompanied by size sorting. Wind-transported pollen may be added and this may considerably modify the composition of the pollen load in areas far offshore. Another factor about which little is known is selective corrosion of pollen and spores during seaborne transport. One final complication has to be evaluated and this is the probability that not all pollen is travelling in a single move from anther to final resting place, but that temporary entrapment in sediments is followed by subsequent erosion and that renewed transport takes place. This recycling of pollen grains and spores may take place within what is geologically speaking an insignificant period of time, as is the case in the average delta, where meandering streams may erode sediments deposited only a short while before. Such recycling, of course, only increases the degree of mixing of the pollen load eventually supplied to the sea and does not affect stratigraphical distribution patterns to any appreciable degree. However, when the time lag between deposition and recycling becomes greater, serious difficulties may arise, culminating when older pollen-bearing formations are eroded in the source area of a river system. When a clear difference in preservation between such older reworked pollen grains and spores and autochthonous ones is present, they can be easily excluded from the pollen sum, but unfortunately this is usually the exception rather than the rule. Generally there is no clear-cut difference, and the presence of many slightly different corrosion patterns in one single sample may be the only clue indicating the presence of several generations of reworked pollen grains and spores. In such cases a detailed knowledge of the basic floral succession in the area of investigation may enable one to spot the scattered presence of anomalous pollen associations and to recognize them as reworked assemblages. Here general geological considerations, indicating the probable origin of the sediment particles have also to be taken into account. Recently VAN GIJZEL (1961) has demonstrated that fluorescence microscopy may be able to discriminate between autochthonous and reworked pollen. In the Palaeogene sediments of western Venezuela, for instance, reworked pollen was scarce because the bulk of the sediments deposited during that time had been derived from the Guiana shield, where no pollen-bearing sediments were eroded. In younger sediments the occurrence of reworked pollen of a Palaeogene age proved to be clearly related to distinct unconformities. In contrast, in the Neogene sediments of northwestern Borneo no such clear-cut unconformities exist and since the sediments had been recycled many times during the course of the Tertiary, a rather diffuse distribution of reworked Rev. Palaeobotan. Palynol., 6 (1968) 189-348
221
pollen was the result. It was not unusual to recognize in a single sample up to three different generations of reworked pollen and spores, which created considerable difficulties in the interpretation. This situation has practical consequences for the establishment o f a zonation, since the oldest occurrence of species obviously is more reliable than the youngest. In fact the regional zonation presented here is exclusively based on such oldest occurrences. However, when cuttings have to be investigated for routine purposes, the youngest occurrences may be of greater practical value.
Examples The practical application of the above principles will now be illustrated with a few examples. The first case refers to base Monoporites annulatus Zone in northern South America. Within the Eocene of western Venezuela, which was the first area investigated, two floral boundaries were apparent in approximately the same stratigraphical interval: aal well-defined increase in Echitriporites trianguliJormis and, slightly higher, a less conspicuous base of Monoporites annulatus. Later the absence ofEchitriporites trianguliformis in the Eocene of Colombia was noted. This absence could not be attributed to a stratigraphical hiatus or to a different climate, since the remainder of the floral assemblage proved to be essentially similar. However, the Colombian Eocene sediments are more terrestrial than those in Venezuela, and it became clear that Echitriporites trianguliformis was derived from a coastal plant with mainly waterborne dispersal of its pollen in seaward direction. This reduced its value for regional correlation and, since Monoporites annulatus appeared to have a wider distribution, because it was derived from a more inland environment, its increase in the Early Eocene both in marine and more terrestrial deposits is preferred as the regionally valid time-stratigraphical correlative horizon. The marked increase in Echitriporites trianguliformis retains, however, its practical correlative value within the restricted area of the Lower Eocene in the Maracaibo basin. In the case of the top in the occurrence of Proteacidites dehaani (Upper Cretaceous) it was soon apparent that this event could be recognized both in marine deposits in the northern Maracaibo basin and in alluvial plain deposits in Colombia and the southern Maracaibo basin. Regional time-stratigraphical value could, therefore, be assumed for this floral boundary. In both these examples botanical identification of the pollen species was impossible or did not provide sufficient evidence to permit an independent check on the environmental requirements of the parent plants. The method outlined above was the only feasible one for the recognition of time-stratigraphical value. In the examples from the Neogene, described below, on the other hand, this sort of conclusion is indeed supported by direct botanical evidence. 222
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
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In the Oligo-Miocene the first increase in the Rhizophora pollen type (Zonocostites ramonae) can only be reliably observed in coastal and offshore marine sediments, while the approximately contemporaneous first increase in the Ceratopteris type (Magnastriatites howardi) can be detected in terrestrial environments as well. However, the small fresh-water ferns of the genus Ceratopteris can only flourish in open vegetation and will hardly occur under a closed forest canopy, which restricts the dispersal of the spores to water transport mainly. Ceratopteristype spores thus occur more regularly in inland environments, where Rhizophora pollen can be extremely rare, and therefore their oldest occurrence has been taken as the more reliable time-stratigraphical horizon. In practice of course both floral changes support each other and are used in conjunction. Another example from the Neogene of western Venezuela concerns the recognition within the same body of strata of three sets of correlation lines: (1) A topographically-influenced succession of mangrove dominance alternating with more inland vegetation. (2) A subregional succession, probably of a climatological nature. (3) A top occurrence of Cicatricosisporites dorogensis. The correlation lines derived from (1) cross at an angle those from (2), while none of these were observed in the adjoining fully marine succession. However, the top occurrence of Cicatricosisporites dorogensis proved to be recognizable regardless of environmental influence, and thus was judged to be of major timestratigraphical significance. In general the principle may be formulated that any palynological change which is paralleled by a facies change is of questionable time-stratigraphical value. if, on the other hand, the pattern of palynological changes crosses the environmental correlation lines derived from lithology or benthonic faunal distribution, then that pattern is likely to be of time-stratigraphical value at least within the area of study.
Statistical analysis of the palynological data In the absence of positive information from lithology, faunal or botanical affinities or climatic indications, statistical analysis of the palynological data can be developed into a powerful tool for interpretation. A first method is to measure the percentage variation, which is high in a terrestrial environment where pollen dispersal is restricted and low in a marine environment in which the pollen load has become thoroughly mixed. This variation is best measured by calculation of the standard deviation, for which a minimum of twenty samples is necessary. This calculation is, however, applicable only to common species. Secondly, an attempt can be made to separate statistically associations of species which have a common source area. For instance, if alluvial-plain deposits
Rev. Palaeobotan.Palynol., 6 (1968) 189-348
233
are being investigated, the percentages of the species inhabiting this environment will vary greatly, depending on the local edaphic factors, while species associations from outside this environment and transported into it in a better-mixed composition will always show a constant ratio. If successful, such a statistical analysis will enable the palynologist to separate, for instance, mangrove, river bank, peat swamp, alluvial swamps and marshes, upland and montane associations. The proportion in which these associations occur will then be mainly a function of the general topography of the source area as a whole, while any changes occurring within associations may have climatic or evolutionary significance and will be of greater time-stratigraphical significance. Association tests can be adapted for this approach. Thirdly, the variation in occurrence between rarer types is best measured with a run length test, which measures the variation in distance and length of series of single occurrences. To be reliable a minimum of 80 consecutive samples are needed for this test, which can also be applied to more common species when a minimum percentage truncation is chosen. All these statistical tests can be so devised that the significance of the results is expressed in probability values. One disturbing factor may be the presence of reworked pollen as erratic assemblages. For large numbers of samples, calculation by means of mechanical data processing is, of course, the only practical method of applying these statistical tests.
Summary of interpretation experience Summarizing twenty years of experience, it may be stated that for most cases tools are available which allow discrimination between local and regional events of time-stratigraphical value on the one hand and effects caused by time-crossing events such as transgressions and regressions on the other. This information then allows the establishment of a zonation adapted to the particular stratigraphical problem at hand. For short distances and short time intervals the effects of striking topographical events may provide the correlative framework; for correlation over larger distances climatological changes will produce the best means, while on an intercontinental scale correlation on evolutionary change appears to be the only reliable method. In general, however, the larger the distance, the more difficult it becomes to define and trace sharp floral boundaries. In particular boundaries defined on evolutionary change are notoriously hard to place accurately in thick continuouslydeposited sediments. This often poses a practical problem, since the geologist generally requires correlation lines, while the palynological events on which the zonation is based are by nature mostly gradual. In fact any sharp floristic boundary is more probably indicative of a hidden unconformity than of anything else. 234
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
It is worth ending this chapter by listing below a few more of the limitations encountered in applying palynological correlation methods. (1) Determinable pollen and spores absent or scarce. This may be due to: (a) original scarcity in sediments such as sands, conglomerates, limestones; (b) destruction by oxidation shortly after deposition, e.g., mottled clays; (c) destruction by oxidation after weathering of outcrops, common in the more arid parts of the tropics; (d) destruction due to high temperature effects caused by deep burial, volcanic activity, proximity of intrusions, heat generated by tectonic friction. (2) Statistical errors. These fall mainly under two headings: (a) the use of inadequate counts; (b) the use of an unsuitable selection of species which comprises the pollen sum, if percentage ratios are calculated. As regards (2a) the main practical problem is to achieve a maximum of results with a minimum count. In practice a count of 70-100 selected marker species with a sampling distance of 75-100 ft. has proved to be entirely adequate for the solution of most correlation problems. Here, the number of grains counted per sample has been sacrificed to the number of samples investigated. If more than one investigator is counting the same material, the influence of determination and counting errors should be eliminated by carefully designed counting schemes, which will average out individual errors. Errors grouped under (2b) are bound to influence the results especially when floral changes are indistinct, as in the case of thick sedimentary series deposited within a short interval of time, or when local influences in the pollen spectra obscure the occurrence of scarce regional marker species. Then it becomes imperative to test various percentage sums in order to arrive finally at the combination of species which, in their changing ratios, will reflect most distinctly the events of time-stratigraphical value on which the correlation will be based. This is an important point and it should be clearly understood that the percentage calculation system employed in the present study is adapted to the recognition of the zones described here. Other studies, for instance of a localized area in a restricted interval only, will start with a different pollen sum. In every area one of the principal problems in the early phase of developing a zonation in the extremely rich tropical Tertiary microfloras has been to decide which marker species to include in the pollen sum. Generally the marker species have been divided into two groups. Group A comprises all species which are of importance for the major regional zones, while group B contains those types whose fluctuations are of more local significance. Again one of the advantages of mechanical data processing is that this allows the rapid calculation, plotting and comparison of percentages based on different pollen sums.
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
235
ZONATION
The zones recognized in this paper are biostratigraphical units in the sense of the AMERICAN COMMISSION ON STRATIGRAPHIC NOMENCLATURE (1961). They are, therefore, not a priori to be considered as time-stratigraphical units and in fact some of the boundaries delimiting the zones probably are not contemporaneous over large distances. However, within the areas in which the zones are recognized, their succession is identical in all sections investigated. According to their lateral extent, the zones are grouped as follows: (1) pantropical zones; (2) transatlantic zones; (3) intracontinental zones. The definition and description of the zones will be documented by a restricted number of type sections, mainly taken from northern South America (Fig.l-14). The range chart (Fig.15) illustrates the ranges of all species discussed, based on evidence from a much larger number of sections. The independent dating of the zones is discussed in the section "Independent dating".
Pantropical zones The oldest pantropical zone recognized is the Proxapertites operculatus Zone characterized by the regular co-occurrence of Proxapertites operculatus, Proxapertites cursus, the Spinizonocolpites echinatus group, and Eehitriporites trianguliformis. Its base, which as yet could only be studied in Nigeria and Borneo, is provisionally defined by the qualitative base of the occurrences of Echitriporites trianguliformis and the Spinizonocolpites echinatus group. Further study is necessary to define and evaluate more accurately the base, which is probably of Senonian age. The zone is well-developed in the Rubio-road section (Venezuela) (Fig.3), well Egoli-1 (Nigeria) (Fig.9), and in the Lundu-Kayan section (Borneo) (MULLER, 1968). The transition to the overlying Monoporites annulatus Zone is marked by the first regular occurrence of Monoporites annulatus. This is not a sharply defined event, since the increase in Monoporites annulatus is rather gradual with alternating periods of higher or lower abundance. In the Rubio-road section (Venezuela) (Fig.3) the base of M. annulatus is rather well defined, but this is a stratigraphically condensed section. In well Icotea-I (Venezuela) (Fig.4), the increase is much more gradual. Since it is known that this well penetrates a very thick Eocene section without any marked gaps, the record shown here is probably a good reflection of the rather irregular increase in Monoporites annulatus in this part of the world. In Nigeria the M. annulatus Zone in the Ovim Bende section (Fig.ll) also shows a well-pronounced base, but in the Imo-river section (Fig.10) the base is less distinct. In Borneo the base has not yet been accurately fixed stratigraphically. M. annulatus is absent from all Upper Cretaceous and Paleocene sediments examined so far and is known to occur throughout the Neogene. Its base can, therefore, be expected within the Eocene there also. 236
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
The boundary with the overlying Verrucatosporites usmensis Zone is defined by the first occurrence of Verrucatosporites usmensis. However, there is a fairly wide interval in which transitional forms between Verrucatosporites usmensis and the presumed ancestral forms with a low verrucation occur. Moreover, there is evidence that the increase in number of Verrucatosporites usmensis takes place earlier in Nigeria than in the Caribbean area. Consequently this boundary is not a sharp one. In the Caribbean area the base in the occurrence of Cicatrieosisporites dorogensis appears consistently to be below the base of V. usmensis and serves as a useful additional criterion. In the Paz del Rio section (Colombia) (Fig.l), the Verrucatosporites usmensis Zone is thus characterized by regular occurrences of Cicatricosisporites dorogensis and scattered occurrences of Verrucatosporites usmensis. In the Ovim Bende and Imo-river sections (Nigeria) (Fig. 10, 11), the boundary between the Monoporites annulatus Zone and the Verrucatosporites usmensis Zone is sharply defined as these sections are incomplete, while in Benin West-I (Fig.12) the change is slightly more gradual. In Borneo the boundary has not been sufficiently studied as yet. The boundary between the Verrucatosporites usmensis Zone and the overlying Magnastriatites howardi Zone is marked by the first appearance of Magna-
striatites howardi. In the Paz del Rio section (Colombia) (Fig.l) this boundary is sharply defined, in Chafurray-3 (Colombia) (Fig.2) less so. In Benin West-1 (Nigeria) (Fig.12) a well-defined boundary ispresent, but in the Imo-river section (Fig.10) recognition of the Magnastriatites howardi Zone depends on a rare occurrence of M. howardi in one sample only. In Borneo the stratigraphical position of this boundary has still to be clarified. The boundary with the overlying Crassoretitriletes vanraadshooveni Zone is marked by the base of the regular occurrence of Crassoretitriletes vanraadshooveni. In Chafurray-3 (Colombia) (Fig.2), this boundary is weakly pronounced, but in B-188 (Venezuela) (Fig.6), a sharply defined base is present. In Okoloma-1 (Nigeria) (Fig.13), the base is rather well defined. In Borneo the base of the occurrence of Crassoretitriletes vanraadshooveni more or less coincides with the base of Florschuetzia levipoli and is slightly older than in the Caribbean area. The youngest boundary is the base of the Echitricolporites spinosus Zone and is marked by the base of the regular occurrence of Echitricolporites spinosus. In B-188 (Venezuela) (Fig.6) and in CO-85 (Trinidad) (Fig.7) the boundary is well defined. In Lubara Creek-2 (Nigeria) (Fig.14) the increase in Echitricolporites is gradual and fairly irregular, and the location of the boundary is, therefore, difficult to determine. Rev. Palaeobotan.Palynol., 6 (1968) 189-348
237
Transatlantic zones The pantropical Proxapertites operculatus Zone can be subdivided in the Caribbean area and in Nigeria into three transatlantic zones. The oldest is the Proteacidites dehaani Zone. This zone is characterized mainly by the co-occurrence of Proteacidites dehaani and Buttinia andreevi, together with high percentages of Foveotriletes margaritae. The boundary with the overlying Retidiporites magdalenensis Zone is taken at the top occurrence of Proteacidites dehaani. In the Rubio-road section (Venezuela) (Fig.3) this boundary is well defined. In Egoli-I (Nigeria) (Fig.9) the boundary is also rather well marked, mainly, however, by the decrease in Buttinia andreevi, which was absent in the previous section, although it is known to occur elsewhere in the Caribbean area within the zone. The Retidiporites magdalenensis Zone is mainly negatively characterized by the absence of Proteacidites dehaani and Buttinia andreevi. Foveotriletes maragritae is still fairly frequent, although it may diminish in abundance in the higher part of the zone. The zone is further characterized in both areas by the regular presence of Retidiporites magdalenensis, Echitriporites trianguliformis, and Proxapertites
operculatus. The boundary between the Retidiporites magdalenensis Zone and the overlying Retibrevitricolpites triangulatus Zone is marked by the first appearance of Retibrevitricolpites triangulatus, Striatricolpites catatumbus, and Psilatricolporites
crassus. In the Rubio-road section (Venezuela) (Fig.3) this boundary is clearly defined. In the Ovim Bende section (Nigeria) (Fig.l l) the boundary is also fairly distinct. In western Venezuela this boundary is further marked by the first appearance of Retitricolpites irregularis and the disappearance of Retidiporites magdalenensis, Proxapertites cursus, Bombacacidites annae, Ctenolophonidites lisamae, and Foveotricolpites irregularis. It is assumed that this pronounced floral change coincides with an unconformity. The pantropical Magnastriatites howardi Zone can further be subdivided both in northern South America and Nigeria into two transatlantic zones, the Cicatricosisporites dorogensis Zone and the overlying Verrutricolporites rotundiporis Zone. The boundary between these two zones is marked by the more or less simultaneous decrease in Cicatricosisporites dorogensis and increases in Verrutricolporites rotundiporis and in Zonocostites ramonae. In Chafurray-3 (Colombia) (Fig.2) this boundary is well marked, but in Benin West-1 (Nigeria) (Fig.12) only one sample was available, which could be assigned to the Verrutricolporites rotundiporis Zone, and the evidence here is not as strong. 238
Rev. Palaeobotan.Palynol., 6 (1968) 189-348
Preliminary results indicate that the major increase in Zonocostites ramonae in Borneo takes place roughly at an equivalent stratigraphical level. The other two marker species do not occur here.
Intracontinental zones Caribbean area In the Caribbean area the transatlantic Retidiporites magdalenensisZone can be subdivided into three units. The oldest unit is the Foveotriletes margaritae Zone, which is characterized by the co-occurrence of frequent Stephanocolpites costatus, Foveotriletes margaritae, Longapertites vaneendenburgi, and Gemmastephanocolpites gemmatus, and by the absence of Bombacacidites annae and
Ctenolophonidites lisamae. The boundary with the overlying Ctenolophonidites lisamae Zone is taken at the first occurrence of Ctenolophonidites lisamae and Bombacacidites annae, and this zone is further characterized by the regular presence of Gemmastephanoeolpites gemmatus, diminishing quantities of Foveotriletes margaritae, and the regular presence of Proxapertites cursus. The base of the youngest Foveotricolpites perforatus Zone is defined by the first occurrence of Foveotricolpites perforatus, which species is restricted to the zone. Bombacaeidites annae and Ctenolophonidites lisamae are frequent in this zone, while Stephanocolpites costatus, Foveotriletes margaritae and Gemmastephanocolpites gemmatus have virtually disappeared. This subdivision is clearly visible in the Rubio-road section (Venezuela) (Fig.3). The Monoporites annulatus Zone can be subdivided in the Caribbean area into four units. The boundary between the Psilatricolporites crassus Zone and the overlying Psilatricolpites operculatus Zone is taken at the lowest occurrence of Psilatricolpites operculatus, as visible in Icotea-1 (Venezuela), (Fig.4) and the Prevenci6n section (Venezuela) (Fig.5). The next higher boundary between the Psilatrieolpites opereulatus Zone and the Retitricolporites guianensis Zone is placed at the base regular occurrence of Retitricolporites guianensis. This boundary is present in the Prevenci6n section (Venezuela) (Fig.5). The Verrutricolporites rotundiporis Zone can be subdivided into the Jandufouria seamrogiformis Zone and the overlying Psiladiporites minimus Zone. The boundary between these two zones is marked by the base of the regular occurrence of Psiladiporites minimus, as is visible in B-188 (Venezuela) (Fig.6). The Crassoretitriletes vanraadshooveni Zone can be subdivided in northern South America into the Multimarginites vanderhammeni Zone and the overlying Grimsdalea magnaclavata Zone. The boundary between these two zones is marked by the base of the occurrence of Grimsdalea magnaclavata. This is clearly visible in B-188 (Venezuela) (Fig.6).
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
239
The Echitricolporites spinosus Zone can be subdivided into three zones. The boundary between the Pachydermites diederixi Zone and the overlying Echitricolporites mcneillyi Zone is marked by the base of the regular occurrence of Echitricolporites mcneilly. This boundary is distinct in CO-85 (Trinidad) (Fig.7) and Paria-1 (Venezuela) (Fig.8). The boundary between the Echtricolporites mcneilly Zone and the Alnipollenites verus Zone is placed at the base of the regular occurrence of A. verus. In Paria-1 (Venezuela) (Fig.8) this boundary is well developed.
Borneo In Borneo a local subdivision can be established, based exclusively on the evolutionary development within the genus Florschuetzia (Fig.16). The lowermost zone, FIorschuetzia trilobata Zone, is characterized by the presence of F. trilobata and the absence of younger forms. The zone probably covers the upper part of the Verrucatosporites usmensis Zone and the lower part of the Magnastriatites howardi Zone, but the stratigraphical position of its base has still to be determined precisely. The first development of Florsehuetzia semilobata and F. levipoli marks the base of the next higher Florschuetzia levipoli Zone, which coincides approximately with the weakly defined base of the Crassoretitriletes vanraadshooveni Zone. In this zone FIorsehuetzia trilobata decreases in numbers, while F. semilobata disappears. The average size of F. levipoli increases also from 30 /z to 35 /~. The overlying Florschuetzia meridionalis Zone is characterized by the regular presence of F. levipoli and, in increasing quantities, of F. meridionalis, while the average size of both species shows further increases. Florschuetzia trilobata is still present in the lower part of this zone, but disappears soon. The boundary between the Florschuetzia levipoli and Florschuetzia meridionalis Zones coincides approximately with the base of the Echitricolporites spinosus Zone, and the first regular occurrence of E. spinosus and Florschuetzia meridionalis can be taken as a criterion for its recognition. Both species have the disadvantage that in the very thick Miocene sediments of northwestern Borneo, their increase in number is gradual, which makes it impossible to recognize a sharp boundary.
INDEPENDENT DATING In the virtual absence of any age-indicating plant macrofossil evidence with which the palynological data could be correlated, associated animal fossils provide the only check on the age of the proposed zones. For this purpose most reliance has been placed on the age-indicating Foraminifera and, to a lesser extent, on 240
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
.(.<
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the Mollusca. Not all areas investigated have produced a sufficient number of check points and it has also only rarely been possible to tie a floral change closely to a faunal change. In general, however, the available evidence indicates that the floral zones recognized are not markedly diachronous over the areas in which they are considered valid. The boundaries between the zones, however, can only rarely be sharply defined, and may not be exactly isochronous over larger distances. Future detailed studies will no doubt provide further evidence to narrow down the gaps in knowledge which still exist. In the account given below the floral zones will be discussed chronologically, a list being given of the age-indicating animal fossils, the faunal zones of which these are characteristic and, as far as possible, the standard time-stratigraphical units with which the zones are correlated. For the Palaeogene this is reasonably well established, but for the Neogene considerable uncertainty still exists, and no attempt will be made to relate the palynological zonation to the European stages. Instead the planktonic zonation established by BOLLI (1966) will be taken as yardstick and his subdivision in terms of Oligocene, Lower, Middle and Upper Miocene and Pliocene is adopted as a fair approximation. For Borneo reference is made to the well-known letter classification of Van der Vlerk and Umbgrove (ref. LIECHTI, 1960). Nomenclature of Foraminifera is according to LOEBLICH and TAPPAN (1964). It was not possible to present a full documentation for this part of the present paper, except for those sections shown for the purpose of defining the zonation and in which the occurrence of age-indicating fossils is recorded. However, in all other instances where a palynological zone is mentioned as associated with certain animal fossils, this is based on actual co-occurrence in the same sections.
(a) Proteacidites dehaani Zone In western Venezuela and Colombia this zone is associated with the smaller Foraminifera GIobotruncana gansseri, G. lapparenti, G. stuarti, Guembelitria eretacea, Siphogeneroides bramletti, and the ammonite Sphenodiscus sp. In Nigeria it is associated with the smaller Foraminifera Bolivina afra, Rugoglobigerina rugosa, and striate Heterohelix spp., with the ammonites Didymoceras sp., Libyoceras ismaeli and Sphenodiscus sp., and with the lamellibranchiat Inoeeramus sp. This faunal list clearly indicates a Maastrichtian age. So far no evidence of an older age has turned up, but since the lower limit of the Proxapertites opereulatus Zone has not been properly studied, the lower part of the Proteacidites dehaani Zone may of course be older than Maastrichtian. Unfortunately, both in Nigeria and in the Caribbean area, the top of the Proteacidites dehaani Zone is present in a predominantly coastal facies without 242
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
sufficient marine fossils, and, therefore, cannot be closely correlated to the top of the Maastrichtian. However, the presence in Nigeria of Danian fossils in the lower part of the overlying zone suggests that this top closely coincides with the top of the Maastrichtian.
(b) Retidiporites magdalenensis Zone The presence, in the lower part of the Retidiporites magdalenensis Zone of Nigeria, of the smaller Foraminifera Globigerina compressa and G. daubjergensis, which are markers for Stolk's Globigerina compressa range Zone, indicates a Danian age for part of this interval (SToLK, 1963). A slightly younger age is indicated by the presence in the higher part of the Retidiporites magdalenensis Zone in Nigeria of the smaller Foraminifera Globorotalia pseudomenardii, G. velascoensis and G. acuta, markers for Stolk's Globorotalia acuta/GIoborotalia velascoensis range zone, of Paleocene age. This and the fact that the lower part of the overlying Retibrevitricolpites triangulatus Zone still is of Paleocene age, indicates a Danian/Paleocene age range for the Retidiporites magdalenensis Zone. In Borneo a Paleocene age for part of the Proxapertites operculatus Zone is indicated by the presence of the smaller Foraminifer Globorotalia velascoensis and the larger Foraminifera Miscellanea miscella and Nummulites nuttalli.
(c) Retibrevitricolpites triangulatus Zone In Colombia the lower part of this zone is associated with the larger Foraminifer Actinosiphon barbadensis, indicating a Paleocene age. In Nigeria the lower part contains the smaller Foraminifera Globorotalia velascoensis, and G. acuta, also indicative of Paleocene, while in the higher part the smaller Foraminifera GIoborotaliaformosa and Globorotalia rex, which are markers for Stolk's Globorotalia.formosa range zone, indicate an Early Eocene age. In view of the fact that in Venezuela the overlying Psilatricolporites crassus Zone carries already a Middle Eocene fauna, while in Nigeria the overlying Monoporites annulatus Zone is associated with a Lower-Middle Eocene fauna, it is suggested that the Retibrevitricolpites triangulatus Zone ranges from Late Paleocene to Early Eocene in age.
(d) Monoporites annulatus Zone (not subdivided) In Nigeria this zone is associated with the smaller Foraminifer Cassigerinelloita amekiensis and associated planktonic Foraminifera indicative of Stolk's Cassigerinelloita amekiensis range zone of late Early-Middle Eocene age. In the Caribbean area a more detailed tie-in of the subdivision has been possible, and this will be discussed separately for each subzone below. Rev. Palaeobotan. Palynol., 6 (1968) 18%348
243
(e) Psilatrieolporites crassus Zone In Venezuela the lower part of this zone is associated with the larger Foraminifera Linderinafloridensis, Helicostegina gyralis and Lepidocyclina sp. A, while the upper part was found to contain Helicolepidina spiralis form C. According to VAN RAAOSHOOVEN (1951), these faunal associations indicate an early Middle and a late Middle Eocene age respectively.
(f) Psilatricolpites operculatus and Retitricolpites guianensis Zones In Venezuela these zones are associated with Helicolepidina spiralis form C and are, therefore, of late Middle Eocene age.
(g) Boundary Monoporites annulatus Zone/Verrucatosporites usmensis Zone Since the lowermost part of the overlying zone in Venezuela still is of late Middle Eocene age, this boundary must be situated in the Middle Eocene.
(h) Verrucatosporites usmensis Zone In Venezuela the presence in the lowermost part of Helicolepidina spiralis form C is still indicative of a Middle Eocene age, but for the upper part the larger Foraminifera Lepidocyclina pustulosa, Pseudophragmina mirandana, Nummulites striatoreticulata and Helicostegina soldadensis and, in Colombia the smaller Foraminifer Bulimina jacksonensis, indicate a Late Eocene age. In Nigeria the presence of the smaller Foraminifera Chiloguembelina martini and Truncorotaloides rohri, indicative of Stolk's Chiloguembelina martini-C. cubensis concurrent range zone, indicates a late Middle-Late Eocene age. The well-known Late Eocene mollusc fauna, originally described by Bullen Newton (ref. REYMENT, 1965) from the higher part of the Bende-Ameki Group, also falls within this zone. In the absence of any evidence of an Oligocene age, an age range for the Verrucatosporites usmensis Zone from Middle to Late Eocene, possibly including the earliest Oligocene, appears reasonable.
(i) Cicatricosisporites dorogensis Zone In the Caribbean area the presence of the smaller Foraminifera Globigerina ampliapertura, G. ciperoensis ciperoensis, Globorotalia opima opima and G. kugleri, and in Nigeria Globigerina ciperoensis ciperoensis, G. ciperoensis angulisuturalis and Globorotalia kugleri indicates an age range for the Cicatricosisporites dorogensis Zone spanning the interval Cassigerinella chipolensis/Hastigerina micra 244
Rev. Palaeobotan. PalynoL, 6 (1968) 189-348
Zone-Globorotalia kugleri Zone of BOLLI (1966). Accepting Bolli's age assignment of this interval, it is concluded that the Cicatricosisporites dorogensis Zone largely coincides with the Oligocene.
(j) Boundary Florschuetzia trilobata Zone/Florschuetzia levipoli Zone This well-marked boundary in Borneo was found to be situated at a level slightly above the boundary Tertiary e 1-4/Tertiary e 5 on a combination of evidence from larger and smaller Foraminifera. In the present paper the latter boundary is taken as coinciding with the Oligo-Miocene boundary, but it is realized that this needs further confirmation.
(k ) Jandufouria seamrogiformis Zone This zone is associated in the Caribbean area with the smaller Foraminifera
Catapsydrax stainforthii and Globigerinatella insueta, and approximately covers the Catapsydrax dissimilis, C. stainforthi and part of the Globigerinatella insueta Zones of Bolli (Lower Miocene).
(l) Psiladiporites minimus Zone In this zone the smaller Foraminifera Globigerinatella insueta, Globorotafia fohsi barisanensis, G. fohsi fohsi and Orbulina universa indicate that part of the Globigerinatella insueta, the whole of the Globorotalia fohsi barisanensis and part of the Globorotalia fohsifohsi Zones of Bolli are covered (Lower Miocene).
(m) Verrutricolporites rotundiporis Zone (unsubdivided) In Nigeria the presence of Globorotalia fohsi fohsi and Orbulina universa indicates that Bolli's Globorotalia fohsi fohsi, Globorotalia fohsi lobata and Globorotalia fohsi robusta Zones may possibly be covered, but since in the Psiladiporites minimus Zone of the Caribbean area no evidence of the latter two zones is present, it seems likely that in Nigeria only the Globorotaliafohsifohsi Zone is represented in the upper part of the Verrutricolporites rotundiporis Zone. Due to unsuitable facies conditions, the Globigerinatella insueta and Globorotalia fohsi barisanensis Zones have not been found in Nigeria.
Stratigraphic position of the base of Orbulina universa In view of the considerable importance which is generally attached to this datum, its location in the different areas will be discussed separately. In the Caribbean area, as well as in Nigeria and Borneo, it has been found to lie in the upper part of the Magnastriatites howardi Zone. In the Caribbean area
Rev. Palaeobotan.PalynoL, 6 (1968) 189-348
245
it can be pinpointed more closely and was found to lie in the Psiladiporites minimus Zone. In Nigeria it is present in the Verrutricolporites rotundiporis Zone, while in Borneo it was found in the middle part of the Florschuetzia levipoli Zone. In Bolli's scheme the base of Orbulina universa occurs in the upper part of the Globigerinatella insueta Zone.
(n) Multimarginites vanderhammeni Zone The presence of the smaller Foraminifera Globorotalia fohsi fohsi and G. fohsi Iobata is indicative of Bolli's Globorotalia fohsi fohsi and Globorotalia fohsi lobata Zones (Lower Miocene).
(o) Grimsdalea magnaclavata Zone This zone was found to contain the smaller Foraminifera Globorotalia fohsi robusta, G. mayeri and G. menardii and thus covers approximately the Globorotalia fohsi robusta, Globorotalia mayeri and Globorotalia menardii Zones of Bolli. The boundary between Lower and Middle Miocene would thus be present within the zone.
(p) Crassoretitriletes vanraadshooveni Zone (not subdivided) In Nigeria the presence of the smaller Foraminifera Globorotalia fohsi fohsi and Orbulina universa indicates a possible age range covering BoUi's Globorotalia fohsi fohsi, Globorotalia fohsi lobata and Globorotalia fohsi robusta Zones. This corresponds well with the more detailed evidence discussed under the two preceding Caribbean subdivisions of the Crassoretitriletes vanraadshooveni Zone.
(q) Florschuetzia levipoli Zone The age range of this Bornean zone is determined by the presence, in the lower part, of the smaller Foraminifer Globigerinatella insueta, indicative of Bolli's Catapsydrax stainforthi and Globigerinatella insueta Zones, in the middle part, of the larger Foraminifer Flosculinella bontangensis, indicative of Tertiary f 1, and of the smaller Foraminifera Globorotalia fohsi barisanensis, G. foshi fohsi and Orbulina universa, indicative of Bolli's Globorotalia fohsi foshi Zone, and, in the upper part, of Globorotalia fohsi lobata, G. fohsi robusta and G. menardii, indicative of Bolli's Globorotalia fohsi robusta and Globorotalia menardii Zones.
(r) Echitricolporites spinosus Zone (not subdivided) In Borneo the lower part of this zone carries the smaller Foraminifer Globorotalia menardii, indicating an age younger than Bolli's Globorotalia fohsi lobata 246
Rev. Palaeobotan. PalynoL, 6 (1968) 189-348
Zone, while in the upper part Pulleniatina obliquiloculata occurs, which is generally taken to indicate a Pliocene age. In the Caribbean area the latter Foraminifer is not found below the Echitricolporites mcneillyi Zone, suggesting that the Mio-Pliocene boundary may be close to the base of the last-mentioned zone. The youngest boundary in the Caribbean area, between the Echitricolporites mcneillyi and Alnipollenites verus Zones is, in view of the climatological interpretations, taken as closely coinciding with the Plio-Pleistocene boundary. Summarizing the results presented in the foregoing account, it may be stated that the top Maastrichtian, top Paleocene, top Lower Eocene, top Middle Eocene, top Upper Eocene and top Oligocene are well established in correlation with the palynological succession. The subdivisions in the Miocene up to the Mio-Pliocene boundary are less accurately known, mainly due to uncertainties remaining in the correlation of BOLLI'S (1966) planktonic zonation and of Van der Vlerk and Umbgrove's letter classification (re['. LI~CHTI, 1960) in the Far East with the standard European succession. On the general range chart (Fig. 15) the proposed correlation of the standard time-stratigraphical subdivision with the palynological subdivision is presented. Zones have been drawn approximately to an absolute time scale, derived from FUNNEL (1964). Two points should be mentioned here in connection with this chart. In the first place, the bases of the occurrences of Verrucatosporites usmensis and Crassoretitriletes vanraadshooveni have proven to be slightly diachronous, as discussed earlier. In the former case, the base occurrence in Nigeria has been taken as the lower limit of the Verrucatosporites usmensis Zone, while the timeequivalent horizon in the Caribbean area is approximately given by the base of Cicatricosisporites dorogensis. In the latter case, the base occurrence in the Caribbean area has been taken as the lower limit of the Crassoretitriletes vanraadshooveni Zone, since this is the best defined change in relation to the planktonic subdivision. Secondly, the detailed subdivision of the Eocene and Lower Miocene reflects local stratigraphical needs more than rapid floral change. The relatively long, unsubdivided Oligocene interval probably indicates lack of information due to a hiatus in the stratigraphical record of both the Caribbean area and Nigeria. In Borneo the Eocene interval has not yet been adequately investigated and no subdivision is possible at present.
STRATIGRAPHICAL APPLICATION
In this chapter the practical application of the palyno-stratigraphical evidence Rev. Palaeobotan. Palynol., 6 0968) 189-348
247
will be discussed and illustrated with three geological cross-sections from the Caribbean area (Fig.17-19). The sections chosen have been constructed as far as possible on the basis of wells or measured surface sections in which a fairly detailed palynological succession had been established. In a few cases a composite section had to be constructed by piecing together various scattered shorter sections, so that thicknesses of formations are consequently less reliable. Nomenclature of geological formations follows as far as possible generally accepted terminology. For Venezuela reference is made to the respective volume of the International Stratigraphic Lexicon (SCHWARCKANGLADE, 1956), for Colombia and Trinidad to more scattered literature. The environment of deposition has been broadly classified into three units: (1) upper coastal plain (fresh water), and more inland environments characterized by the absence of any brackish or marine faunal elements; (2) lower coastalplain (brackish water), deposits which may carry typical faunal associations indicating low and variable salinity; (3) marine. Section I (Fig.17) covers the Palaeogene from east-central Colombia to western Venezuela, running along the northern slopes of the Andes, circling around Lake Maracaibo to turn southwards along the Perija foothills as far as the Tarra area. A large part of the area covered by this section is underlain by marine Cretaceous deposits. The Colombian sections have not reached these, but in Venezuela the Col6n, Mito Juan and their lateral equivalent the La Paz Shales have been sampled and found to be restricted to the Proteacidites dehaani Zone. In the north a slightly younger marine deposit is the Guasare, covering the Foveotriletes margaritae and Ctenolophonidites lisamae Zones. The regression shown to have taken place by the change towards a transitional or even terrestrial environment has evidently not been contemporaneous, a phenomenon earlier described in a generalized way by KUYL et al. (1955). South of Lake Maracaibo, the sediments assigned to the Proteacidites dehaani Zone were already deposited in part in a transitional environment, as indicated by the Umir in Colombia and the lower part of the Orocu6 in Southwestern Venezuela. Further north in the Dibujo area (Riecito Mach6), the change from marine to terrestrial deposits takes place at the base of the Foveotricolpites perforatus Zone. The effect of tectonic movements during the Paleocene is also clearly visible. The interval Foveotriletes margaritae Zone-Foveotricolpites perforatus Zone is thickest in the Lebrija section and shows very regular thinning to the south and northeast. Along the Andean foothills (Fig. 17, columns 3-7) and in the northern Lake and Concepci6n areas (columns 8-10) the Paleocene has been truncated, indicating a minor orogenic phase separating Paleocene from Eocene. This truncation is least noticeable in the Riecito Mach6 section, where the possibility of continuous 248
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
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sedimentation is not excluded, although the rather sharp and distinct floral change at the base of the Retibrevitricolpites triangulatus Zone still suggests the presence of a hiatus. It increases southwards since, in Concepci6n, the Foveotricolpites perforatus Zone is missing, while in the North Central Lake area the Ctenolophondites ilsamae Zone is also missing, and it reaches maximum values along the northern Andean foothills. In Rio Mullapas and Rio Perdido the Proteacidites dehaani Zone is found underlying the Eocene, and the whole Paleocene appears to be missing. In a southwesterly direction the magnitude of the hiatus rapidly decreases again and in Quebrada La Mora the Foveotricolpites petforatus Zone is found again. Further south and in the Tarra area the top of the Paleocene interval coincides with the base of the Mirador Sandstone, and it is likely on geological grounds that a minor unconformity is present at this level (ScHAuB, 1948, p.225), coinciding with the base of the Retibrevitricolpites triangulatus Zone. In Colombia sampling gaps around this level preclude any definite statements on this problem. The Eocene sedimentation cycle starts with the Retibrevitricolpites triangulatus Zone. (As mentioned in the previous section of" this paper the lowermost part of this zone may be of Paleocene age.) Sediments assigned to this zone are thickly developed in the northeast and in Colombia, but they are absent along the northern Andean foothills between Rio de Oro and Rio Mullapas. The next higher Psilatricolpor#es crassus Zone is absent between Rio Perdido and Rio de Oro and in the Colombian sections. The overlying Psilatricolpites operculatus Zone is generally rather thin and its absence in sections with reduced sedimentation such as Rio Mullapas and Quebrada La Victoria may be due to sampling gaps. In contrast to the rather restricted areal distribution of the older Eocene zones, it is clear that the overlying Retitricolporites guianensis and especially the Verrucatosporites usmensis Zones have a much wider distribution. The former is thickly developed in the Rio Mullapas and Rio Lebrija sections, while the latter is found in more or less uniform thickness m all the northern Andean foothills sections as well as in T~ichira. The absence of one or both zones in Rio Mullapas, North Central Lake and Concepci6n is due to truncation by the well-known post-Eocene unconformity. From these observations it may be deduced that during the Eocene progressively younger sediments transgressed over an eroded Paleocene surface, first localized in the deeper parts of the sedimentary basin, but rapidly transgressing over virtually the whole area of investigation in the upper part of the Retitrico# porites guianensis Zone and especially during the time of deposition of the Verrucatosporites usmensis Zone. This last transgressive phase coincides with the widespread deposition of the marine Pauji in the east, which sharply contrasts with the transitional environment prevalent in the older Eocene. It must be noted that in the southwestern part this transgressive younger Eocene rests unconformably on Lower Eocene sediments of Retibrevitricolpites triangulatus-Psilatricolporites crassus Zone age, indicating a minor orogenic phase, Rev, Palaeobotan. Palynol., 6 (1968) 189-348
263
probably resulting in a slight subsidence accompanied by a southwestern tilt of the depositional basin. Thus in Quebrada La Mora the Verrucatosporites usmensis Zone is resting on the Ctenolophonidites lisamae Zone, in Rio de Oro on the Foveotricolpites perforatus Zone and in the Rubio road section already on the Psilatricolporites crassus Zone. In general Eocene sedimentation was thickest in the northeast, as shown by the Catanejo-Prevenci6n section. Continuation of the Eocene sedimentary basin towards Falc6n is likely, but no palynological data are available from this area due to carbonization of plant material. At this point it may be mentioned that, although the strong vertical exaggeration of the section suggests the presence of marked angular unconformity at many places, in reality this can hardly ever be observed in the field. Moreover, the similar lithologies of the formations on both sides of the unconformities and the absence of other age-indicating fossils made it virtually impossible to unravel the geological history in detail before the advent of palynological studies (cf. SCHAUB, 1948; MENCHER et al., 1953). The situation was further complicated by the presence of various sandstone bodies, which had been correlated merely on lithological similarities supported by weak photogeological evidence. The three main sandstone bodies are the La Sierra in the northwest, the Misoa in the southeast and the Mirador in the southwest. Palynological studies revealed that the bulk of the Mirador Sandstone had been deposited in the interval Retibrevitricolpites triangulatus-Psilatricolporites crassus Zone and was, therefore, roughly contemporaneous with the C-sand group of the Eocene terminology used in the Lake Maracaibo area, while both the La Sierra and Misoa Sandstones are mainly deposited in the interval upper Psilatricolporites crassus-Retitricolporites guianensis Zone, thus being markedly younger and equivalent to the B-group of sands in the Lake area. In addition, as already pointed out by SCHAUn (1948,p.224), the Mirador Sandstone cannot be traced in the field along the northern Andean foothills beyond T~ichira, and earlier attempts to do so were based on miscorrelation either with underlying Paleocene sandstone bodies equivalent to the Barco Sandstone member or with basal Upper Eocene sandstones transgressing over the eroded Paleocene surface. As can be seen on section I in the area between Rio de Oro and Rio Perdido, (Fig.17), due to the considerable gap shown to be present by palynology, these sandstones are close together and can easily be confused in the field or by photogeology. A further complication is present in the Tarra area southwest of Lake Maracaibo, where the onlapping La Sierra Sandstone comes into contact with the underlying Mirador Sandstone. It has been shown by palynological dating that in some areas, Quebrada La Victoria for example, the uppermost part of what had been called Mirador Sandstone is in fact the age-equivalent of the lowermost La Sierra Sandstone and that locally a minor hiatus may thus exist in the upper part of the Mirador. 264
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
These observations also have some consequences for the stratigraphical terminology. First of all, the boundary between the Carbonera and the Orocu6 Formations is distinct only when these formations are separated by the Mirador Sandstone, as is the case in T~ichira and the Tarra area. However, the disappearance of the Mirador in a northeasterly direction along the Andean foothills and the similar facies of the Orocu6 and Carbonera make it virtually impossible to separate these formations in the field. On the section the boundary between the formations has in such cases been taken to coincide with the stratigraphical hiatus revealed by palynology and indicated with a dotted line. Similarly the lithological separation of the Mirador and La Sierra Sandstones in the area of overlap is difficult, and recognition of these different sandstone bodies may only be possible when shale intercalations carry sufficient pollen for dating. Recently GONZALEZ(1967) has studied the transition Los Cuervos-Mirador in the Barco area (Colombia). He reports the presence of Cicatricosisporites dorogensis rather low in the Mirador Sandstone, which suggests that a relatively large part of this formation can be assigned to our Verrucatosporites usmensis Zone. However, the lack of data from the upper 100 m of the Mirador Sandstone, the absence of Retitricolporites guianensis and Perisyncolporites pokornyi, several other anomalies in the floral succession and the rather restricted number of samples of unknown quality preclude a more definite interpretation of his results. The final phase of Eocene sedimentation, where preserved, indicates general regression of the sea. In the Catanejo-Prevenci6n area the marine-deltaic Eocene sediments are succeeded by the continental La Victoria Formation. In the area between Rio Lebrija and Rio Perdido the Esmeralda and Carbonera Formations show no sign of transgression and in the Paz del Rio section the transitional San Fernando Formation, which is roughly time-equivalent to the marine Pauji transgression phase, is succeeded by the Oligocene continental Margua Formation. The regression here has taken place during the time of deposition of the Cicatricosisporites dorogensis Zone and is, therefore, younger than in the CatanejoPrevenci6n area where the La Victoria Formation is restricted to the Verrucatosporites usmensis Zone. In the Rio de Oro and Rio Perdido sections the Le6n Shale at the transition between the Verrucatosporites usmensis and Cicatricosisporites dorogensis Zones indicates a localized more pronounced subsidence, without marine influences. Section II (Fig.18) covers the older Neogene part of the stratigraphical succession and runs from the western Llanos area in Colombia to southwest Venezuela, crosses Lake Maracaibo and traverses Falc6n from west to east. The top of the San Fernando Formation, which in most sections can be found around base Cicatricosisporites dorogensis Zone, appears in the Rio Cubug6n to lie close to the top of the zone, thus indicating that the Le6n Shales of the La Fria area may be a lateral equivalent of the upper part of the San Fernando. In Rev. Palaeobotan. Palynol., 6 (1968) 189-348
265
Falc6n marine deposits characterize the Cicatricosisporites dorogensis Zone, while in well B-188 no evidence of the occurrence of this zone could be found. Possibly the barren Icotea Formation represents this interval. In the south the period of deposition of the San Fernando and of the Le6n Formations is followed by a regressive period, starting earliest in Voragine-l. No trace of this regression can be detected in Falc6n. Then, approximately in the middle of the overlying Verrutricolporites rotundiporis Zone (Jandujburia seamrogiformis Zone, upper part), a rather pronounced transgressive phase can be discerned. This is the well-known La Rosa transgression from the Bolivar coastal area of Lake Maracaibo, which can be followed from the marine Agua Clara in Falc6n, via the La Rosa of the Maracaibo basin, towards the Uracil fossil horizon of La Fria, which here occurs intercalated in the terrestrial Guayabo Formation. In Colombia this transgression is visible as a marine intercalation in the lower part of the Cubug6n Formation of the Rio Cubug6n and in the lower part of the Chafurray in well Chafurray-3. Voragine-I was situated more inshore and no marine interval occurs here. It has already been pointed out by Scr~atm (1948) and MENCHER et al. (1953) that this La Rosa transgression is nowhere connected with any disconformity. Its contemporaneity shows that during a short time a continuous seaway was present from east Falc6n as far south as Chafurray-3 in the Colombian Llanos. In the upper part of the Verrutricolporites rotundiporis Zone (Psiladiporites minimus Zone) a regression took place which can be recognized from the south as far as north central Falc6n in the transitional-continental deposits of the Chafurray, Caja, Cubug6n, Guayabo, Lagunillas and Cerro Pelado Formations, respectively. In the south, only in the Rio Cubug6n, a second transgression is indicated in the Multimarginites vanderhammeni Zone, which may be connected with the marine Querales Formation of north central Falc6n. In younger zones regressive deposits predominate. Only in Falc6n does marine influence persist. While in north central Falc6n the marine environment has been interrupted twice during the Neogene by regressive phases, in east Falc6n sedimentation was continuously marine, which made it possible to arrive at an accurate tie-in between the palynological zonation and Bolli's subdivision on pelagic Foraminifera. Unfortunately the east Falc6n stratigraphical sequence is based on a combination of scattered short sections and stratigraphical thicknesses shown are, therefore, probably not more than rough minimum estimates. As already mentioned, in contrast to the preceding Palaeogene section, no pronounced unconformities could be detected in the Neogene sediments investigated. Still, rather strong variations in thickness are obvious. In Colombia the section penetrated by Chafurray-3 is much more reduced than in Voragine-1. In Rio Cubug6n it is again slightly thicker than Voragine-1, but in the La Fria and Catatumbo areas maximum thicknesses are observed. Remark-
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able are the extremely reduced thicknesses observed in B-188, especially since the floral succession appears complete, without any marked gaps. Thicknesses increase again rapidly, approaching the Falc6n basin, where, in north central Falc6n especially the Verrutricolporites rotundiporis Zone is excessively thick. This second section shows again the great value of palynology as a means of correlating from the marine facies, as present in Falc6n, to the mainly continental environment in southwestern Venezuela and the adjoining part of Colombia. The correlation of the various formations shown on both sections closely corresponds, for the Maracaibo basin, with the correlation chart presented by MILLER et al. (1958). In section III (Fig.19) the stratigraphy of the younger Neogene deposits is traced from northwestern Colombia to Trinidad. Three separate sedimentary basins are represented. In northwestern Colombia an investigation has been made of the area between Sinu and Bayunca, which is separated from the southern Maracaibo lake and Falc6n basin by the Perija mountain range on the border between Colombia and Venezuela. The latter basin is in turn separated from the eastern Venezuela-Trinidad basin by the mountains connecting the M~rida Andes with the coastal range of Venezuela. In these mountainous areas the youngest Neogene deposits have never been present or were eroded during uplift. In view of this geographical separation, the section is best discussed from west to east. In northwestern Colombia the marine sediments in the Sinu basin and near Bayunca are correlated by the Pachydermites diederixi Zone. The total interval covered by these two sections gives a complete succession from the Multimarginites vanderhammeni Zone to the Alnipollenites verus Zone. These isolated marine deposits in northwestern Colombia are correlatable with terrestrial sediments in the southern Lake Maracaibo area. In well Catatumbo-1 the Grimsdalea magnaclavata and Alnipollenites verus Zones can be recognized, but not the boundary between the Pachydermites diederixi and Echitricolporites mcneillyi Zones, which is due to an unfavourable mottled clay facies and to lack of samples. In general sediments are thicker in this area than in northwestern Colombia, and especially in the Rio Buena Vista section the younger zones reach considerable thickness. In contrast, sediment thickness in the older interval Jandufouria seamrogiformis Zone-Multimarginites randerhammeni Zone remains fairly constant, irrespective of facies, as shown by the correlation of Catatumbo-1 with the Rio Onia and Rio Buena Vista sections. This increase in thickness of the youngest sediments in the southern Maracaibo basin is a reflection of tectonic events connected with the approximately contemporaneous rise of the M&ida Andes. As already shown in section II, the younger Neogene sediments in the southern Maracaibo basin are continuous with those in Falc6n, but this sedimentary area was probably separated by a broad land area from the east Venezuelan basin. However, the floral characteristics marking the palynological zones turn UP
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in the same sequence and in a virtually identical expression in both areas, and correlation between the marine Falc6n sequence and well OG-2, where a regressive sequence is present, presents no difficulties. From OG-2 to Trinidad the floristic boundaries again cross facies lines, and in the Catshill-Ortoire area a second tie-in with the zonation on age-indicating pelagic Foraminifera confirms the time-stratigraphical value of the palynological zonation. The younger part of the sedimentary sequence in Trinidad shows rapid changes in thickness and facies over short distances and palynology has been of great value here for unravelling the complex geological history. Of special interest is finally the great thickness attained by the Grimsdalea magnaclavata Zone in the Catshill-Ortoire area of Trinidad. This, together with the presence of large quantities of reworked material and the well-known Lengua boulder beds, reflects the final upward movement of the Andean orogeny, resulting in the upthrust of the Trinidad central range. Of course subdivision of the main floral zones presented here will make it possible to refine considerably the stratigraphical picture presented. This, however, lies beyond the scope of this paper, which was aimed primarily at demonstrating the value of palynological subdivision for regional correlation. Summarizing the results obtained so far, it may be stated that palynological evidence has: (1) shown the presence and magnitude of previously unsuspected stratigraphical gaps; (2) produced positive evidence for correlation of many Tertiary formations lacking age-indicating animal fossils; (3) shown that pollen boundaries can cross facies boundaries and are then eminently suited for palaeogeographical reconstructions. BOTANICAL RESULTS
Although the primary purpose of the palynological studies described here has been stratigraphical, the desirability to relate as far as possible the fossil pollen and spore species to Recent plants has, of course, produced some interesting botanical results. In this section of the present paper the most important results in this respect will be briefly discussed. First of all, the criteria applied in botanical identification must be evaluated. In general three categories were distinguished: (1) Fossil species of which the botanical affinity is wholly obscure, e.g., Buttinia andreevi. Possibly many of these species represent pollen or spores produced by extinct plants. (2) Fossil species which can be referred to more than one, not closely related, groups of plants, while ecological evidence is insufficient to decide which group may have been the parent plant, e.g., Striatricolpites catatumbus. 268
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(3) Fossil species which, because of some unique morphological feature and corroborative ecological evidence, can be confidently assigned to some Recent plant taxon, e.g., Verrutricolporites rotundiporis, derived from Crenea sp. (Lythraceae). In the account given below only the species of category (3) will be discussed. Within this group it may be possible to assign the fossil species to a single taxon, as in the example given above, or the pollen or spore type under discussion may characterize more than one related taxon, e.g., Multiareolites formosus, which pollen type occurs in at least nine genera of Acanthaceae. In the former case it appears justified to use the term Crenea pollen as equivalent to the form species Verrutricolporites rotundiporis. In the latter case the fossil form species can also be referred to as Justicia-type pollen, one of the genera showing the pollen type being selected as indicator. Again the term Justicia type is equivalent to the form species Multiareolites formosus. Only the names of form species and form genera have, of course, taxonomic status.
FILICALES PARKERIACEAE
Ceratopteris ( Magnastriatites howardiJ The source areas of this spore species are the alluvial plain and coastal swamps where the parent plant grows in the shape of a small aquatic fern in shallow water, bordering lakes and river banks. This environment is characterized by rapid local facies changes and this is clearly reflected in the pronounced quantitative fluctuations in fossil coastal plain sediments. In marine sediments the spores are much rarer. The taxonomic identification is thus well supported by the distribution pattern of the fossil spore. The frequency of Ceratopteris spores in the Neogene of all three areas investigated and their absence in older Palaeogene and Cretaceous deposits, shows that the present-day pantropical distribution of this freshwater fern may date only from the mid-Tertiary. This is, however, somewhat in contrast to the isolated systematic position and specialized morphology of the genus, which is assumed to be of great antiquity. Its origin may have been local, but as long as no ancestral spore forms have been found this problem remains unsolved. SCHIZAEACEAE
Mohria type ( Cicatricosisporites dorogensis) This spore type is found in most of the species of Mohria and a few of Rev. Palaeobotan. Palynol., 6 (1968) 189-348
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Anemia (Schizaeaceae). Without further study specific determination is impossible. The spores of this group are, however, clearly distinct from those produced by ferns of the genus Ceratopteris (Parkeriaceae). The Tertiary distribution of the Mokria type can best be discussed in conjunction with what is known of the Cretaceous distribution pattern of their nearest relatives. This discussion refers to the genus Cieatricosisporites s.l., recognizing the considerable difficulties which crop up when specific distinction of the dispersed spores is attempted (cf. HU~HES and MOODY-STUART, 1966). In the Caribbean area the Mohria type is absent from the uppermost Cretaceous, Paleocene and Lower Eocene but MULLER (1966) reports its presence in Cretaceous-Paleocene strata in northeastern Brazil. In the Middle Eocene the ferns producing this spore migrated into northern South America, as shown by its remarkably sharply defined base occurrence in Venezuela. It then remains fairly abundant up to the Oligo-Miocene transition. In the Miocene it virtually disappears from the record. In tropical west Africa it is common in the Albian-Senonian, absent in the remainder of the Cretaceous, and returns in the Upper Eocene, somewhat later than in the Caribbean, but suffering a sharp decrease in the Caribbean at the top of the Oligocene, and disappearing completely at the same level in Nigeria. In Borneo the spore type is abundant in the Lower Cretaceous, decreases in the Upper Cretaceous and becomes very rare in the Tertiary. As is well known, in Europe the type is frequent in the Cretaceous and in the Palaeogene, is still locally abundant in the Oligocene and disappears from the record in the Neogene (cf. KRUTZSCH, 1957). DRUGG (1967) has recently reported its presence in Late Cretaceous Paleocene strata from California. The Recent genera Anemia and Mohria are at present confined to the tropics and subtropics of America, the West Indies, southern and eastern Africa, Madagascar and the Mascarenes, where they occur often in a semi-arid habitat (CHRIST, 1910). From these data it is clear that the group as a whole has had a rather chequered history. In the Early Cretaceous it had a virtually world-wide distribution, but in the Late Cretaceous a contraction of its area occurred. In the Middle Eocene a second expansion of its geographical area took place in Nigeria and in the Caribbean, but the decline at the end of the Oligocene appears to have been world-wide again, leading to the present scattered relic areas of occupation in America and Africa.
Lygodium microphyllum type (Crassoretitriletes vanraadshooveni) Lygodium microphyllum is a climbing fern, common in the humid marsh and swamp forests of west Africa and the Indo-Malesian area, but absent today 270
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in South America. The geological record of the Lygodium microphyllum type indicates rapid pantropical expansion in the Neogene. In the Caribbean area the fern apparently became extinct in the Miocene. The reasons for this rapid expansion and local extinction are entirely obscure. No ancestral spore type is known, but may be present in the insufficiently studied Eocene sediments of the Indo-Malesian area, where the type occurs slightly earlier and may probably increase more gradually during the Neogene than in Africa or in the Caribbean area. The high values of this spore type observed in the latter areas have not been found, however, in the Neogene of Borneo, which is rather in contrast to its present-day abundance in vegetationally disturbed areas and in coastal swamp forests.
ANGIOSPERMAE POACEAE (GRAMINEAE) ( Monoporites annu/atus)
The present-day abundance of grass in the tropics is largely confined to more open vegetation such as is found in coastal savannah's, river valleys, montane areas and in the Caribbean area above all in the Llanos plains. In general a drier climate with marked rainy seasons favours the development of extensive grass areas more than a humid one. The absence of grass pollen in Cretaceous and Paleocene sediments of the tropics, its first occurrence in low percentages in the Eocene and the increase in abundance in the Neogene probably reflect the gradual development of the Poaceae. According to GOTHAN and WEVLAND (1964), the family has been recorded from the Cretaceous of the present-day temperate areas on macrofossil remains. However, DRtJC~ (1967) confirms the absence of grass pollen for the Upper Cretaceous-Paleocene of California. The development of grass vegetation in the present-day tropics may, therefore, have been somewhat later than in the temperate areas. Although specific and generic determinations are hardly possible, it is likely that the increase in quantity of Poaceae pollen occurred simultaneously with an increase in taxonomic variety. The significance of grass pollen for the Tertiary stratigraphy varies according to the area. In Borneo short-lived increases could tentatively be related to phases of igneous activity in the hinterland, resulting in ash showers which may have temporarily destroyed the forest cover of large areas. Any evidence for widespread occurrence of savannah's is lacking in this humid area. In Nigeria major fluctuations in the grass curve probably reflect the shifting boundary between forest and savannah in the lowlands. The greatest abundance of grass pollen has been found, however, in the Caribbean area. Here open vegetation with a dominantly grass-covered soil must
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have been widespread in the Neogene, just as it is today. Source areas may have been the ancient Llanos, coastal savannah's, or alluvial plains in river valleys, such as described by WYMSTRA (1967) from the Magdalena valley in Colombia. That large amounts of grass pollen are produced in such environments is clear from the diagrams presented by WYMSTRA and VAN DER HAMMEN (1966) and WYMSTRA (1967). Transport of pollen could be by river or by air currents. The fact that in Recent Orinoco delta sediments grass pollen proved to be scarce (MULLER, 1959) is due to the dominance of swamp vegetation lacking in grass in the delta area proper. Since human interference can be excluded in the Mio-Pliocene, this is an indication that open vegetation rich in grasses may be originally of entirely natural origin in the tropics, although its wide expanse nowadays is largely caused by man, a conclusion also drawn by WYMSTRA and VAN DER HAMMEN (1966). A parallel development may be seen in the mid-continent area of North America, where the wide expanse of grassy plains is generally also supposed to date from the Neogene. ARECACEAE(PALMAE)
Nypa (Spinizonocolpites baculatus, S. ech&atus) Of this genus, at present restricted to the mangroves of the Indo-Malesian area, a fairly extensive fossil record of both fruits and pollen exists (ref. TRALAU, 1964; MULLER, 1964). The origin of Nypa must be sought in the Upper Cretaceous, since the ancestral pollen type Spinizonocolpites baculatus proved to be present already in the Senonian of all three areas investigated. In Sarawak the earliest records date probably from the post-Turonian (MULLER, 1968). Neither place of origin nor pre-ancestral type are known as yet. It would appear that Nypa early reached a pantropical distribution, which it maintained during the Paleocene and Eocene. The widest extension of range to the north took place during exceptionally warm phases in the Eocene, when it grew along the Tethys shores, as testified by the presence of fossil pollen and fruits. The occurrence of fossil Nypa fruits at latitude 52°N in the London Clay has recently been discussed by VAN STEENIS (1962a,b), who believes them to represent allochthonous drift material, and by TRALAU (1964), who considers the fruits to have been of local origin. This problem is connected with the evaluation of the climate as derived from the well-known London Clay flora. Although the palynological evidence presented here has no direct bearing on this controversy, it may be pointed out that the pantropical occurrence of Nypa in the Eocene makes it likely that it grew at least along the southern shores of the Tethys sea, which, during the warmest phase of the Eocene would certainly have been hot enough for Nypa to grow there. It then remains to be decided by further micro- and macro272
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botanical investigation whether the European fossil fruits were derived by drift from the southern Tethys shore or grew locally for a short time also on the northern shores. The disappearance of Nypa from the Tethys area has probably been caused by decreasing temperature, but the disappearance at the end of the Eocene, both from the Caribbean and Nigeria, as shown by the pollen record, is more difficult to explain. Possibly an increase in aridity, coupled with the development of a more pronounced seasonal climate, may have been operative. BETULACEAE
AInus (Alnipollenites verus) Identification of AInus pollen grains in tropical deposits is always a striking event for a palynologist familiar with temperate floras. The stratigraphical distribution of Alnus pollen in the tropics has clearly been proved to be related to the presence of mountains of sufficient dimensions to provide the temperate climate required and to the connections with more northerly mountain ranges which provided migration routes. In Borneo Alnus pollen was found to be abundant in Oligocene-Lower Miocene sediments associated with a mid-Tertiary orogenic phase. Its gradual decrease in quantity during the course of the later Miocene and Pfiocene could be related to a gradual levelling of the mountains (MULLER, 1966). Immigration must have been from the north in the Palaeogene. In Nigeria Alnus has not been recorded, no doubt due to the absence of suitable north-south mountain connections in the western part of Africa. In the Caribbean area the fairly sudden appearance of Alnus pollen in sediments of Pleistocene age is evidence of the fairly recent immigration of the genus into the Southern Hemisphere, where it occurs at present at altitudes above 1,000 m in the Andes as far west as the coastal range of Venezuela and as far south as Peru. Its migration from the north over the comparatively low mountain ranges of the--by then closed--Panama isthmus was certainly facilitated by the first colder phase of the Pleistocene. PROTEACEAE
Guevina type (Proteacidites dehaani) The presence of this pollen type in Senonian sediments of Nigeria and the Caribbean would indicate a formerly more extended area of certain genera of Proteaceae nowadays mainly restricted to the Southern Hemisphere (Guevina and Lomatia in Chili, Leucospermum in South Africa, Lomatia, Cardwellia and Steno-
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carpus in Australia). It is noteworthy that neither the Guevina type nor any other proteaceous pollen type was found in the Upper Cretaceous and Paleocene of northwestern Borneo (MULLER, 1968). On the other hand, closely related proteaceous pollen was described by BRATZEVA(1965)from the Upper Cretaceous of eastern Siberia and by ANDERSON (1960) from the Upper Cretaceous of New Mexico. These observations would suggest that certain Proteaceae had been able to migrate along the Pacific coast of South and North America, as far as eastern Asia. Their subsequent disappearance from this area must then have taken place at the Cretaceous-Tertiary transition.
OLACACEAE
Anacolosa type (Anacolosidites cf. luteoides) The form genus Anacolosidites may, according to ERDTMAN(1952), comprise pollen derived from the genera Anacolosa, Cathedra and Ptychopetalum (Olacaceae). The first-mentioned genus has a predominantly lndo-Malesian distribution (19 spp.) with only one species (A. unc~fera) described from central Africa and one from Madagascar. The other genera occur in Brazil (Cathedra, 5 spp.) and in tropical America and west Afl'ica (Ptychopetalum, 6 spp.). Pending a complete palynological study of this pollen-morphologically well-characterized group, the fossil types are united here under the Anacolosa type, although some variation in ornamentation of wall is known to exist. The fossil record shows the first occurrence for Australia to be in the Paleocene (HARRlS, 1965). In Borneo the first occurrence is also in the Paleocene (MuLLER, 1968), and the type is regularly present throughout the Tertiary, although a reduction in abundance can be observed in the Mio-Pliocene. In Nigeria the first occurrence is also in the Paleocene, but it is regularly present only UP to the Miocene, after which it becomes very scarce, leading apparently to the present-day rarity of Anacolosa and Ptychopetalum in Africa. In the Caribbean area Anacolosa-type pollen makes its appearance at the Paleocene-Eocene transition and is common only in the Lower and Middle Eocene. In Europe the type has been recorded from the Paleocene and Eocene by ERDTMAN (1954) and KRUSZSCH (1959). From these observations it is clear that as early as Paleocene time the group of olacaceous plants producing the Anacolosa-type pollen (Anacolosa, Cathedra and Ptychopetalum) were widely distributed in Australasia, Africa and Europe, while South America was reached somewhat later. Noteworthy is finally the contraction of area and gradual reduction in abundance during the Neogene. 274
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FABACEAE
(LEGUMINOSAE)--Caesalpinioideae
Caesalpinia type ( Margocolporites vanw(]hei) The earliest record of this highly characteristic pollen type dates from the Middle Eocene in the Caribbean, where it remains present up to Recent. In Nigeria the first appearance is in the Upper Eocene and it is remarkably restricted in its range there, disappearing again in the Lower Miocene. In Borneo it is absent in Cretaceous-Paleocene sediments, but its base is not accurately known. In the Neogene it is fairly common, however. RAMANUJAM (1966) has recorded similar pollen types from the Miocene of south India. Since a number of genera may be represented, it is difficult to be positive about the phyto-geographical significance of these facts. It is possible that Caesalpinia bonduc, which prefers a coastal habitat, has produced a large proportion of the fossil pollen of this type, but in the Caribbean area Caesalpinia coriaria, which is common in the dry thorn forests along the northeastern coast of South America, may also have contributed. Further detailed studies of this group of pollen types will no doubt result in interesting conclusions.
uyACl~AE--Ctenolophoniideae
Ctenolophon The following types can be distinguished: Ctenolophon engleri type (CtenoIophonidites costatus), Ctenolophon type A (Ctenolophonidites lisamae), Ctenolophon parv(folius type (Retistephanocolpites williamsi). The oldest known type at present is the Ctenolophon engleri type, which occurs already in the Senonian of Nigeria, is absent from the Paleocene, but reappears and remains regularly present in younger sediments. The parent plant Ctenolophon engleri is still living in west Africa. A closely similar pollen type, Ctenolophon type A, has a sharply defined base occurrence in the Paleocene of the Caribbean area, but disappears from the record at the Paleocene-Eocene transition. The third pollen type, the Ctenolophon parvifolius type, is first found in Nigeria in the Paleocene, disappearing at the Eocene-Oligocene transition, but present in the Neogene of Borneo, where the parent species C. parvifo#us still lives today. Ctenolophon engleri in Africa and C. parv(folius in the lndo-Malesian area are the only known species of the genus. From these data it is now possible to deduce tentatively the following history for the genus Ctenolophon. Origin probably in Upper Cretaceous time, possibly
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in Africa, followed by an early differentiation into an engleri and parvifolius pollen type, the engleri type remaining present with a short interruption throughout the Tertiary and Quaternary of Africa. Migration of a species with pollen closely related to that of Ctenolophon engleri to South America in the Paleocene, shortly followed by extinction. Migration eastwards of the parv(folius type reaching Malesia probably in the Eocene, becoming extinct in Africa. This history in combination with the peculiar morphology of the pollen grains supports the taxonomical opinion that the genus Ctenolophon is both ancient and sharply differentiated. The pollen types described by A. R. Rao and K. P. Vimal from Indian lignites from Travancore of probably Miocene age and tentatively compared by ERDTMAN (1956) to C. engleri are left out of account here, since descriptions and illustrations are insufficient for proper comparison. MALPIGHIACEAE
Brachypteris type (Perisyncolporites pokornyi) The fossil record for this characteristic pollen type, which occurs in several genera of Malpighiaceae, dates from the Middle Eocene of the Caribbean area. In Nigeria it appears slightly later and remains much more scarce than in the Caribbean area. This is in agreement with present-day distribution of the family, which is best represented in South America, in which continent its origin may have lain. Fruits of Malpighiaceae recorded from the Tertiary of Europe have so far not been accompanied by fossil pollen. The less characteristic pollen of the Malpighiaceae growing in Borneo today, has not yet been found fossil. EUPHORBIACEAE
Alchornea (Psilatricolporites operculatus) The highly characteristic pollen grains of Alchornea are first found in the lower part of the Middle Eocene of the Caribbean area. In Nigeria they appear somewhat later, in the upper part of the Middle Eocene. In Borneo their first origin cannot yet be precisely given. It would appear that the present-day pantropical distribution of the genus was achieved within a comparatively short interval of time in the Eocene.
Amanoa type (Retitricolporites irregularis) This pollen type appears at the base of the Eocene in the Caribbean area and in Nigeria. It is most likely that the genus Amanoa, which occurs both in 276
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South America and in Africa, produced the pollen grains, and this would indicate migration across the Atlantic Ocean in Early Eocene times. BOMBACACEAE
Bombax ceiba type (Bombacacidites annae) The first occurrence of the genus Bombax can be dated as Paleocene in the Carribbean area. No ancestral types are known, however, and the rather sharp lower limit of occurrence suggests immigration from elsewhere. In Nigeria similar, but not identical, pollen types are known from the Paleocene-Eocene transition onwards. In the Caribbean area the Bombax ceiba type becomes rare during the Eocene and has given rise to a host of related types which cannot be discussed here because of their limited stratigraphical interest.
Catostemma (Jandufouria seamrogiformis) The very characteristic Catostemma pollen grains are not found below the Upper Eocene in the Caribbean area. They show strong local dominance especially in the Oligocene and Lower Miocene, which may be taken as an indicator of the presence of rain forest. The origin of this pollen type is not known, but related tricolporate pollen grains referable to the genus Aguiaria occur already in the Lower Eocene. CLUSIACEAE (GUTTIFERAE)
Symphonia globulifera type (Pachydermites diederixi) Symphonia globulifera occurs at present in coastal swamps of tropical Africa and South America and its pollen is highly characteristic. It is the only species of the genus with a relatively wide distribution, the other sixteen species being restricted to Madagascar, where they occur in a variety of habitats. In Nigeria there is clear evidence of first appearance in the Middle Eocene, but in the Caribbean area the first appearance is much later and can be fairly accurately dated as Early Miocene. It would appear reasonable, considering the concentration of endemic and mainly non-coastal species in Madagascar, to assume Africa and probably Madagascar to have been the centre of origin of the genus. At an unspecified time Symphonia globulifera managed to reach the west coast of Africa, arriving in Nigeria at the end of the Eocene and becoming rapidly a dominant species in the coastal vegetation. After a delay corresponding to not more than approx. 25 million years the species succeeded in crossing the Atlantic Ocean and reached the Rev. Palaeobotan.Palynol., 6 (1968) 189-348
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Caribbean area. The means by which this dispersal took place are as yet wholly obscure. At this late stage in the Tertiary the topography must have been similar to present-day conditions, and the chances of Symphonia seeds crossing the Atlantic must have been extremely small. That this nevertheless occurred can hardly be doubted, however, and the long time delay is a silent witness of the numerous unsuccessful attempts which must have preceded the final success. The fact that Symphonia globulifera grows in coastal swamps may have slightly increased its chances of long-distance seaborne dispersal. Similar problems are involved in other transatlantic distribution patterns, but the case of Symphonia has been discussed at length, since here the data are most reliable. LYTHRACEAE
Cuphea (Striasyncolpites zwaardi) The typical pollen grains of the genus Cuphea, which is restricted to America, first appear in the palynological record of the Caribbean area in the Middle Miocene, but no ancestral forms are known.
Crenea ( Verrutricolporites rotundiporis) In the Caribbean area Crenea pollen is first found in the Upper Eocene and is especially common in the Lower Miocene, associated with dominant Rhizophora pollen in coastal sediments. In Nigeria it first appears at the base of the Miocene and is fairly abundant during the Lower Miocene, also in a coastal environment, only to disappear from the stratigraphical record in the Middle Miocene. In the Caribbean area a decrease sets in at approximately the same time, but Crenea pollen remains present in small numbers up to the present day. The palynological data thus provide a fairly complete record of the history of the genus Crenea. Its origin must be sought in the Eocene of South America and it apparently succeeded in crossing the Atlantic Ocean, probably during the Oligocene. It then flourished for a short time on the western African coast in the same environment as in South America. The reasons for its disappearance from Africa and its almost simultaneous decrease in abundance in the Caribbean area are unknown. As in the case of Symphonia, the coastal habitat of Crenea no doubt was a principal factor which significantly increased the chances of dispersal. SONNERATIACEAE
Sonneratia The following types can be distinguished: (l) Ancestral types: (Florschuetzia 278
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trilobata, Florschuetzia semilobata); (2) Sonneratia caseolaris (Florschuetzia levipoli) ; (3) Sonneratia alba (FIorschuetzia meridionalis). The relations between the FIorschuetzia pollen types, which so far only have been found in Borneo, and recent Sonneratiaceae are shown on Fig.16. From this diagram it can be seen that FIorschuetzia trilobata ranges from probably Upper Eocene to Middle Miocene. In its morphology this pollen type shows affinity to certain lythraceous pollen types, notably Lagerstroemia, and it appears not unreasonable to postulate derivation from lythraceous stock during the Eocene. During the Lower Miocene Florschuetzia semilobata enters the stratigraphical record, which type, although transitional specimens are scarce, is assumed to have been derived from F. trilobata by a morphological change from a continuous tectum to a discontinuous one, resulting in a verrucate sculpture, equally distributed over the whole grain, This species has a rather more restricted distribution than F. trilobata and becomes extinct slightly earlier. It cannot be closely matched with the pollen of a living species of Sonneratiaceae or Lythraceae, although there is a certain resemblance with the pollen of Sonneratia gri~thii. Within a relatively short span of time after the appearance of Florschuetzia semilobata, a third related species is noticed, F. levipoli. Between these two pollen types transitions are rather common, with a gradual transition towards a concentration of the verrucate sculpture on the equatorial belt, the formation of tectatepsilate polar caps and the loss of the trilobate condition. Florschuetzia levipoli further shows a statistically significant increase in size during the Mio-Pliocene, and ultimately can be connected with the pollen of the Recent species Sonneratia caseolaris. Slightly later again, in Middle Miocene times, a further differentiation takes place and FIorschuetzia meridionalis makes its appearance, characterized by further modifications in the direction of a meridionally differentiated sculptural pattern, intra-areolate structure on the poles and, compared with F. levipoli, a further increase in size. Transitions with F. levipoli occur in the early part of its range. The youngest fossil specimens of Florschuetzia meridionalis are identical with pollen of the Recent species Sonneratia alba. The changing percentages of the Florschuetzia pollen types are shown on the graph, and are thought to reflect the degree of dominance in the coastal vegetation for each parent species. It would appear from this graph that the ancestral species Florschuetzia trilobata remains present in significant numbers after having given birth to the younger offshoots F. semilobata and F. levipoli. Its disappearance is distinctly gradual. It is not certain whether the parent plant of F. trilobata actually grew in the mangrove environment, but its abundance in Oligo-Miocene coastal sediments of the type in which later Sonneratia and Rhizophora pollen become dominant, strongly suggests this having been the case. The youngest offshoot of the Sonneratia complex proved to be Sonneratia Rev. Palaeobotan. Palynol., 6 (1968) 189-348
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alba, but whether this species originated from S. caseolaris or from the much rarer S. ovata, of which unfortunately no fossil record exists, must remain uncertain for the present. Also the relation to the Indian species S. apetala is unknown for lack of fossil evidence. In this connection it must be stressed that, although it is possible to arrange the pollen types described here in transitional sequence, starting from the simply built FIorschuetzia trilobata and ending with the complex Sonneratia alba pollen, this in itself does not constitute proof of phylogenetic relationship. The fact that this morphological sequence can be shown to have time-stratigraphical significance, the more complex pollen type being the youngest, of course argues for a phylogenetic relationship. However, the rather abrupt change between FIorschuetzia trilobata and F. semilobata is hard to visualize without a sudden change in genetic constitution of part of the F. trilobata population. Or, it may be that this change did not actually take place in northwestern Borneo but elsewhere, and that the newly evolved F. semilobata immigrated soon afterwards. The inferred gradual replacement of the unknown parent plant of the fossil FIorsehuetzia trilobata pollen species by the modern Sonneratia group might reflect ecological competition within the mangrove environment. The development of Sonneratia alba, on the other hand, can be seen as the later origin of a species which is, of all Sonneratia species, best adapted to the marine environment and thus represents a culmination of the evolutionary process. This holds good not only for the ecological adaptation of S. alba, but also for its pollen type, which is the most complex and largest of all Sonneratia pollen types. The large degree of variability in size and morphology observed in the pollen of the living populations of Sonneratia alba, caseolaris and ovata in different parts of their ranges, would indicate that the potentialities for further evolutionary change in pollen characters are by no means exhausted. However, it will be difficult to predict the course of future changes in the absence of any knowledge as to what is precisely the selective value of pollen characters. In particular the size increase in the course of the Neogene observed both in Sonneratia caseolaris and alba pollen deserves special attention in this respect. It has been stated by COVAS and SCHYACK (1945) that pollen size is related to length of style, but in the Sonneratiaceae this relation does not exist, since in the genus Duabanga the style is as long as in Sonneratia, while the pollen grains are much smaller. Nor are the size differences between pollen of Sonneratia alba, caseolaris and ovata correlated with any difference in length of style, which is approximately equal for all three species. With the scarce data available it would appear possible that the increase in pollen size is linked with the gradual physiological adaptation to the saline mangrove environment, since S. alba, which can stand the highest salinities, also has the largest pollen. It is further of interest that pollen fertility in the hybrid S. alba × ovata is higher than in S. alba × caseolaris (MULLER and Hou-L1u, 1966) indicating
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that S. alba is probably more closely related to S. ovata than to S. caseolaris. A further elucidation of these problems will have to be deferred until the discovery, probably in other areas, of fossil Sonneratia ovata, S. griffithii and S. apetala pollen. RHIZOPHORACEAE
Rhizophora type ( Zonocostites ramonae) Included in this type are the pollen grains of the genera Rhizophora, Bruguiera and Ceriops. Although differences in pollen type are known to exist between the genera and constituent species, it has proved impracticable to try to separate them on a routine basis. The following account therefore relates mainly to the history of the tribe Rhizophoreae, to which the genera mentioned belong and which are all mangroves. As far as known the Rhizophora pollen type is unique and cannot be confused with pollen from other taxa (cf. also MULLER, 1964). The fossil record in Borneo shows that the Rhizophora type is absent in Cretaceous and Paleocene sediments. It probably occurs first in Eocene sediments, but due to poor preservation this cannot yet be stated with certainty. In the Oligocene it is definitely present, but in small quantities only; it gradually increases in abundance to become in the Miocene-Pliocene the dominant element in the coastal microflora. In the Caribbean area it is definitely known for the first time in Upper Eocene sediments, being absent in older strata. Again it is only in the Miocene that Rhizophora reaches the high percentages so characteristic of the Neogene and Recent sediments of coastal or marine origin. In Nigeria, in contrast, it is definitely absent from pre-Miocene sediments and starts occurring rather suddenly in high percentages in the lowermost Miocene. If this fossil evidence is combined with the present-day distribution pattern of the tribe Rhizophoreae as discussed recently by VAN SVEENIS (1962a), the following tentative history can be reconstructed: (1) Origin of the tribe Rhizophoreae in the Eocene of southeastern Asia, since today the largest number of genera and species occur there, as well as inland relatives (Carallia, Anisophyllea). (2) Extension of the range of a few species of Rhizophora eastwards across the Pacific Ocean to tropical South America, reaching the Caribbean area via the gap in the Panama isthmus, most probably during the Eocene, followed by development of local species. (3) Crossing of the Atlantic Ocean in the Early Miocene and settling of the American species of Rhizophora on the west coast of Africa. (4) Extension of the range of the Indo-Malesian species of Rhizophora westwards to east Africa at an as yet undetermined time.
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VAN STEENIS (1962a) has concluded that the genus Rhizophora was unable to migrate along the southern tip of South Africa and along the southern shore of the Tethys sea, because of adverse climatic conditions, thus explaining the fact that the east and west African coasts have no Rhizophora species in common. For South Africa this has certainly been the case, but for the Tethys it would appear unlikely. Firstly, the Eocene Period was characterized, as already mentioned in the discussion on Nypa distribution, by an expansion of the tropical belt to higher latitudes and, even at its present location the southern Tethys shore could during this period have been favourable for the growth of Rhizophora. Secondly, it is generally assumed that the formation of the Alps was accompanied by a certain amount of crustal shortening during the considerable compression and overthrusting of the ancient Tethys sediments and therefore the Eocene southern shore could easily have been situated 100-200 km further southwards than its present-day location. It is, therefore, conceivable that the failure of the Indo-Malesian genera and species of Rhizophoreae to reach west Africa is due not so much to a cool climate along the Palaeogene Tethys shores but to the fact that these plants had not fully evolved yet. By the time they had developed the present species and had started to extend their range, i.e., in the Oligo-Miocene Period, the Tethys connection to the Atlantic Ocean had either already closed or was situated too far north in a cooler climatic zone. This alternative hypothesis has of course to be tested by studying the pollen content of the coastal sediments along the ancient Tethys shores. ACANTHACEAE
Justicia type (Multiareolites formosus) Although some of the genera which produce this pollen type have a pantropical distribution, the occurrences in the Neogene appear to be restricted to the Caribbean area and Nigeria. It is possible that the extension of the range to the Indo-Malesian area took place relatively late in the Mio-Pliocene.
Trichanthera type ( Multimarginites vanderhammeni) The genera which produce this pollen type are restricted at present to the American tropics and accordingly the fossil pollen type is known only from the Caribbean area. From the fact that acanthaceous pollen types are only known from the Neogene it might be inferred that this family is of relatively late origin.
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ASTERACEAE (COMPOSITAE) The following three Asteraceae pollen types have been distinguished: (l) Tubul([torae type (Echitricolporites spinosus); (2) Liguliflorae type (Fenestrites spinosus); and (3) Ambrosia type (Echitricolporites mcneillyi). Future detailed studies on well-preserved fossil material will no doubt lead to a further subdivision of these type groups. The Tubuliflorae type appears to be the oldest and the most widespread of the three Asteraceae pollen types. It has not yet been found with certainty in pre-Miocene sediments. In all three areas investigated the very gradual increase in abundance appears to be contemporaneous, but the high percentages reached in the Mio-Pliocene of the Caribbean area have not been found so far in Nigeria or Borneo. The Liguliflorae type is much rarer and has only been regularly observed in the Caribbean area, where it appears slightly later than the Tubuliflorae type. The Ambrosia type, only known from the Caribbean area, appears still later. Asteraceae are widespread in the present-day tropics, but are more common in open vegetation types, such as the savannah or higher montane vegetation than in the closed lowland rain forest. This largely explains the considerable quantities of Asteraceae pollen observed in the Caribbean area Mio-Pliocene in comparison with the relative scarcity in an area such as northwestern Borneo. Earlier views (KUvL et al., 1955) that, on the basis of the palynological record, Asteraceae emerge as one of the youngest developments within the angiosperms are thus confirmed. The place of origin is still obscure, however, and may very well have been situated outside the tropical belt, the time of origin presumably being mid-Tertiary. The relatively quick and simultaneous extension of the range of Asteraceae, especially of the Tubuliflorae type, as shown by the palynological data, probably reflects the efficient seed dispersal which characterizes the family.
SUMMARY OF BOTANICALRESULTS The above examples demonstrate, when an explanation of the stratigraphical distribution patterns is attempted, that a number of problems relating to origin, dispersal and extinction of plant taxa are involved. First of all it must be emphasized, that the data presented give direct evidence only on the development of pollen and spore characters. The first development of a combination of characters similar to that found in the pollen type of a recent taxon does not necessarily mean that all the other characters of flower, fruit and leaves, which define this taxon, also originated at the same time. However, the gradual transformation of a pollen type from an extinct form into one known from a Recent taxon may be taken to
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represent reasonable evidence for time and place of origin. On the other hand a sudden appearance of a new pollen type in the stratigraphical record of one area will in most cases be due to the presence of a stratigraphical hiatus or to immigration. So far only a general dating of first appearance has been possible for some taxa (e.g., Nypa, Ctenolophon, Asteraceae) but ancestral types mostly have not been found, signifying no doubt that the precise place of origin has not yet been sampled. Only in the case of Sonneratia evidence for continuity between an ancestral extinct pollen type and younger, still living offshoots was found. It is expected that future detailed studies of many more, continuous sections will bring to light more examples of this kind. Once the palynological record has registered the origin of a new taxon, it may also provide evidence for its dispersal by recording the extension of range in time and space. The most striking examples of this are represented by those cases where transatlantic migration has to be postulated (Symphonia, Crenea, Amanoa, Rhizophora, Malpighiaceae). The significance of these data can of course only be evaluated if reasonable estimates of dispersal probabilities and reliable palaeogeographic information are available. As regards the first point, transatlantic dispersal of the taxa involved under present-day conditions appears virtually impossible. Also geological evidence is not in favour of closer geographic connections between tropical Africa and South America in the Tertiary. It would, therefore, appear justified to regard the cases cited as indeed reflecting rare instances of long-distance dispersal of diaspores, illustrating SIMeSON'S (1952) opinion that, given enough time even the most unlikely events will occur. Nevertheless, at the same time, it must be stressed that a general exchange of floral elements between Africa and South America is definitely not visible in the Tertiary palynological record. The undoubted floristic affinities between these two areas, referred to by plant geographers from ENGLER (1905) onwards must date, therefore, from earlier periods. The palynological record also shows many examples of contraction of range, leading in extreme cases to extinction. It is generally impossible to pinpoint the causes, although in a general way climatological changes, which can be deduced from large-scale changes in the palynological record, must play an important part. Other contributory factors, which may well be responsible, are competition due to immigration or the evolution of new floral elements.
PLATE I 1. Foveotriletes margaritae (VAN DER HAMMEN) nov. comb., Colombia. 2. Foveotriletes margaritae (VAN DER HAMMEN) nov. comb., Venezuela. 3. Crassoretitriletes vanraadshooveni nov. gen., nov. sp., Nigeria, holotype. Magnification × 1,000.
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PLATE[
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SYSTEMATICALPART
Division I Sporites H. POTONIL 1893
Class A Triletes (REINSCH, 1881) POTONIE et KREMP, 1954 Genus Foveotriletes (VAN DER HAMMEN, 1954) ex R. POTONII~, 1956
Foveotriletes margaritae (VAN DER HAMMEN, 1954) nov. comb. (Plate I, 1, 2) Literature: Triletes margaritae VAN DER H AMMEN, 1954, p.102, pl.17. Remarks: The original short diagnosis is here enlarged. The identity of the specimens described by us has been confirmed by Van der Hammen. Description." Single grain, radially symmetrical, anisopolar with rounded distal pole and slightly pointed proximal pole, in polar view subangular; shape spherical-suboblate. Laesura trilete, relatively short (7-13/~), straight, sometimes inconspicuous. Foveolate; foveolae circular-oval, ~-2/~ wide, 1-2 ~t apart, exine 1-2 ~ thick. Dimensions: 44-56 # (equatorial diameter). Variability: In size and coarseness of sculpture. Comments: This species differs from Filtrotriletes nigeriensis VAN HOEKENKLINKENBERG, 1966 in its thinner wall and shorter, less pronounced laesura. Distribution: Lower part of the Proxapertites operculatus Zone in Nigeria and northern South America, decreasing in frequency in the upper part of the Retidiporites magdalenensis Zone. Extinct in younger zones. Taxonomic affinities: Unknown, although some similarity exists with published illustrations of Lindsaya orbiculata, Ophioglossum falcatum, O. concinnuum, and Botrychium subbiJbliatum, none of which was available for comparison. Genus Crassoretitriletes nov. gen.
Derivatio nominis: Name derived from the coarsely reticulate ornamentation. Diagnosis: Spherical, trilete, entirely coarsely reticulate with undulating muff; thick-walled, laesura indistinct. Type species: Crassoretitriletes vanraadshooveni nov. sp. The type material of the new species described below has been deposited at the Palynological Section, Botany Department, Municipal University, Amsterdam (The Netherlands). 286
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Crassoretitriletes vanraadshooveni nov. sp. (Plate I, 3; holotype) Derivatio nominis: Named in honour of Mr. B. van Raadshooven in recognition of his contribution to Venezuelan palynology. Holotype: Slide No. TC-151, well Egbema-l, 3015 ft., Nigeria. Description: Single grain, radially symmetrical, anisopolar, with rounded distal pole and slightly pointed proximal pole, in polar view almost circular. Laesura trilete, indistinct, often covered by sculpture. Reticulate over entire surface; muri undulating, 3-4/z wide, 2/z high, lumina 2-4/z wide, 6-12 /z long. Exine 14-2 # thick. Dimensions: 58-101 /~ (equatorial diameter). Variability: Moderately variable in size and in coarseness of sculpture. In Borneo a distinct variety has been observed in which the wall is finely perforated, but this is included in the species. Distribution: Pantropical approximately from the base of the Crassoretitri/etes vanraadshooveni Zone upwards, but disappearing in northern South America at the base of the Echitricolporites spinosus Zone. First appearance in Borneo slightly earlier than in the Caribbean area, in Nigeria even at the base of the Verrutricolporites rotundiporis Zone. Taxonomic affinities." Close correspondence virtually amounting to identity exists with Lygodium microphyllum (Plate II, 1) (~- Lygodium scandens). This is based on Recent material collected in Nigeria and Borneo. However, NAYARet al. (1964) have recently described the spore of Lygodium microphyllum as tuberculate distally and smooth proximally. Evidently a different species is involved and checking of the original herbarium sheets is necessary to resolve this discrepancy. Genus Cicatricosisporites POTON~ et GELLZTJCH, 1933
Cicatricosisporites dorogensis POTONII~et GELLETICH,1933 (Plate I1, 2) Literature: Cicatricosisporites dorogensis POTONI~et GEt LETICH, 1933, p.522, pl. 1, fig. 1-5. Striatriletes susannae VAN DZR HAMMEN, 1956d, p.l 15, fig.5. Description: Single grain, radially symmetrical, anisopolar, with rounded distal pole and pointed proximal pole; in polar view semi-angular to almost circular. Laesura trilete, short. Contact area of proximal face unsculptured, remainder of wall striate or striate-rugulate. Striae 1~-2 # high, ~--1/z wide; grooves between striae lz-2~/~ t l wide. Exine 1½-2/~ thick. Dimensions: 55-70 ~u (equatorial diameter). Variability: Moderately variable in size and ornamentation. Compared to Rev. Palaeobotan. Palynol., 6 (1968) 189-348
287
Cretaceous representatives of this species the variability is much less in our Tertiary material and the spores are certainly identical with the type as originally described by POTONI~ and GELLEVlCH(1933), and later on from the same locality by KDVES (1960, 1961). Distribution: In northern South America ranging from the base of the Verrucatosporites usmensis Zone to the lower part of the Magnastriatites howardi Zone (top Cicatricosisporites dorogensis Zone), higher occurring sporadically~ possibly reworked. In Nigeria ranging from slightly above the base of the Verrucatosporites usmensis Zone to approximately the same level in the Magnastriatites howardi Zone (top Cicatricosisporites dorogensis Zone). In Borneo virtually absent during the whole of the Tertiary. Taxonomic affinities: Similar spores are found in the genera Anemia and Mohria (Schizaeaceae). Genus Magnastriatites nov. gen.
Derivatio nominis: Name derived from the coarsely striate ornamentation. Diagnosis." Spherical, trilete, coarsely striate, except on the proximal contact area which is surrounded by a circular ridge. Striae continuous, grooves about as wide as ridges, size around 100 ~t. Type species: Magnastriatites howardi nov. sp. Comments." The genus differs from Cicatricosisporites in the relatively smaller number of coarser striae, the circular ridge surrounding the smooth proximal contact area and the much larger size. Magnastriatites howardi nov. sp. (Plate IIl, 1; holotype)
Derivatio nominis: Named in honour of Mr. E. A. Howard in recognition of his contribution to Trinidadian palynology. Holotype: Slide No. TC-152, well Dificil-1, 1300-1308 ft., Colombia. Description: Single grain, radially symmetrical, anisopolar, with rounded distal pole and more pointed proximal pole, in polar view nearly circular; shape suboblate-spherical. Laesura trilete, costate; costae 2 # wide. Contact area of
PLATE II 1. Lygodium microphyllum R. BROWN, Recent. 2. Cicatricosisporites dorogensis POTONII~ et GELL~TJCH, Nigeria. 3. Verrucatospor#es usmensis (VAn DER HAMMEN) nov. comb., Nigeria. 4. Stenoehlaena palustris BEDDOME, Recent. Magnification × 1,000. 288
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proximal face psilate, surrounded by a circular ridge, which makes contact with the striate ridge pattern at the points of the laesura. Remainder of wall coarsely striate; striae 1-2/~ high, 2-3½/z wide; grooves 1~-3 ~t wide. Exine 1~-2~ ~ it thick. Dimensions." 77 132/z (equatorial diameter). Variability: There is some variability in size and sculpture; thicker striae may occur in smaller number or much wider grooves. Also the proximal side of the grain may be locally perforated. Distribution: Regularly present from the base of the Magnastriatites howardi Zone upwards, in all three areas. Its first appearance is remarkably sudden and, as far as can be judged simultaneous. No ancestral forms are known. Taxonomic affinities." Virtually identical with the spores of the tropicalsubtropical fresh-water fern genus Ceratopteris (species seen: C. thalictroides, Plate IV, 1, and C. cornuta).
Class B Monoletes IBRAHIM, 1933 Genus Verrucatosporites (PFLuG, 1952)ex R. POTONI~, 1956 Comments: The spores described by VAN DER HAMMEN (1956d) under the genus Verrumonoletes clearly fall within the circumscription of Verrucatosporites and this name has priority. Verrucatosporites usmensis (VAN DER HAMMEN, 1956d) nov. comb. (Plate II, 3) Literature: Verrumonoletes usmensis VAN DER HAMMEN, 1956d, p.116, fig.7. Remarks: The paper cited above consists of a Spanish (VAN DER HA~MEN, 1956C) and translated English text (VAN DER HAMMEN, 1956d). In the former the species name is given as "usmensoides", in the latter as "usmensis". In agreement with Van der H a m m e n the name "usmensis" is taken as the correct one, referring also to Plate I, 7. Description: Single grain, bilaterally symmetrical, anisopolar, with convex distal outline and straight or slightly concave proximal outline; in polar view ellipsoidal. Laesura monolete. Geminate; gemmae 12-2~ ~ ~ # high and 17-2z ~ /z wide at base, rather widely and variably spaced. Exine thickness I ,u. P L A T E III 1. Magnastriatites howardi nov. gen., nov. sp., Colombia, holotype. 2. Grimsdalea magnaclavata nov. gen., nov. sp, Trinidad, holotype. 3. Monoporites annulatus VAN DER HAMMEN,Venezuela. Magnification × 1,000. 290
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Dimensions: 39-61 /t, including gemmae. Variability: In size and coarseness of sculpture. Comments: The species most probably has evolved from a verrucate ancestral type, since transitions are common at the base of its range in Venezuela. Distribution: First regular occurrence marks the base of the Verrucatosporites usmensis Zone. In northern South America the species then remains present throughout the Tertiary, but in Nigeria a sharp decline occurs at the base of the Verrutricolporites rotundiporis Zone. In Borneo the species remains very common up to the Recent. Taxonomic affinities." Although a verrucate sculpture is very common among fern spores of varied taxonomic affinities, a geminate sculpture in which the gemmae are separated from each other is much rarer and has so far only been found in Stenochlaena palustris, an Indo-Malesian climbing fern (Plate I1, 4). It is, however, possible that other members of this genus show the same pollen type, since only a restricted number of species was available for comparison. Spores which show a transition between verrucate and geminate are produced by Phlebodium aureum and Histiopteris incisa.
Division II Pollenites R. POTONII~, 1931
Class lnaperturatae IVERSEN et TROELS SMITH, 1950 Genus Grimsdalea nov. gen.
Derivatio nominis." The genus has been named in memory of the late Dr. T. F. Grimsdale, who launched the idea of applying palynology in oil exploration in 1937. Type species." Grimsdalea magnaclavata nov. sp. Diagnosis: Spherical, aperture indistinct or absent, wall thin, intectate, sculpture of two types, finely scabrate and coarsely clavate. Grimsdalea magnaclavata nov. sp. (Plate II1, 2; holotype)
PLATE IV
1. Ceratopteris thalictroides BRONGNIART,Recent. 2. Spinizonocolpitesbaculatus MULLER,Venezuela. 3. Spinizonocolpitesechinatus MULLER,Venezuela. Magnification × 1,000. 292
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PLATE IV
2 Rev. Palaeobotan. Palynol., 6 (1968) 189-348
293
Derivatio nominis: Name derived from the clavate ornamentation. Holotype: Slide No. TC-153, well Fe-100, 2365 ft., Trinidad. Description: Single grain, possibly bilaterally symmetrical, isopolar, almost spherical. Aperture absent or indistinct. Wall intectate, densely covered with a finely baculate-scabrate sculpture as well as with scattered large clavae. Clavae 8-10 # apart, 7-10 # long, 22!-3/~ thick, sunken into locally thickened endexine with a conical base. Endexine 1 #, but underneath clavae 2-2½ /~ thick. Columellae ½ # thick and long. Dimensions: 40-62 # (excluding of clavae). Variability." Some variability in size and wall thickness occurs. Distribution." Restricted to the Caribbean area where it occurs from the base of the Grimsdalea magnaclavata Zone upwards to the lower part of the Alnipollenites verus Zone, where it apparently becomes extinct. Taxonomic affinities: Unknown, possibly derived from an extinct palm species. Class Monoporatae IVERSENet TROELSSMI]'H, 1950 Genus Monoporites (CooKSON, 1947) ex VAN DER HAMMEN, 1954
Monoporites annulatus VAN DER HAMMEN, 1954 (Plate III, 3) Literature." Monoporites annulatus VAN DER HAMMEN, 1954, p.90, pl.6, fig.4. Monoporites unipertusus VAN DER HAMMEN, 1956b, p.82, pl.5, fig.10.
Description." Single grain, radially symmetrical, anisopolar, almost spherical. Single aperture small, circular, penetrating entire wall, costate; costa 4~-/~ wide, slightly protruding. Endexine < ¼/~ thick; columellae indistinct <: ¼/~ long and thick; tectum < ¼ # thick, psilate-very finely perforate or scabrate. Dimensions." 38-43/~. Variability: Considerable variability in size of grain and pore exists, but the wall is always rather thin. The surface of the wall is mostly smooth but a finely scabrate surface occurs occasionally. Since it is mostly unknown whether this condition is due to corrosion or not, this sculpture type is included. Distribution: In the Caribbean area and in Nigeria occurring regularly from the base of the Monoporites annulatus Zone upwards, although with rather pronounced fluctuations in numbers and generally more abundant in the Neogene than in the Palaeogene. Rare occurrences below the base of the Monoporites annulatus Zone are known. In Borneo base not yet determined, but absent in Paleocene and Upper Cretaceous. The significance of the fluctuations of grass pollen has been discussed in the section "Botanical results". 294
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
Taxonomic affinities: The fossil species closely resembles non-cultivated Poaceae (Gramineae) pollen. Since the type is produced by many different genera, further identification is not possible at present.
Class Monocolpatae IVERSEN et TROELS SMITtt, 1950 Genus Spinizonocolpites MULLER, 1968
Spinizonocolpites echinatus group (Plate IV, 2, 3)
Literature: Spinizonocolpites echinatus MULLER, 1968. Spinizonocolpites baculatus MULLER, 1968. Remarks: The distinction made by Muller between an echinate and a baculate form was not made in all areas and consequently for the present review the two species have to be grouped together. Description: Single grain, radially symmetrical, slightly anisopolar, since the grains are separated by a continuous equatorial colpus into two slightly unequal parts; suboblate-spherical. Colpus ectexinous, somewhat irregularly bordered, with a narrow indistinct margin of thinning ectexine. Total wall thickness about 1½/~; endexine ½ # thick, columellae < 1 /~ long, < ½/~ thick, covered by a thin, finely reticulate tectum; lumina < 1 /~, muri ½ # wide and thick. Spines scattered on tectum, 5-13 # long, 10-12/~ apart, either echinate, conical with a rather blunt to pointed apex and with the lower part often slightly expanded (Sp. echinatus) or baculate with rounded or slightly pointed tips, straight or slightly curved (Sp.
baculatus). Dimensions: 30-62/~. Variability: The two species grouped here together are in general rather distinct, but transitional specimens do occur occasionally. In both there is some variability in thickness of wall and coarseness of reticulation. Distribution: Occurs throughout Upper Cretaceous and Palaeogene of all three areas, but disappears from the record in the Caribbean area approximately in the higher part of the Verrucatosporites usmensis Zone. In Nigeria the species disappears slightly higher since it occurs in the whole of the Verrucatosporites usmensis Zone. In Borneo present up to the Recent. In Upper Cretaceous-Paleocene sediments of all three areas, Sp. baculatus is the dominant form, while later Sp. echinatus is found exclusively. This distribution together with the occurrence of transitional forms suggest a phylogenetic connection. Taxonomic affinities: The echinate form is identical with pollen of Nypa fruticans (Arecaceae or Palmae, Plate V, 1) and cannot be confused with any other pollen type known at present. The baculate form is not matched yet, and probably
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
295
represents an extinct ancestral form. Nypafruticans is at present restricted to the mangrove environment of the humid Indo-Malesian tropics, from the Ganges delta to northern Australia. Genus Proxapertites VAN DER HAMMEN, 1956c
Proxapertites operculatus (VAN DER
HAMMEN,
1956c)
(Plate V, 2)
Literature: Monocolpites operculatus VAN DER HAMMEN, 1954, p.89, pl.5, fig.2-3.
Proxapertites operculatus VAN
DER HAMMEN, 1956c, p.105, pl.l,
fig.3.
Description." Single grain, radially symmetrical, slightly anisopola~', since the grains ,-,re separated by a continuous equatorial colpus into two slightly unequal parts; oblate, in polar view rounded angular to oval; colpus ectexinous, somewhat irregularly bordered by a narrow, indistinct margin of thinning ectexine. Total wall thickness 1-2/z; endexine < 1 /z thick; columellae indistinct, -: I ,u long, ~ ½ # thick, covered by a <: 1 /z thick finely reticulate-perforate tectum; lumina 1 # wide, smaller along margin of colpus, muri ½ it wide, < 1 ,u high. Dimensions: 35-61 kt. Variability." In size and shape. Comments: The grains are here described as monads, while Van der Hammen suggests that they are dyads with the apertural faces touching. For a full discussion of this question see MULLER (1968). The species differs from the closely related Proxapertites cursus by its finer sculptural pattern, its generally isodiametrical lumina and the finer columellae which are more circular in cross-section. Distribution: Regularly present in the Proxapertites operculatus Zone in all three areas, but apparently appearing in Nigeria later than in the Caribbean area. In the younger zones the distribution is also different. In the Caribbean area decreasing in number in the Monoporites anmdatus Zone, but irregularly present also in much younger zones. In Nigeria its greatest abundance appears to fall in
PLATE V 1. 2. 3. 4. 5. 6. 7.
Nypa fruticans THUNBERG, Recent. Proxapertites operculatus (VAN DER HAMMEN), Colombia. Proxapertites cursus VAN HOEKEN-KLINKENBER6, Nigeria. Longaoertites vaneendenburgi nov. sp., Venezuela, holotype. Psiladiporites minimus VAN DER HAMMENet WYMSTRA,Trinidad. Sorocea ilicifolia MIQUEL, Recent. Retidiporites rnagdalenensis VAN DER HAMMENet GARCIA, Venezuela.
Magnification × 1,000.
296
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
~J
'~i,~iii~i~!~i~i~~ ~ ~~~ ~ ~i~~ ~
~
the Monoporites annulatus Zone; it is thereafter irregularly present, except in the youngest zones. In Borneo only known from the Proxapertites opereulatus Zone and probably disappearing from the stratigraphical record earlier than in the other two areas. Taxonomic affinities: In our opinion not derived from Astroca~3,um as suggested by VAN DER HAMMEN (1956C), but from an extinct group of palms related to Nypa (ref. MULLER, 1968).
Proxapertites cursus VAN HOEKEN-KLINKENBERG, 1966 (Plate V, 3)
Literature: Proxapertites cursus VAN HOEKEN-KLINKENBERG, 1966, p.43, pl.Ill, fig.2.
Description: Single grain, radially symmetrical, slightly anisopolar, since the grains are separated by a continuous equatorial colpus into two, slightly unequal parts; oblate, in polar view oval; colpus ectexinous, somewhat irregularly bordered by narrow, indistinct margins of thinning ectexine. Total wall thickness 2-4 /~; endexine 1 # thick; columellae rather distinct, straight, 1-2 ~ long, round to oval in cross-section, 1 /~ thick, covered by a l kt thick reticulate tectum; muri flat to rounded, 1-1½ /~ wide, 1 /t high, lumina up to 2 ,u in diameter, variable in size and shape, generally elongated oval or curved. Dimensions: 35-69/~. Variability: Rather variable in coarseness of wall structure, but attempts to split the type into smaller units according to the coarseness of the reticulum have been fruitless. Comments: As with the preceding species, in disagreement with its author, the grains are here described as monads. Differs from Proxapertites operculatus mainly in coarser reticulum with oval muri and distinct columellae. Distribution: Regularly occurring in the upper part of the Proxapertites operculatus Zone of all three areas, but base and top are strikingly different. In the Caribbean area starting at the base of the Ctenolophonidites lisamae Zone and disappearing from the record in the uppermost part of the Retibrevitricolpites triangulatus Zone. In Nigeria the first occurrences are in the lowermost part of this zone and the species is ranging upwards into the uppermost part of the Verrucatosporites usmensis Zone. In Borneo base and top occurrences are not exactly known yet, but the species is absent in younger zones. Taxonomic affinities: Clearly related to Proxapertites opereulatus and, therefore, affinities with Nypa also likely. Genus Longapertites VAN HOEKEN-KLINKENBERG, 1964
Longapertites vaneendenburgi nov. sp. (Plate V, 4; holotype) 298
Rev. Palaeobotan. Palynol., 6 (I 968) [ 89-348
Derivatio nominis: Named in honour of Mr. D. van Eendenburg in recognition of his contribution to Bornean and Trinidadian palynology. Holotype: Slide TC-154, well VLE-415, 13998-14037 ft., Venezuela. Description: Single grains, bilaterally symmetrical, anisopolar, the distal side arched and provided with a long colpus, the proximal side flat or slightly convex; in polar and in equatorial view oval. Colpus ectexinous, wide, slightly intruding, extending over about 2/3 of the greatest circumference of the grain. Wall thin, < 1 #; columellae only visible in central part near colpus, almost ½/z long, ¼ ~ thick; tectum evenly and finely perforate; muri ~/z, lumina ½ # in width. Dimensions: 59-83 ,u. Variability: Rather uniform in appearance. Comments: The species differs from Longapertites marginatus VAN HOEKENKLINKENBERG in the absence of a coarser reticulate pattern on the proximal side, and from Longapertites proxapertioides VAN DER HAMMENet GARCIA in the finely perforate wall, with lumen size <~ 1 /z. Distribution: In the Caribbean area restricted to the Foveotrico/pites margaritae and the Retidiporites magdalenensis Zone, but in Nigeria already present in the Proteacidites dehaani Zone and disappearing in the lower part of the Retidiporites magdalenensis Zone. Taxonomic affinities: The grain is probably derived from a palm species, but no distinct affinities can be listed. The wall structure of Pritchardia kamapuaana is rather similar, but the colpus is much shorter here. An arched colpus of the Longapertites type on the other hand is found in the genus Eugeissona, but here the wall structure is different.
Class Diporatae |VERSEN et TROELS SMITH, 1950 Genus Psiladiporites VARMA et RAWAT, 1963
Psiladiporites minimus VAN DER HAMMEN et WVMSTRA, 1964 (Plate V, 5)
Literature: Psiladiporites minimus VAN DER HAMMEN et WYMSTRA,1964, p.233, pl.I, fig.10.
Description: Single grain, radially symmetrical, isopolar, oval in equatorial and polar outline; diporate, pores penetrating both ectexine and endexine, 3-5 # wide, simple. Wall -~-/zthick, without distinct layers, psilate or very finely perforate. Dimensions: 13-21 #. Variability: Mainly in size and width of pores. Distribution: In the Caribbean area not found below the Verrutricolporites rotundiporis Zone with a distinct concentration in the Psiladiporites minimus Zone. Rev. Palaeobotan. Palynol., 6 (1968) 189-348
299
In Nigeria not observed, in Borneo mainly concentrated in the Eehitricolporites spinosus Zone. Taxonomic affinities: The genera Artocarpus, Ficus, and Sorocea (Plate V, 6, Moraceae) have very similar pollen and the fossil species is likely to have been derived from several genera of Moraceae, but there is little likelihood of further identification, since the differences between the genera in this family are small. Genus Retidiporites VARMA et RAWAT, 1963
Retidiporites magdalenensis VAN DER HAMMEN et GARCIA, 1966 (Plate V, 7) Literature: Retidiporites magdalenensis VAN OER HAMMEN et GARCIA, 1966, p. 109, fig.9. Description: Single grain, radially symmetrical, isopolar, oval in equatorial and polar outline; diporate, pores penetrating both ectexine and endexine, circular, 6-13/z wide, simple. Endexine 1- < ½ # thick; columellae ½-~i ½/~ long, < ½ ,u thick; tectum ½ - < ½ # thick, evenly reticulate-perforate, occasionally slightly finer near pores; lumina < -~-2/t wide, muri - ~-1½ ~t wide. Dimensions." 24-51 /z. Variability: Larger grains generally show a coarser ornamentation. Comments." Retidiporites bengalensis described by VARMA and RAWAT (1963) shows some similarity, but differs in possessing an endexine twice as thick as the ectexine. Distribution: Both in the Caribbean area and Nigeria regularly occurring in the Proxapertites operculatus Zone, but in the former area extending some distance in the Monoporites annulatus Zone, in the latter disappearing at the top of the Retidiporites magdalenensis Zone. Unknown from Borneo. Taxonomic affinities: Obscure, although some superficial resemblance exists with Banksia collina and Dryandra hmgifolia (Proteaceae).
PLATE VI
1. Multiareolitesformosus (VAN DER HAMMEN)nov, comb., Venezuela, upper focus. 2. Multiareolitesformosus (VAN DER HAMMEN)nov. comb., Venezuela, lower focus. 3. Dianthera americana LINNAEUS, upper focus, Recent. 4. Dianthera americana LINNAEUS, lower focus, Recent. 5. Multimarginites vanderhammeni nov. sp., Venezuela, holotype, upper focus. 6. Multimarginites vanderhammeni nov. sp., Venezuela, holotype, lower focus. 7. Trichantheragigantea HUMBOLDTet BONPLAND,upper focus, Recent. Magnification × 1,000. 300
Rev. Palaeobotan. Palynol., 6 (1968) 189 348
~!~,~
~~,¢:
~
~
~ ~'
I;i,~t/~
~
~
~s!~¢~111
Class Dicolporatae new class
Diagnosis: Pollen grains with two ectexinous colpi combined with two endexinous pores. Genus Multiareolites nov. gen.
Derivatio nominis: Name derived from circular areas of thickened ectexine. Diagnosis: Prolate, in polar view oval, dicolporate, colpi ectexinous, meridional, intersubangular, pores endexinous. Ectexine thickened on intercolpate areas and in rows of circular areas, 2-4/~ in diameter, bordering the colpi, columellae coarser in thickened areas. Type species." Multiareolites formosus ex VAN DER HAMMEN, 1956b. Comments: Van der Hammen has described the species Dicolporites Jormosus nov. gen. nov. sp. with a pollen grain derived from a Recent plant as type. Because this procedure is invalid according to the International Code of Botanical Nomenclature and because he has not since described a fossil grain of this type, the opportunity is taken to create a new genus for this pollen type, in order to do justice to its peculiar morphology. As genotype the fossil representative of Van der Hammen's original species is chosen and its name adopted. The genus name Dicolporites has been elevated in taxonomic rank and used to name the class Dicolporatae. Multiareolitesformosus (VAN DER HAMMEN, 1956b) nov. comb. (Plate VI, 1, 2) Literature: Dicolporites formosus VAN DER HAMMEN, 1956b, p.85, pl.6, fig.16.
Description: Single grain, radially symmetrical, isopolar, prolate, in polar view oval with colpi intersubangular. Dicolporate, colpi ectexinous, narrow with straight borders and pointed ends, pori indistinct, probably endexinous. Endexine < ½/~ thick, ectexine thickened on intercolpate areas and in single or double rows of circular "areoli", 2-4 # in diameter; columellae straight, sometimes slightly branched, longer and much coarser in areas where endexine is thickened, 2 ,u long on intercolpate areas and areoli, shorter on poles and along colpi, slightly irregular in outline and up to 1/~ thick on intercolpate areas, fine and probably isodiametric on rest of grain. Tectum ½ # thick, smooth or finely verrucate due to protruding columellae, probably finely perforate. Dimensions: 28-38/~. Variability: Smaller grains show a single row of areoli, while larger ones generally bear double rows. There is in addition variation in the distribution of areas with longer and coarser columellae and in the presence or absence of distinct 302
Rev. Palaeobotan. PalynoL, 6 (1968) 189-348
pores. The material did not permit a further separation and in the counting of samples all these variations have been grouped under the variable species Multiareolites formosus. Distribution: In the Caribbean area and Nigeria restricted to the Echitricolporites spinosus Zone. Not observed in Borneo. Taxonomic affinities: This very characteristic pollen type has only been observed in the following genera of the Acanthaceae: Adhatoda, Anisotus, Beloperone, Dianthera, Jacobinia, Justicia, Kolobochilus, Monechma, and Rungia. Justicia americana and Dianthera americana (Plate VI, 3, 4) come very close to the fossil grains, but it is of course not possible to be sure just which genera or species are represented. Genus Multimarginatus nov. gen.
Diagnosis: Spherical, di- or tricolporate; colpi long, multimarginate, in dicolporate grains crossing perpendicular (90 ° rotated bilaterally symmetrical), in tricolporate grains colpi always normally orientated; wall thick, tectum perforate or foveolate-fossulate. Type species: Multimarginites vanderhammeni nov. sp. Multimarginites vanderhammeni nov. sp. (Plate VI, 5, 6; holotype) Derivatio nominis: Named in honour of Dr. Th. van der Hammen in recognition of his contributions to South American palynology. Holotype: Slide TC-155, well Hervidero-l, 2770 ft., Venezuela. Description: Single grain, 90 ° rotated bilaterally symmetrical, isopolar, spherical; dicolporate; colpi very long, ectexinous, bordered by 3-4 strips, 4-5/z wide, perpendicularly orientated, straight borders and pointed or rounded ends; pori endexinous, transversely elongated, 4/z wide, 13 # long, constricted in the middle, costate; costae strongly protruding, 1½-2/~ thick. Endexine < 1 /z thick; columellae 1 # long, ½/z thick, tectum 2/z thick, foveolate, lumina I~-2 # wide, muri 2-3/z thick. Dimensions: 40-53/~. Variability: In size and coarseness of sculpture. Distribution: Only known from the Caribbean area where it occurs from the base of the Retitriletes vanraadshooveni Zone upwards. Taxonomic affinities: Close resemblance exists with Sanchezia klugii and Trichanthera gigantea (Plate VI, 7; Plate VII, 1). The latter grain, however, has a considerably larger size (105 #!). Other multimarginate species of Acanthaceae available are non-rotated symmetrical (Asteracantha longiJblia, Asystasia vogeliana, M imulopsis solmsii). Rev. Palaeobotan.Palynol., 6 (1968) 189-348
303
Class Triporatae IVERSENet TROELS SMITH, 1950 Genus Florschuetzia nov. gen. Derivatio nominis: The genus has been named in memory of the late Prof. Dr. F. Florschfitz, the founder of palynology in The Netherlands. Diagnosis: Subprolate, sometimes trilobate and with meridional ridges. Pores equatorial, circular, distinct. Wall tectate, columellae generally indistinct, sometimes fused. Tectum continuous, smooth or broken up into separate verrucae and differentiated in polar and/or meridional direction. Type species: F/orschuetzia tri/obata nov. sp. Comments: The genus differs from Verrutrico/porites VAN DER HAMMEN in the absence of colpi, the indistinctly columellate structure and the absence of a supratectate verrucate sculpture. The diagnosis has been taken wide enough to include the fossil sonneratioid pollen types, including the presumed ancestral one. Some confusion may, however, be possible with a "sporotype" described in 1954 by COOKSON and PIKE and named Santa/umidites, the description of which has subsequently been emended and accepted as a valid form genus by POTONI~(1960). In both Cookson and Pike's and Potoni6's diagnosis it is clearly stated that the maximum thickness of the wall is around the pores, as is the case in Santa/urn pollen. No confusion with Florschuetzia appears likely, therefore, and the genus would not have to be mentioned here, but for the fact noted before (MULLER, 1964) that the photomicrographs accompanying Cookson and Pike's paper strongly suggest that fossil pollen of Sonneratia caseo/aris has been included in S a n t a & m # dites (see especially their fig. 71, pl. 2, which is strikingly similar to F/orschuetzia levipoli). This suspicion is strengthened by Cookson and Pike's discussion of the affinities of Santalumidites cainozoicus in which the authors mention puzzling differences with recent Santalum pollen and a large degree of variability as well. If this would indeed prove to be the case, there would have been no choice left, other than correcting Cookson and Pike's description of the type and accepting
P L A T E VII 1. Trichanthera gigantea HUMBOLDTet BONPLAND,lower focus, Recent. 2. Florschuetzia trilobata nov. gen., nov. sp., Borneo, holotype. 3. Florschuetzia trilobata nov. gen., nov. sp., Borneo. 4. Florschuetzia trilobata nov. gen., nov. sp., Borneo. 5. Lagerstroemia speciosa (LINNAEUS)PERSOON,Recent. 6. Florschuetzia semilobata nov. gen., nov. sp., Borneo. holotype. 7. Florschuetzia semilobata nov. gen., nov, sp., Borneo. 8. Florschuetzia semilobata nov. gen., nov. sp., Borneo. 9. Florschuetzia levipoli nov. gen., nov. sp., Borneo. Magnification × 1,000.
304
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
'i~i~
~!,i~i! ~i~,!i!~,i',i~,i,~i!~.,'~ ~
ii~i!!i~!Ui~ ¸¸
,,,~,,
that Santalumidites had priority above Florschuetzia. However, since no type specimen has been preserved, nor type locality been designated by Cookson and Pike, it is impossible to verify this assumption. The photomicrographs alone, on which no structural details can be observed are considered inadequate also for selection of a lectogenotype, the more so since some of the diagnostic characters of the genus are not visible on the pictures. In view of this it was decided to follow recommendation PB 6 F (p.56) of the International Code of Botanical Nomenclature, which advises not to apply names originally attached to inadequately described or figured specimens to well preserved material. Hence the new genus Florschuetzia is established.
Florschuetzia trilobata nov. sp. (Plate VII, 2; holotype; Plate VII, 3, 4) Derivatio nominis: Name derived from the trilobate shape. Holotype: Slide TC-156, surface sample Dz-4493, northwestern Borneo. Description: Single grain, radially symmetrical, isopolar; prolate; in polar view strongly lobate. Triporate, pores circular, 2-4/z in diameter, intersubangular, ectexinous + endexinous; rarely, pores are combined with ~: colpoid grooves, which may be flanked by relatively short secondary meridional thickenings. Total wall thickness 2-3 /z on poles and meridional ridges, ± 1 /z on porate fields; endexine 4- ½/t thick; columellae generally indistinct, ½-1/~ long; tectum psilate, not clearly differentiated from underlying columellae, 1-2 ,u thick on poles and meridional ridges, probably < 1 /z on porate fields. Dimensions: 28-35 ,u. Variability: In degree of wall thickening on meridional ridges and in the occasional presence of colpoid grooves with secondary meridional ridges. Distribution: Only known from Borneo, earliest occurrence in Oligocene sediments (probably Verrucatosporites usmensis Zone), very abundant in the Magnastriatites howardi and the Crassoretitriletes vanraadshooveni Zone, disappearing from the record early in the Echitriporites spinosus Zone. Remarks: The species is distinguished from the psilate variations of Verrutricolporites rotundiporis by its larger size, trilobate condition, thickened meridional ridges and the nearly massive wall in which generally only a faint columellate layer is visible. The species differs from Florschuetzia semilobata in the psilate wall and the often pronounced meridional ridges. Taxonomic affinities: In general shape and wall structure, the species shows resemblance to pollen of Lagerstroemia flos-regina (Lythraceae) from which it differs, however, in the absence of distinct colpi. Lagerstroemia indica shows a comparable general shape and aperture structure which consists of circular pores without distinct ectexinous colpi, but differs in the verrucate-areolate sculpture of the tectum. Lagerstroemia speciosa (Plate VII, 5) is also similar in pore and 306
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
wall structure and sculpture but is only weakly trilobate and has inconspicuous meridional ridges, while indistinct colpi are also present. Since there exists distinct affinity to the recent and fossil sonneratioid types it is considered more likely that Florschuetzia trilobata represents the extinct ancestor of the recent genus Sonneratia than that it is derived from a fossil Lagerstroemia species. FIorschuetzia semilobata nov. sp. (Plate VII, 6; holotype; Plate VII, 7, 8) Derivatio nominis: Name derived from the semilobate shape. Holotype: Slide TC-157, surface sample Dz-5007, northwestern Borneo. Description: Single grain, radially symmetrical, isopolar; prolate; in polar view lobate. Triporate, pores circular, 1-2 # in diameter, interlobate, endexinous (in less well preserved grains appearing as endexine + ectexine). Total wall thickness 1-2 # on poles and meridional ridges, probably < 1 # on porate fields; endexine -< ½/~ thick, columellae generally indistinct; tectum ± 1 # thick, areolateverrucate, coarser on meridional ridges, finer on porate fields, on poles often showing a transition to a psilate polar cap. Dimensions: 23-24/z. Variability: In size, coarseness and areal differentiation of sculpture. Some specimens show a rather evenly distributed sculpture while others show a differentiation along the meridional ridges or in poleward direction. Distribution: Virtually restricted to the uppermost part of the Magnastriatires howardi Zone and the Crassoretitriletes vanraadshooveni Zone in Borneo ( Florschuetzia levipoli Zone). Taxonomic affinities: The apertures and sculptural type clearly point to affinity with the pollen of Sonneratiaceae, but matching with a Recent species has not been possible. FIorschuetzia levipoli nov. sp. (Plate VII, 9; Plate VIII, 1; Plate VIII, 2; holotype) Literature: ?Santalumidites cainozoicus COOKSONet PIKE, 1954, p.209, pl.2, fig.71. Derivatio nominis: Name derived from the smooth polar caps. Holotype: Slide TC-158, surface sample Mq-ll91, northwestern Borneo. Description: Single grain, radially symmetrical, isopolar; prolate; in polar view circular to rounded triangular, sometimes bulging at equator. Triporate, pores circular, endexinous, in well preserved grains covered by thin ectexinous membrane, 2-8/z in diameter (depending on size grain). Total wall thickness ~z 2 #, generally thicker on poles than on equatorial area; endexine ~ 1/z thick; columellae mostly Rev. Palaeobotan. Palynol., 6 (1968) 189-348
307
indistinct, slightly enlarged (intra-areolate) on polar caps: tectum < 1 /~ thick, psilate on poles, broken up into a verrucate-areolate pattern on equatorial belt. Verrucae rounded-polygonal, of varying sizes, uniform height, regularly distributed. Dimensions: 30-50 /~ (averages) showing a distinct increase in size from older to younger strata. Variability: In thickness of tectum on poles and coarseness of verrucation on equatorial belt. The visibility of the columellate layer is mainly determined by the state of preservation. Occasionally the presence of a meridional ridge is suggested by folding of the grain but this feature is not structurally different from the remainder of the equatorial belt. Distribution: Regularly present in Borneo from the higher part of the Magnastriatites howardi Zone upwards (FIorschuetzia levipoli and F. meridionalis Zones). Remarks: The species is distinguished from Florschuetzia meridionalis by the absence of a structurally differentiated meridional ridge, the indistinct or even absent intra-areolate pattern on the polar caps and the generally smaller size. Compared to Florschuetzia semilobata, the psilate polar caps and circular or only weakly triangular shape in polar view are diagnostic. The relation between size and age will be discussed separately. Taxonomic affinities." Apart from the generally smaller mean size the species agrees in all essential characteristics with the pollen of Sonneratia caseolaris (Plate VIII, 3), a mangrove species at present growing in estuaries along the IndoMalesian coasts, Florsehuetzia meridionalis nov. sp. (Plate VIII, 4; holotype; Plate VIII, 5) Derivatio nominis: Name derived from the meridional orientation of the sculptural pattern. Holotype: Slide TC-159, surface sample Mq-1191, northwestern Borneo. Description: Single grain, radially symmetrical, isopolar; prolate; in polar view circular to rounded triangular. Triporate, pores circular, endexinous, in well
PLATE VIII 1. 2. 3. 4. 5. 6. 7.
Florschuetzia levipoli nov. gen., nov. sp., Borneo. Florsehuetzia levipoli nov. sen., nov. sp., Borneo, holotype. Sonneratia caseolaris (LINNAEUS) ENGLER, Recent. Florsehuetzia meridionalis nov. gen., nov. sp., Borneo, holotype. Florsehuetzia meridionalis nov. gen., nov. sp., Borneo. Sonneratia alba J. E. SMITH,Recent. Sonneratia alba J. E. SMITH, Recent.
Magnification × 1,000.
308
Rev. Palaeobotan. PalynoL, 6 (1968) 189-348
.
~
=iii=!=!=!!(iii=i ==
preserved grains covered by thin ectexinous membrane, 5-12/, in diameter. Total wall thickness ~: 3/~, generally thinner on porate fields; endexine < l #; columellae distinct on meridional ridge where thin, uniform and rather dense, on polar caps probably fused to form a typical intra-areolate pattern, not visible on porate fields. Tectum 1-1½ /, thick, psilate on polar caps, broken up into an areolatefossulate pattern on meridional ridges and into a verrucate pattern on porate fields. The meridional ridges are fairly sharply outlined against the porate fields, but merge gradually with the tectate-psilate polar caps. Dimensions: 35-60 # (averages) showing a distinct increase in size from older to younger strata. Variability: In thickness of tectum on poles and in coarseness of sculpture and structure. Distribution: Occurring in Borneo only, from the middle part of the Crassoretitriletes vanraadshooveni Zone upwards (FIorschuetzia meridionalis Zone). Remarks: The species is distinguished from Florschuetzia levipoli by the presence of a structurally differentiated meridional ridge and the distinct intraareolate structure of the polar caps and generally larger size. Taxonomic affinities: Apart from the generally smaller size of the Fossil assemblages, the species agrees in all essentials with the pollen ofSonneratia alba (Plate VIII, 6, 7), a mangrove species at present growing in estuaries along the Indo-Malesian, Indian and eastern African coastline. Genus Echitriporites VAN HOEKEN-KLINKENBERG, 1964
Echitriporites trianguliformis VAN HOZKEN-KLINKENBERG,1964 (Plate IX, 1, 2)
PLATE IX 1. Echitriporites trianguliformis VAN HOEKEN-KL1NKENBERG,Venezuela. 2. Echitriporites trianguliformis VAN HOEKEN-KLINKENBERG,Colombia. 3. Proteacidites dehaani nov. sp., Venezuela. 4. Proteacidites dehaani nov. sp., Colombia, holotype. 5. Guevina avellana MOLINA, upper focus, Recent. 6. Guevina avellana MOLINA, lower focus, Recent. 7, Lomatia ilicifolia R. BROWN, upper focus, Recent. 8. Lomatia ilicifolia R. BROWN, lower focus, Recent. 9. Anacolosidites cf. luteoides COOKSONet PIKE, New Guinea. 10. Anacolosidites cf. luteoides COOKSONet PIKE, Borneo. 11. Anacolosa frutescens BLUME, upper focus, Recent. 12. Anacolosa frutescens BLUME, lower focus, Recent. 13. Alnipollenites verus POTON1~, Borneo. 14. Alnus glutinosa (LINNAEUS)GAERTNER, upper focus, Recent. 15. Alnus glutinosa (LINNAEUS)GAERTNER, lower focus, Recent. Magnification × 1,000.
310
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
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Literature: Echitriporites trianguliformis VAN HO~KFN-KLINKEN~ERG,1964, p.218, pl.47, fig.7. Echitriporites trianguliformis BELSK¥, BOLTENHAGENet POTON~k, 1965, p.77, pl.13, fig. 22, 23. Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view semi-angular. Triporate, pores ectexinous and endexinous, circular, 2 # in diameter, costate, often slightly protruding. Endexine 4 1 /z , intectateechinate, echinae 1-2 ,u long, ~: 1 /z wide at base, conical or with rounded tops, 2/z apart. Dimensions: 21-30 #. Variability: Considerable variation exists in size and shape of the grain and in size and density of the spines. The more triangular grains with fewer and smaller spines are more common in the Upper Cretaceous of northern South America, whereas the more rounded grains with slightly more and larger spines are more common in the Eocene. However, since many transitional specimens occur, no specific distinction was possible. Distribution: Encountered in the Proxapertites operculatus Zone in all three areas, but rare in Borneo and soon disappearing. In the Caribbean area and Nigeria the species remains an important component of the Eocene microfloras which has great practical value for local correlations. In both areas it disappears from the record around the top of the Verrucatosporites usmensis Zone. Taxonomic affinities: Despite intensive search, no positive identification has been possible yet. This, and its gradual disappearance at the top of the Eocene suggest that the taxon producing the pollen grains is probably extinct. A superficial resemblance is shown by some Proteaceae (Embothrium, Garnieria, Persoonia, Telopea). Only Telopea oreades and Embothrium mucronatum were available for comparison but these species showed finely columellate-tectate pollen grains. Genus Proteacidites (COOKSON, 1950) ex COUPER, 1953
Proteacidites dehaani nov. sp. (Plate IX, 3; Plate IX, 4; holotype) Derivatio nominis: Named in honour of Mr. R. de Haan in recognition of his contribution to Venezuelan palynology. Holotype: Slide TC-160, surface sample E 1362, Colombia. Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view triangular. Triporate, pores ectexinous and endexinous, circular, 2~,/~ in diameter, costate. Total wall thickness ~ 1 ~t, endexine ½/z thick, columellae < ½ # thick and long; duplicolumellate, reticulate-foveolate tectum; muri -:~ ½/z high, ½/z wide, fiat topped; lumina 1-1½/z wide, of variable shape, coarser on interporate fields, finer on poles and around pori. 312
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
Dimensions: 32-36/~. Variability: Ornamentation varying from reticulate-foveolate to perforate. Constant are size and shape, pore structure and the coarser sculpture on the interporate areas and the species is well characterized by these features. A comparable but not identical type is known from the post-Eocene of western Venezuela. Comments: The species appears different from reticulate members of the genus described by COOKSON (1950), COUPER (1953) and HARRIS (1965) mainly because of size, straight sides and duplibaculate muri. It is rather similar to Proteacidites thalmanni ANDERSON, 1960, from which it differs, however, in its larger size, absence of "notched" pores and presence of duplicolumellate muri. Distribution: In the Caribbean area and in Nigeria restricted to the lower part of the Proxapertites operculatus Zone and principal marker for the Proteacidites dehaani Zone. Taxonomic affinities: Close resemblance exists with pollen of Guevina avellana (Proteaceae, Chili, Plate IX, 5, 6). Other Proteaceae are more or less different: Lomatia ilicifolia (Chili, Australia, Plate IX, 7, 8) has smaller lumina, Cardwellia sublimis (Queensland) differs in its more rounded, non-costate pores. Stenocarpus sinuatus (Australia) is less distinctly multicolumellate and has a much thicker wall, Leucospermum hypophyllum (southern Africa) has smaller lumina and Symphionema montanum (Australia) has a much smaller size.
Class Stephanoporatae IVERSENet TROELSSMITH, 1950 Genus Anacolosidites (CooKSON et PIKE, 1954) ex R. POTONI~, 1960 Anacolosidites cf. luteoides COOKSON et P1KE, 1954 (Plate IX, 9, 10) Literature: cf. Anacolosidites luteoides COOKSON et P~KE, 1954, p.207, pl.1, fig.47-50. Description: Single grain, radially symmetrical, isopolar, oblate; subtriangular outline in polar view; pores arranged in two groups of three, opposite each other, each at a distance of :L 3 # from the equator, probably ectexinous and endexinous, 4½ /~ in diameter, equatorially elongated with slightly thickened borders; endexine ½ # thick at angles, up to 2/t thick at straight sides of equator; columellae simple, < 1 /~ thick at angles, 1 ,u thick at straight sides of equator; tectum uniformly < ½ # thick, psilate. Dimensions: 18-33 ,u. Variability: In size and wall thickness. Comments: It would seem that Cookson and Pike's species A. luteoides comes closest to the specimens described here and this name is adopted provisionally, pending further study. Rev. Palaeobotan. Palynol., 6 (1968) 189-348
313
Distribution: In Borneo and Nigeria already recorded from the Paleocene part of the Proxapertites operculatus Zone, but in the Caribbean area appearing later at the base of the Retibrevitricolpites triangulatus Zone (base Eocene). In the Caribbean area the species disappears from the record already at the top of the Retitricolporites guianensis Zone, in Nigeria it is found higher, up to the youngest part of the Magnastriatites howardi Zone, while in Borneo it remains common throughout the Tertiary. Taxonomic affinities: Close correspondence exists with pollen grains of Anacolosa (Plate IX, 11, 12), Cathedra and Ptychopetalum (Olacaceae). Genus Alnipollenites R. POTONI~, 1931
A&ipollenites verus (R. POTONI~, 1931) ex R. POTONI~, 1934 (Plate IX, 13) Literature." AInipollenites verus R. POTONII~, 1934, p.58, pl.2, fig. 17. Stephanoporitesfornicatus VAN DER HAMMEN, 1956b, p.94, pl.10, fig.3Y
Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view subangular. 3-6 ectexinous and endexinous pores, 3-4 # wide, slightly vestibulate; pores connected by arci; endexine <:~ 1 # thick, ectexine 1 /z thick, columellae indistinct, tectum smooth or finely granulate. Dimensions: 28-31 /~. Variability: The pore number is the main variable, five being the average. Distribution." In the Caribbean area occurring from the base of the Alnipollenites verus Zone upwards. In Borneo present from the upper part of the Verrucatosporites usmensis Zone to the top of the Crassoretitriletes vanraadshooveni Zone (MULLER, 1966). Taxonomic affinities: Close correspondence exists with Alnus pollen (Plate IX, 14, 15). Genus Pachydermites nov. gen.
Derivatio nominis: Name derived from the thick exine. Diagnosis: Stephanoporate grains with 4-6 rather irregularly shaped aper-
PLATE X 1. Echiperiporites estelae nov. sp., Borneo, holotype. 2. Pachydermites diederixi nov. gen., nov. sp., Nigeria, holotype. 3. Symphonia globtdifera LINNAEUS (ill.), Recent.
Magnification × 1,000.
314
Re v. Palaeobotan. Palynol., 6 (1968) 189-348
PLATE X
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
315
tures, which are larger in the endexine than in the ectexine, a very thick endexine, which is finely perforated around apertures and a thin tectate-psilate ectexine. Type species: Pachydermites diederixi nov. sp. Pachydermites diederixi nov. sp. (Plate X, 2; holotype) Derivatio nominis: Named in honour of Mr. D. O. J. Diederix in recognition of his contributions to Colombian and Nigerian palynology. Holotype: Slide TC-161, well Ughelli-3, 5200 ft., Nigeria. Description: Single grain, radially symmetrical, isopolar, oblate-suboblate. 4-6 porate, ectexinous apertures 6-10 /~ long, 4-9 /~ wide, almost circular and irregular in outline, endexinous apertures of identical shape, but slightly larger and somewhat vestibulate. Endexine 3-6 # thick, irregularly perforated around apertures. Interior surface irregularly verrucate; columellae ½/~ thick and long; tectum ½ # thick, psilate. Dimensions: 46-68/~. Variability: In size and coarseness of wall. Distribution: In Nigeria known from the base of the Monoporites annulatus Zone upwards, but in Venezuela occurring only from the base of the Grimsdalea magnaclavata Zone up wards. Taxonomic affinities." Identical with the pollen of Symphonia globulifera (Guttiferae, Plate X, 3). As far as known this pollen type does not occur in other genera and the identification has a very high degree of probability. Unfortunately the pollen of the Madagascar species of this genus have not yet been described.
Class Periporatae IVERSENet TROELSSMITH, 1950 Genus Buttinia BOLTENHAGEN, 1967 Buttinia andreevi BOLTENHAGEN, 1967 (Plate XI, 2, 3) Literature: "type S 231", JARDINI~and MAGLOIRE, 1965, p.208, pl.V, fig. 8. Buttinia andreevi BOLTENHAGEN, 1967, p.342, pl.lI, fig.5-7.
PLATE XI 1. The~pesiapopulnea COgREA,Recent. 2. Buttinia andreevi BOLTENHAGEN,Colombia, upper focus. 3. Buttiniaandreevi BOLTENHAGEN,Colombia, lower focus. Magnification × 1,000. 316
Rev. Palaeobotan.PalynoL, 6 (1968) 189-348
P L A T E XI
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
317
Description: Single grain, centro-symmetrical, isopolar, spherical. Apertures 20 or more, ectexinous and endexinous, rounded to angular, 7-10 # wide, 3-5/~ apart. Endexine 2 / , thick; columellae <-. I # long, < ½ # thick, only visible in well preserved grains; tectum reduced to rounded ridges, ½/~ thick, 1½-2 # wide, between the pores, psilate. Dimensions." 40-55/z. Variability: There is only slight variability in size and wall thickness. Comments: This species has already been described and figured without naming from the Senonian of western Africa by JARDIN~ and MAGLOIRE(1965) and was recently named by BOLTENHAGEN(1967). None of these authors has observed the presence of columellae and tectum, which in our opinion proves angiospermous affinities and permits the assignment to the class Periporatae. Distribution." Both in Nigeria and the Caribbean area restricted to the Proteacidites dehaani Zone. In Senegal and Gabon also restricted to the Senonian. Not recorded from Borneo. Taxonomic affinities: Unknown. Genus Echiperiporites VAN DER HAMMENet WYMSTRA,1964
Echiperiporites estelae nov. sp. (Plate X, I; holotype) Derivatio nominis: Named in honour of Mrs. Estela Bradley de Giacomo in recognition of her contribution to Venezuelan palynology. Holotype: Slide TC-162, surface sample MQ-1189, northwestern Borneo. Description: Single grain, centro-symmetrical, isopolar, spherical; periporate, pores 20-24, ectexinous and endexinous, slightly annulate, annuli 1½-2 # wide; pores 4-6 # wide, 10-12/~ apart. Endexine 1 ~ thick; columellae ~z ½/~ thick, ~ 1 /~ long; tectum smooth, -:< 1/~ thick, thickened at roots of spines; spines 6-9 # long, 2-4/~ thick at base, conical, blunt, 6-10/~ apart. Dimensions." 55-87/~, excluding spines. Variability: The species as defined here shows considerable variation in size, coarseness of wall structure and spines, density of spines and in number of pores. Distribution: The oldest occurrences are known from the Caribbean area where the species starts in the middle of the Eocene (Verrucatosporites usmensis Zone). In Nigeria the species is very rare and known virtually only from the Magnastriatites howardi Zone upwards. In Borneo it is occurring regularly in the Echitricolporites spinosus and Crassoretitriletes vanraadshooveni Zones and is probably absent in earlier periods. Taxonomic affinities: Due to the rather large variability of this species it is difficult to indicate the taxonomic affinity with certainty. The majority of the 318
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specimens agree well with pollen of Thespesia populnea (Malvaceae, Plate XI, 1), but larger grains could be more related to Hibiscus tiliaceus (Malvaceae). Ipomoea pollen grains have generally more pores and are more densely spinose, but otherwise belong to this group of species. Class Fenestratae IVERSEN et TROELS SMITH, 1950 Genus Fenestrites (VAN DER HAMMEN, 1956b)
Lectogenotype: Fenestrites spinosus VAN DER HAMMEN, 1956b. Remarks: Since Van der Hammen has invalidly indicated a recent pollen grain as type specimen, his genus is hereby legalized by selecting as lectogenotype the fossil species as described below. Fenestrites spinosus ex VAN DER HAMMEN, 1956b (Plate XII, 1) Literature: Fenestrites spinosus VAN DER HAMMEN, 1956b, p.97, pl.12, fig.38. Description: Single grain, radially symmetrical, isopolar, spherical; outline In polar view almost hexangular. Colpi and pori indistinct, probably tricolporate. Exine differentiated into a pattern of intectate lacunae (fenestrae), 8-11 /~ wide and tectate-columellate cristae. Columellae 1½ # long, ½/z thick; cristae 1-1½ # wide, 1/t high, bearing single rows of spines, 2 # long, 1 # wide at base. Dimensions: 30-38 # (including cristae, excluding spines). Variability: In size and coarseness of ornamentation. Sometimes undulating cristae have been observed. Distribution: Restricted to the middle and upper part of the Echitricolporites spinosus Zone. More frequently observed in the Caribbean area than elsewhere. Taxonomic affinities: This species is typical for the liguliflorae pollen type of the Asteraceae (Compositae), which is produced by a large number of genera. Of the many species which produce this pollen type, the following only will be mentioned as coming close to the fossil grains: Elephantopus angustifolia, Rolandia fruticosa (Plate XII, 3), Vernonia canescens, Vernonia remotiflora (Plate XII, 2). Class Tricolpatae IVERSEN et TROELS SMITH, 1950 Genus Striatricolpites (VAN DER HAMMEN, 1956b) ex GONZALEZ, 1967
Striatricolpites catatumbus GONZALEZ, 1967 (Plate XII, 4) Rev. Palaeobotan.Palynol., 6 0968) 189-348
319
Literature: Striatricolpites catatumbus GONZALEZ, 1967, p.30, pl. VIII, fig.7. Description: Single grain, radially symmetrical, isopolar, prolate; outline
in polar view trilobate to spherical. Tricolpate, colpi ectexinous, long, intruding with straight simple borders and pointed ends. Pores absent or indistinct. Endexine 1 # thick, columellae simple, ½ # long and ½/~ thick, slightly longer on poles, linearly arranged underneath striae of tectum; tectum striate; striae 1 # thick, 1-1½/~ wide, 1 # apart, subparallel or slightly anastomosing; between striae tectum very thin, sometimes finely perforate. Dimensions: 33-50/~. Variability: Some variability exists in size and in coarseness of wall structure and presence or absence of indistinct pores. The specimens described here agree in all respects with Gonzalez' type material. Tricolpate striate types described by MULLER (1968) from the uppermost Cretaceous of Borneo are considered to be specifically distinct. Distribution: Both in the Caribbean area and in Nigeria occurring from the base of the Retibrevitricolpites triangulatus Zone upwards. In Borneo the lower limit is not exactly known, but a related species occurs already in the Paleocene. Taxonomic affinities: Closest resemblance is with pollen of the genus Crudia (Fabaceae, Plate XII, 5, 6), but Anthonotha and Isoberlinia (Fabaceae) have similar pollen. Macrolobium bifilium (Fabaceae) has a much coarser striate pattern but is otherwise similar. It is not yet possible to be more precise about the affinities of this rather variable pollen species. Genus Perfotricolpites GONZALEZ, 1967 Perfotricolpites digitatus GONZALEZ, 1967
(Plate XII, 10) Literature: Perfotricopites digitatus GONZALEZ, 1967, p.34, pl.VI, fig. 1. Description: Single grain, radially symmetrical, isopolar, prolate. Tricolpate:
PLATE XII Fenestrites spinosus VAN DER HAMMEN,Venezuela. Vernonia remotiflora L. C. RICHARD,Recent. Rolandia fruticosa (LINNAEUS)KUNTZE,Recent. Striatricolpites catatumbus GONZALEZ,Colombia. Crudia amazonica SPRUCE, upper focus, Recent. Crudia amazonica SPRUCE, lower focus, Recent. Foveotricolpites perforatus VAN DERHAMMENet GARCIA,Venezuela, upper focus. Foveotricolpites perforatus VANDERHAMMENet GARCIA,Venezuela, lower focus. Foveotricolpites perforatus VANDERHAMMENet GARCIA,Venezuela. 10. Perfotricolpites digitatus GONZALEZ,Venezuela. 1. 2. 3. 4. 5. 6. 7. 8. 9.
Magnification × 1,000. 320
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
PLATE
XII
r
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~ Rev. Palaeobotan. Palynol., 6 (1968) 189-348
l
O 321
colpi ectexinous, long, strongly intruding, with straight borders and pointed ends. Pores very indistinct, if present endexinous. Endexine ½ /~ thick; columellae digitate, 2-2½/~ long, 1 p thick at base, ½ I~ thick at top of branches; tectum thin, finely reticulate-perforate, lumina ~ ½ ~ in width. Dimensions: 46-70 #. Variability: Occasionally in Venezuela pericolpate specimens are found, which because of the very typical wall structure should be included in the species. Whether some specimens observed in Nigeria with large round endexinous pores should be included is more doubtful. Distribution: Both in the Caribbean area and Nigeria occurring for the first time approximately at the base of the Verrucatosporites usmensis Zone, but, while continuously present in the former area up to Recent, in Nigeria disappearing from the record in the upper part of the Magnastriatites howardi Zone. In Borneo present at least from the base of the Echitricolporites spinosus Zone upwards. Taxonomic affinities: The pollen grains of Merremia glabra (Plate XIII, 2) and M. umbellata (Convolvulaceae) are rather similar. Identification of the fossil dispersed pollen with Merremia appears fairly reliable. Branched columellae are also found in Scaevola (Goodeniaceae, Plate XIII, 1) the pollen of which differs in the presence of costate endexinous pores and much thicker wall on poles. Valerianella stenocarpa (Valerianaceae) has also slightly similar pollen. Genus Foveotricolpites VAN DER HAMMEN et QARCIA, 1966 Foveotricolpites perforatus VAN DER HAMMEN et GARCIA, 1966 (Plate XII, 7, 8, 9) Literature: Foveotricolpites perforatus VAN DER HAMMEN et GARCIA, 1966, p.l12, fig.18. Description: Single grain, radially symmetrical, isopolar, subprolate. Tricolpate, colpi ectexinous, medium long, with straight borders and pointed ends. Endexine < 1 # thick; columellae ½-1 # thick and long, tightly packed in an irregular pattern; tectum 1 # thick, foveolate; lumina rounded oval, 1-2/~ wide, coarser, up to 3# wide on poles, approx. 3/~ apart.
PLATE XIII 1. Scaevola plumieri VAI4L,Recent. 2. Merremia glabra HALUER(ill.), Recent. 3. Stephanoeolpites eostatus VAN DER HAMMEN, Venezuela. 4. Tabernaemontana attenuata URBAN,upper focus, Recent. 5. Tabernaemontana attenuata URBAN,lower focus, Recent. 6. Gemmastephanocolpites gemmatus VAN DER HAMMENet GARCIA,polar view, Venezuela. 7. Gemmastephanocolpites gemmatus VAN DER HAMMENet GARCIA,equatorial view, Venezuela. Magnification × 1,000. 322
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
.........
x
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Dimensions: 44--64/z. Variability: A well characterized species with some variability in size and coarseness of wall structure. Distribution: Restricted to the Foveotricolpites perforatus Zone of the Caribbean area. Taxonomic affinities: Unknown.
Class Stephanocolpatae IVERSENet TROELS SMITH, 1950 Genus Stephanocolpites (VAN DER HAMMEN, 1954) ex R. POTONII~, 1960
Stephanocolpites costatus VAN DER HAMMEN, 1954 (Plate XIII, 3)
Literature: Stephanocolpites costatus VAN DER HAMMEN, 1954, p.92, pl.7, fig.9.
Remarks: The original short diagnosis is here enlarged. The identity of the specimens described by us has been confrmed by Van der Hammen. Description: Single grain, radially symmetrical, isopolar, spherical; outline in polar view circular. Apertures 5-6; ectexinous, 10-12 # long colpi and one fused circular endexinous aperture which is distinctly costate. Endexine < ½ p thick, columella < ½ # long, < ½/~ thick; tectate-foveolate, tectum < ½/t thick, lumina oval to circular up to 1 # in diameter, coarser on poles, muri rounded, 1-1½/~ wide. Dimensions: 35-45 #. Variability: Only slightly variable in size and sculpture and distinctness of colpi. Distribution: Restricted to the lower part of the Proxapertites operculatus Zone in the Caribbean area (top in Ctenolophonidites lisamae Zone). Taxonomic affinities: Unknown. A similar aperture combination has, however, been found in Tabernaemontana attenuata (Apocynaceae, Plate XIII, 4, 5), the wall structure of which is much finer reticulate, while the equatorial endexinous aperture is much wider and less costate. Genus Gemmastephanocolpites VAN DER HAMMENet GARCIA, 1966
Gemmastephanocolpites gemmatus VAN DER HAMMENet GARCIA, 1966 (Plate XIII, 6, 7) Literature: Gemmastephanocolpites gemmatus VAN DER HAMMENet GARCIA, 1966, p.110, fig.12. 324
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
Description: Single grain, radially symmetrical, isopolar, spherical; outline in polar view circular. Apertures 5-6; ectexinous, 10-12 /t long colpi and one fused circular endexinous aperture which is distinctly costate. Endexine < 1 /~ thick, columellae < 1 /~ long, ½/~ thick; tectum smooth, covered with verrucae or gemmae 1-2/~ in diameter, 1 /~ thick, generally situated on top of columellae, but rather irregularly distributed. Dimensions: 33-42 #. Variability: In size and coarseness of sculpture. Distribution: Restricted to the Ctenolophonidites lisamae and the Foveotricolpites perforatus Zones in the Caribbean area. Taxonomic affinities: No comparable Recent plant species is known, but the distinct resemblance with Stephanocolpites costatus and its occurrence at a stratigraphically higher level suggest a phylogenetic relationship between the two. Genus Retistephanocolpites LEIDELMEYER,1966
Retistephanocolpites williamsi nov. sp. (Plate XIV, 1, 2; holotype) Derivatio nominis: Named in honour of Mr. R. W. Williams in recognition of his contribution to Nigerian palynology. Holotype: Slide TC-163, well Ubulu-1, 3000 ft., Nigeria. Description: Single grain, radially symmetrical, isopolar, oblate. 6-7 colpate, colpi ectexinous, 14 # long. Wall 221--4/z thick; endexine 1-2½/z thick, columellae 1 # long and thick, irregularly arranged and forming a spongy structure; tectum < 1 /z thick, reticulate-foveolate; lumina oval to circular 1-2 # in diameter, muri 1 # wide. Dimensions: 4 1 4 7 #. Variability: There exists considerable variation in the coarseness of the sculpture and some in the thickness of the endexine. D&tribution: Absent in the Caribbean area, in Nigeria occurring from the base of the Proxapertites operculatus Zone upwards to the middle of the Verrucatosporites usmens& Zone. In Borneo known from the Neogene, base not exactly known. Taxonomic affinities: The combination of 5-6 short apertures, spongy columellate structure and reticulate-foveolate tectum is so far only known from Ctenolophon parvifolius (Ctenolophonaceae, Plate XIV, 3, 4) which differs only in the 2-3/z wide muri. Identification with this Indo-Malesian species appears highly probable. Genus Cteno/ophonidites VAN HOEKEN-KLINKENBERG,1966
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
325
Ctenolophonidites costatus (VAN HOEKEN-KLINKENBERG, 1964) ex VAN HOEKENKLINKENBERG, 1966 (Plate XIV, 5, 6) Literature: KUYL et al. (1955, p.2, fig.10, 12, 13). Stephanocolpites costatus VAN HOEKEN-KLINKENBERG, 1964, p.221, pl.4, fig.10. Ctenolophonidites costatus VAN HOEKEN-KLINKENBERG, 1966, p.42. Description: Single grain, radially symmetrical, isopolar, spherical-oblate; 6-colpate; colpi ectexinous, 24 # long, slightly costate equatorially. Ectexine locally thickened into a pattern of radial costae, meeting near the poles and forming ring-like ridges, occasionally with extra ridges inside these rings; ridges 1½-2 # high, 5 p wide. Columellae and tectum not differentiated, wall psilate, 3-4½ p thick at equator and apparently densely and finely perforated in all directions, creating a spongy effect which diffuses the light considerably. Dimensions: 37-50 #. Variability: In size and coarseness of wall structure. Distribution: Only known from Nigeria where the species already occurs in the Proteacidites dehaani Zone, is temporarily absent in the higher part of the Proxapertites operculatus Zone, to be present again from the base of the Monoporites annulatus Zone up to Recent. Taxonomic affinities: Agrees in all essential details with the pollen of Ctenolophon engleri (Ctenolophonaceae, Plate XV, 1,2) except its smaller size. This pollen type is not known from any other plant as yet (cf. also SAAD,1962). Ctenolophonidites lisamae (VAN DER HAMMEN et GARCIA, 1966) nov. comb. (Plate XIV, 7, 8) Literature: Scabrastephanocolpites lisamae VAN DER HAMMEN et GARCIA, 1966, p.ll0, fig.14.
PLATE XIV 1. Retistephanocolpites williamsi nov. sp., Nigeria, holotype, upper focus. 2. Retistephanocolpites williamsi nov. sp., Nigeria, holotype, lower focus. 3. Ctenolophon parvifolius OLIVER,upper focus, Recent. 4. Ctenolophon parvifolius OUVER,lower focus, Recent. 5. Ctenolophonidites costatus VAN HOEKEN-KLINKENBER~,Nigeria, upper focus. 6. Ctenolophonidites costatus VAN HOEKEN-KUNKENaERG,Nigeria, lower focus. 7. Ctenolophonidites lisamae VAN DER HAMMENet GARC~A,Venezuela, polar view. 8. Ctenolophonidites lisamae VAN DER HAMMENet GARCIA,Venezuela, equatorial view. Magnification × 1,000.
326
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
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Description: Single grain, radially symmetrical, isopolar, spherical-suboblate; outline in polar view stellate-circular. 5-colpate, colpi 14 .u long, ectexinous, slightly costate equatorially. Ectexine locally thickened into a pattern of radial costae, joining in pairs around the terminations of the colpi, not touching near poles; ridges 12~--2bt high, 2-3 ,u wide. Columellae and tectum not differentiated; wall finely scabrate, 3-4½ # thick at equator, apparently densely perforated in all directions, creating a spongy effect which diffuses the light considerably. Dimensions: 17-31 #. Variability: Some variability is present in the way in which the ridges unite with each other. Comments: In view of the close relationship which exists between this species and Ctenolophonidites costatus, we have transferred it to the latter genus. The identity of our specimens has been confirmed by Van der Hammen. Distribution: Virtually restricted to the Ctenolophonidites lisamae and Foveotricolpites perforatus Zones in the Caribbean area. Taxonomic affinities: Has in all probability been derived from an extinct species of Ctenolophon (Ctenolophonaceae).
Class Tricolporatae |VERSEN et TROELS SMITH, 1950 Genus Psilatricolporites (VAN DER HAMMEN, 1956) ex VAN DER HAMMENet WYMSTRA, 1964
Psilatrieolporites operculatus VAN DER HAMMENet WYMSTRA, 1964 (Plate XV, 3)
Literature: Psilatricolporites operculatus VAN DER HAMMEN et WYMSTRA, 1964, p.236, pl.1, fig. 13. Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view circular to slightly semi-angular. Tricolporate; colpi long, ectexinous,
PLATE XV 1. 2. 3. 4. 5. 6. 7. 8. 9.
Ctenolophon engleri MILDBREAD, upper focus, Recent. Ctenolophon engleri MILDBREAD, lower focus, Recent. Psilatricolporites operculatus VAN DER HAMMENet WYMSTRA, Surinam. Alchornea cordifolia MUELLER-ARG., Recent. Alckornea obovata PAX et HOFFMANN, Recent. Zonocostites ramonae nov. gen., nov. sp., Borneo, holotype. Zonocostites ramonae nov. gen., nov. sp,, Borneo, holotype. Rhizopkora rnucronata LAMARCK,upper focus, Recent. Rhizophora mucronata LAMARCK,lower focus, Recent.
Magnification × 1,000. 328
Rev. Palaeobotan.Palynol., 6 0968) 189-348
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marginate and provided with distinct opercula of identical structure as found in margins; opercula 1½ # wide at equator; pores distinct only in equatorial view, endexinous, equatorially elongated with indistinct borders. Endexine ~ ½/~ thick; columellae < ½ # thick and long, slightly larger at margins of colpi; tectum ~( ½ # thick, finely perforate, but ~ ½/~ thick and less finely perforate at margins of colpi. Dimensions: 17-28 #. Variability: Margins of colpi vary in extent and thickness. Distribution: In the Caribbean area present from the base of the Psilatricolporites operculatus Zone upwards. In Nigeria the first occurrence is slightly higher, at the base of the Verrucatosporites usmensis Zone. In Borneo this species is regularly present in the Neogene, but its base has not yet been defined. Taxonomic affinities: This species shows a striking resemblance to the pollen of the genus Alchornea (Euphorbiaceae). The pollen of Alchornea cordifolia (Plate XV, 4) is very similar, that ofA. obovata (Plate XV, 5) and A.javanensis has smaller colpi and opercula, but larger margins. Psilatricolporites crassus VAN DER HAMMEN et (Plate XVI, 1, 2)
WYMSTRA,
1964
Literature: Psilatricolporites crassus VAN DER HAMMEN et WYMSTRA, 1964, p.237, pl.1, fig. 1-4. Description: Single grain, radially symmetrical, isopolar, spherical to subprolate; outline in polar view circular. Tricolporate; colpi medium long, ectexinous, straight with pointed ends; pores endexinous, equatorially elongated, oval or slitshaped, 15-19 # long, distinctly costate, costae 5 # wide and up to 4½ # thick, parallel to the pores. Endexine 1½/z thick, columellae ½ # thick and 1 /z long, tectum psilate to finely perforate-foveolate, 1-1½/z thick.
PLATE XVI 1. Psilatricolporites crassus VAN DER HAMMENet WYMSTRA,Nigeria. 2. Psilatricolporites crassus VAN DER HAMMENet WYMSTRA,Venezuela. 3. Hura crepitans LINNAEUS, upper focus, Recent. 4. Hura crepitans LINNAEUS, lower focus, Recent. 5. Verrutricolporites rotundiporis VAN DER HAMMENet WYMSTRA, Trinidad. 6. Verrutricolporites rotundiporis VAN DER HAMMENet WYMSTRA,Surinam. 7. Verrutricolporites rotundiporis VAN D~R HAMMENet WYMSTRA, Nigeria. 8. Crenea maritima AUBLET, Recent. 9. Crenea maritima AUBLET, upper focus, Recent. 10. Crenea maritima AUaLE'r, lower focus, Recent. 11. Echitricolporites spinosus VAN DER HAMMEN, upper focus, Venezuela. 12. Echitricolporites spinosus VAN DER HAMMEN, lower focus, Venezuela. 13. Riencourtia glomerata CASS, upper focus, Recent. 14. Riencourtia glomerata CASS, lower focus, Recent. Magnification × 1,000.
330
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
PLATE XVI
Dimensions: 41-70 ,u. Variability: This species is very variable in size, thickness of wall, especially the endexine, dimensions of columellae and width of the perforations. It is, moreover, susceptible to corrosion of the tectum, which may lead to pseudo-ornamentations such as areolate sculpture with widely spaced irregular grooves, geminate sculpture with deep grooves, verrucate sculpture, densely intersected by grooves or scabrate sculpture with the columellae protruding through membrane-thin remnants of the tectum. Distribution: In the Caribbean area and in Nigeria occurring from the base of the Retibrevitricolporites triangulatus Zone upwards, in the Caribbean area up to the Recent, but in Nigeria not known at present (except introduced). Absent from Borneo. Taxonomic affinities: Closest resemblance is with pollen of the tropical American genus Hura (Euphorbiaceae) in which the tectum is not perforatefoveolate as in the fossil species, but psilate. Hura polyandra is very similar in its apertures, but in the pollen of Hura crepitans (Plate XVi, 3, 4) the ectexinous colpi are much longer than is found in Psilatricolporites crassus. The pollen types found in Sapium (Euphorbiaceae) are more different. It is possible that the fossil species may represent an extinct species of Hura or that the pollen type of this genus may have changed its appearance slightly. The dominance of Hura crepitans at present in the Caribbean coastal environment forms a strong additional argument for assigning the fossil species to Hura. However, the absence of Hura in the present day natural vegetation of Nigeria (Hura senegalensis is, according to HUTCHINSON and DALZIEL (1954) probably imported) casts doubt on the affinities of the Nigerian grains assigned to the species. Recently LANGENHEIMet al. (1967) have described a fossil pollen closely resembling that of Pelliciera rhizophorae (Theaceae) from the Oligo-Miocene of Chiapas (Mexico). The resemblance to some variations of PsilatricoIporites crassus is striking indeed and the possibility that this monotypic mangrove genus had formerly a much wider range is worth further investigation. Genus Zonocostites nov. gen.
Derivatio nominis: Name derived from the costate endexinous apertures. Diagnosis: Spherical to subprolate, tricolporate; colpi relatively short, endexinous apertures equatorially elongated or almost fused, distinctly costate; wall tectate, finely perforate, thin, often almost psilate on equator, or thicker at poles, due to longer columellae. Type species: Zonocostites ramonae nov. sp. Remarks: This genus is intended to accommodate fossil dispersed pollen of the Rhizophora-Bruguiera type.
332
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
Zonocostites ramonae nov. sp. (Plate XV, 6; holotype; Plate XV, 7) Literature: Rhizophora-type MULLER 1964, p.37, pl.I, fig.3. Derivatio nominis: Named in honour of Miss Ramona Henriquez in recognition of her contribution to Venezuelan palynology. Holotype: Slide TC-164, well CO-77, 3600 ft., Trinidad. Description: Single grain, radially symmetrical, isopolar, spherical. Tricolporate, colpi ectexinous, medium long, straight with pointed ends, slightly costate, endexinous apertures equatorially elongated to almost fused, distinctly costate, in polar view slightly vestibulate. Endexine ~ ½/z thick; columellae < ½ # thick and high; tectum < ½ # thick, densely perforate, coarser on poles and finer to almost psilate on equatorial belt, perforations < ½/~ wide. Dimensions: 16-19 bt. Variability: This is a very variable species, especially in size and coarseness of structure and perforations on the poles. Attempts to separate subtypes corresponding to Recent species of Rhizophoraceae have been unsuccessful. Distribution: The earliest positive occurrences of Zonocostites ramonae are known from the Verrucatosporites usmensis Zone in the Caribbean area, with doubtful ones from the Monoporites annulatus Zone. In Nigeria the first appearances are later and occur around the base of the MagnastriatiteshowardiZone. In Borneo Eocene sediments unfortunately do not carry well enough preserved microfloras to permit positive identification, but in the Verrucatosporites usmensis Zone the species does occur. These pre-Miocene occurrences are all in low frequencies. Approximately at the Oligo-Miocene transition (lower part of the Magnastriatites howardi Zone) in all three areas a distinct quantitative increase can be observed and the species remains dominant in the coastal and marine sediments of the whole tropics up to Recent. Taxonomic affinities: The rather wide limits adopted for this species include the pollen types produced by the various species of the genera Rhizophora (Plate XV, 8, 9), Bruguiera, Ceriops, and Carallia (Rhizophoraceae). Specific differences exist, but in general the preservation of the fossil grains does not allow their recognition. Confusion with pollen of other taxa appears unlikely, however. Genus Verrutricolporites VAN DER HAMMENet WYMSTRA,1964
Verrutricolporites rotundiporis VAN DER HAMMENet WYMSTRA,1964 (Plate XVI, 5, 6, 7) Literature: Verrutricolporites rotundiporis VAN DER HAMMEN et WYMSTRA, 1964, p.237, pl.I, fig.14.
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
333
Description: Single grain, radially symmetrical, isopolar, spherical to subprolate; outline in polar view lobate. Tricolporate, apertures interlobate; colpi ectexinous, indistinct, medium long, intruding; pores endexinous, circular, 2-3/z in diameter, sharply outlined. Total wall thickness approx. 1 /~; endexine ~ ~/~ thick, columellae thin, but generally clearly visible, straight, ½ /z long; tectum ½ # thick, psilate or covered by low, irregularly shaped verrucae, 1-2 # in diameter and up to ½/~ high. Dimensions: 15-24 ~u. Variability: Mainly in the development of the verrucate sculpture. All transitions between almost psilate and strongly verrucate grains can be observed and it has proved impossible to arrive at a separation between a psilate and a verrucate type, in conformity with Van der Hammen and Wymstra's experience. The ectexinous furrows are only rarely clearly outlined and, when the grains are folded together, mostly hidden between the lobes. Comments: Our description agrees well with the one given by VAN OER HA~aMEN and WVMSa'RA (1964), but we would stress in addition the trilobate condition, which often causes the compressed grains to assume a characteristic folded appearance with the pores often half hidden by the folds. There is evidence for a gradual increase in degree of verrucation from older to younger strata, but the phenomenon is not clear enough to be used for stratigraphical interpretation without detailed statistical analysis. A comparable degree of variation may exist in the genus Crenea which has probably produced the fossil species. There exists some superficial similarity with FIorschuetzia trilobata, the points of difference being the smaller size, distinct columellae, tectate-verrucate sculpture with equal wall thickness over the entire grain in Verrutricolporites rotundiporis. Distribution: In the Caribbean area the first occurrences are around the base of the Magnastriatites howardi Zone; it is very abundant in the coastal and marine sediments of the Verrutricolporites rotundiporis Zone and afterwards decreases in numbers. In Nigeria the first occurrence is at the base of the Verrutricolporites rotundiporis Zone. In the Caribbean area present up to the present day, in Nigeria scattered rare occurrences from the base Echitricolporites spinosus Zone. Absent from Borneo. Taxonomic affinities: The pollen of Crenea maritima (Plate XVI, 8, 9, 10) agrees in all essential details with Verrutricolporites rotundiporis, but is more variable. Investigation of Crenea pollen from various localities revealed a variability in degree of verrucation which is paralleled in the fossil material. However, in view of the stratigraphical trend towards increased verrucation, one might expect the recent relatives to show the highest degree of verrucation and this is definitely not the case. It may be mentioned here that, according to information kindly supplied by Prof. F. P. Jonker, Utrecht, several species of Crenea described from the tropical South American coastline are considered by him to be synonyms of Crenea maritima, with the possible exception of Crenea patentinervis STANDLEV, 334
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
1947, of which unfortunately no material was available for comparison. The dominance of Verrutricolporites rotundiporis in coastal and marine sediments is in agreement with the present day habitat of Crenea, growing in swampy places along river courses and in the mangrove vegetation. Some superficial resemblance exists with the pollen of Sonneratia apetala, but this is considerably larger, has no ectexinous colpate apertures and shows a graded development in the verrucate sculpture which is coarser on poles. Genus Echitricolporites VAN DER HAMMEN, 1956b. Lectogenotype: Echitricolporites spinosus VAN DER HAMMEN, 1956b
Remarks: The genus is here validated by selecting a lectogenotype, since Van der Hammen has invalidly indicated the pollen of a Recent species as genotype.
Echitricolporites spinosus VAN DER HAMMEN, 1956b (Plate XVI, 11, 12)
Literature: Echitricolporites spinosus VAN DER HAMMEN, 1956b, p.92, pl.10, fig.30.
Remarks: Van der Hammen's name is here validated by selecting a fossil grain as type.
Description: Single grain, radially symmetrical, isopolar, spherical. Tricolporate; colpi ectexinous, straight with pointed ends, fairly long; pores indistinct. Endexine < ½ # thick; columellae ½ # long (½-1/z long underneath spines), < ½-# thick; tectate-echinate, tectum < ½ # thick, spines 3-6 # long, 2-4 /z thick at base, sharply pointed, rather densely spaced. Dimensions: 23 # (excl. spines). Variability: A rather large amount of variability is found in size and in degree of spinosity. However, the spines are always separated and not connected by a reticulate pattern of muri. Distribution: In all three areas investigated virtually restricted to the Echitricolporites spinosus Zone. In the Caribbean area scarce occurrences are known, however, from the Crassoretitriletes vanraadshooveni and upper part of the Magnastriatites howardi Zones. Most numerous in the Caribbean Mio-Pliocene sediments, rare in Nigeria, fairly common in Borneo. Taxonomic affinities: This is the tubuliflorae type of the Asteraceae (Compositae). Very similar pollen types are found among the genera Espeletia, Mikania, Pectis, Riencourtia (Plate XVI, 13, 14), Wedelia, and Wulffia and closer identification will prove to be very difficult. Also many extratropical genera of Asteraceae show this pollen type. For a further discussion of its possible origin see the section on "Botanical results". Rev. Palaeobotan.Palynol., 6 (1968) 189-348
335
Echitricolporites meneillyi nov. sp. (Plate XVII, 1; holotype) Derivatio nominis: Named in honour of Mr. D. G. R. Mcneill in recognition of his contribution to Trinidadian palynology. Holotype: Slide TC-165, well CO-73, 333 ft., Trinidad. Description: Single grain, radially symmetrical, isopolar, spherical; outline in polar view trilobate. Tricolporate; colpi ectexinous, fairly long, straight with pointed ends; pores indistinct. Endexine * ½/2 thick; columellae ~--1 /2 high, ¢/2 long (slightly longer underneath spines), . ½ /2 thick; tectate echinate, tectum ½ # thick, spines < 1 /2 long, < ½/2 thick at base, 2-3/2 apart. Dimensions: 23/2. Variability: Slight variability in size and coarseness of sculpture. Comments: The species differs from Echitricolporites eehinatus in its much smaller and more widely spaced spines. Distribution: Only found in the Caribbean area, where it occurs from the base of the Echitricolporites mcneillyi Zone upwards. Taxonomic affinities: This is a small-spined subtype of the tubuliflorae pollen type of the Asteraceae. It is found in the genera Ambrosia (Plate XV[I, 2, 3), Crassocephalum, Ira, and Xanthium. Of these Xanthium forms, with its coarser sculpture, a transition to the larger spirted tubuliflorae type. Ambrosia and lva come very close to the fossil grains. Genus Retitricolporites (VAN DER HAMMEN, 1956) ex VAN DER HAMMEN et WYMSTRA, 1964
Retitricolporites guianensis VAN DER HAMMEN et WYMSTRA, 1964 (Plate XVII, 8, 9)
P L A T E XVII 1. Echitricotporites mcneillyi nov. sp., Trinidad, holotype. 2. Ambrosia cumanensis KUNTH, upper focus, Recent. 3. Ambrosia eumanensis KUNTH, lower focus, Recent.
4. Retitricolporites irregularis VAN DER HAMMENet WVMSTRA,Venezuela, upper focus. 5. Retitricolporites irregularis VAN DER HAMMENet WYMSTRA,Venezuela, lower focus. 6. Amanoa oblongifolia MUELLER-ARG.,upper focus, Recent. 7. Amanoa oblongifolia MUELLER-ARG.,lower focus, Recent. 8. Retitrieolporites guianensis VAN DEn 1-1AMMENet WVMSTRA,Surinam. 9. Retitricolporites guianensis VAN DER HAMMENet WYMSTRA,Surinam. 10. Bombaeaeidites annae (VANDER HAM~E~),Venezuela. 11. Bombax eeiba LINNAEUS,upper focus, Recent. 12. Bombax eeiba LINNAEUS,lower focus, Recent. Magnification × 1,000. 336
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
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Literature: Retitricolporites guianensis VAN DER HAMMENet WYMSTRA,1964, p.235, pl.IH, fig.l-2. Description: Single grain, radially symmetrical, isopolar, prolate. Tricolporate; colpi ectexinous, long and intruding with straight, marginate borders and pointed ends; pores endexinous, circular, 1½-2 # wide, rather indistinct. Endexine ½/z thick; columellae ½/z thick and long, regularly distributed and rather closely spaced; tectum ½ # thick, reticulate; muri ½/~ thick and high, multicolumellhte, but not always distinctly visible, lumina of angular shape, slightly elongated, 3-4/z wide, diminishing in size towards colpi. Dimensions: 28-47/z. Variability: Size and shape of this species are rather variable, the smaller specimens showing a finer ornamentation. The species can, however, be easily recognized by its loose-meshed reticulate sculpture with angular shape of the lumina and thin, low muri. In well preserved specimens the regularly distributed columellae are characteristic. Comments: Inspection of type material has shown the identity of the specimens described here with Retitricolporites guianensis. Our description, however, differs slightly from the one given by VAN DER HAMMEN and WYMSTRA(1964). Distribution: Only known from the Caribbean area where it occurs from the base of the Retitricolporites guianensis Zone upwards. Taxonomic affinities: A certain resemblance exists with pollen of Firrniania colorata and Hildegardia barteri (Sterculiaceae), but a striking difference is the finely reticulate appearance of the fairly broad muff in these types. To a lesser degree this is the difference also with pollen of Glossosternon bruguieri (Sterculiaceae). The pollen of Pterocyrnbiurn beccarii has finely reticulate muri and in addition a thicker wall. Pollen of Sterculia rnexicana has a thicker wall and is finer reticulate on the poles. Trichospermurn pollen (Tiliaceae) has distinctly equatorially elongated pores, although the wall structure is strikingly similar. In view of this situation it is not yet possible to come to a firm decision which taxon has produced Retitricolporites guianensis pollen. However, Sterculiaceae and Tiliaceae are the only families in which this pollen type has been found so far. Retitricolporites irregularis VAN DER HAMMENet WYMSTRA,1964 (Plate XVII, 4, 5) Literature: Retitricolporites irregularis VAN DER HAMMENet WYMSTRA,1964, p.235, pl.III, fig. 9, 10. Description: Single grain, radially symmetrical, isopolar, spherical; outline in polar view circular. Tricolporate; colpi ectexinous, long, strongly intruding with straight costate borders and pointed ends; costae 2/z thick and wide; pores endexinous, oval, 2-3 # wide, equatorially elongated, slightly costate. Endexine 338
Rev. Palaeobotan.Palynol., 6 (1968) 189--348
< 1 # thick, columellae <~ ½/~ thick and long, arranged in a reticulate pattern and supporting in single rows a curvimurate reticulum; lumina of irregular shape, up to 5 / , wide, finer along colpi. Dimensions: 29-50 #. Variability: There is considerable variation in the coarseness of the ornamentation. Occasionally four colpi are present. Distribution: In the Caribbean area present from the base of the Retibrevitricolporites triangulatus Zone upwards. In Nigeria the first scattered occurrences are in the middle part of this zone. Taxonomic affinities: The closest resemblance is with Amanoa oblongifolia (Euphorbiaceae, Plate XVII, 6, 7), less so with Pseudolachnostylis glauca (Euphorbiaceae) which has non-costate apertures and a finer reticulation. Since the former species is, according to LINDEMAN(1953), abundant in scrub wood along creeks on peaty mud in Surinam, it is a likely candidate for producing the fairly large amounts of Retitricolporites irregularis found throughout its range in the Caribbean area. Genus Retibrevitricolpites VAN HOEKEN-KLINKENBERG,1966
Retibrevitricolpites triangulatus VAN HOEKEN-KLINKENBERG,1966 (Plate XVIII, 1, 2)
Literature: Retibrevitricolpites triangulatus VAN HOEKEN-KLINKENBERG, 1966, p.40, pl.II, fig.2. Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view subtriangular. Tricolporate; colpi 4 /* long, ectexinous, marginate, margins 1½ # wide, with thickened tectum; pores endexinous, equatorially elongated and vestibulate, 8/~ long; vestibulum 5 # wide, 1/~ high. Endexine { # thick; columellae 3 # thick and long, slightly longer around pores; tectum ½ # thick, near colpi 1-13 # thick, finely reticulate; lumina 13 # wide, rather angular in shape; perforate on poles; muri ½/~ thick and wide, on poles perforations 3 # wide and 3 # apart. Dimensions: 17-26/~. Variability: Rather pronounced variability in coarseness of sculpture, less so in size and thickness of wall. Comments: The description presented here differs from the original type description presented by the author, but agrees with GONZALEZ'description (1967). Inspection of type material has convinced us that our specimens can and should be incorporated in Brevitricolpites triangulatus VAN HOEKEN-KLINKENBERG.Since pores are present, this genus is here placed in the Class Tricolporatae. Distribution: Both in the Caribbean area and in Nigeria the first occurrence is at the base of the Retibrevitricolpites triangulatus Zone and disappearance at Rev. Palaeobotan. PalynoL, 6 (1968) 189-348
339
the top of the Verrucatosporites usmensis Zone. Absent from Borneo. Taxonomic affinities: Unknown, apparently extinct. Genus Bombacacidites COUPER, 1960 Bombacacidites annae (VAN DER HAMMEN, 1954)
(Plate XVII, 10) Literature: Tricolporites annae VAN DER HAMMEN, 1954, p.96, pl. 9. Retitricolporites (Bombacites) annae VAN DER HAMMEN et
GARCIA, 1966, p.112. Bombacacidites annae LEIDELMEYER, 1966, p.55. Description: Single grain, radially symmetrical, isopolar, oblate; in polar
view rounded-intersubangular. Tricolporate; colpi 14/~ long, ectexinous, slightly protruding, costate; costae 2 # wide; pores indistinct, endexinous, oval, equatorially elongated. Total wall thickness 1~-2/~; endexine ½ # thick; columellae present under muff of reticulum only, ½/z thick and long; tectum reduced to a reticulum; muri multicolumellate, z-17/z ~ 1 thick, ½-1 # high; lumina 1½#-2½/~ wide on poles and near colpi, much smaller on intercolpate areas, where the sculpture is almost perforate; transitions in sculptural distribution are gradual. Dimensions: 49-57 #. Variability: Size and coarseness of ornamentation are variable, but the multicolumellate structure underlying the muff is a fairly constant characteristic, although in badly preserved grains this may have been reduced to a finely granulate pattern. Comments: Our specimens agree with the type material, but in order to differentiate the species from other closely related bombacaceous grains, the recommendation is made to take the multicolumellate structure underlying the muri,
PLATE XVIII Retibrevitricolpites triangulat~s VAN HOEKEr~-KUNKENBERG,Venezuela, upper focus. Retibrevitricolpites triangulatus VAN HOEKEN-KuNKENBERG,Venezuela, lower focus. Margocolporites vanwijhei nov. sp., Venezuela, holotype. Caesalpinia coriaria WILDENOW,upper focus, Recent. Caesalpinia coriaria WILDENOW,lower focus, Recent. Jandufouria seamrogiformis nov. gen., nov. sp., Guyana, holotype. Catostemma altsonii SANDWITH,upper focus, Recent. Catostemma altsonii SANDW1TH,lower focus, Recent, Striasyncolpites zwaardi nov. gen, nov. sp., Trinidad, holotype. 10. Cuphea aequipetala CAVANILLIES,Recent. 11. Perisyncolporites pokornyi nov. gen., nov. sp., Venezuela, holotype. 12. Brachypteris ovata SMALL,Recent. 1. 2. 3. 4. 5. 6. 7. 8. 9.
Magnification x 1,000. 340
Rev. Palaeobotan. Palynol., 6 (1968) 189-348
0
m
.... V
¸
, ~
~ ~
~
i
~
~ili~i~ii~i ~
~ ~
~ ....
~
~
~,~,~
~i
which is not mentioned by VAN DER HAMMENand GARCIA(1966), as an additional typical feature. Distribution: In the Caribbean area restricted to the Ctenolophonidites lisamae and the Foveotricolpitesperforatus Zones. Absent from Borneo and Nigeria. Taxonomic affinities: Closest resemblance is with certain species of the genus Bombax (Bombacaceae). Especially close are Bombax ceiba (Plate XVII, II, 12), B. rhodognaphalon, and B. pubescens, which all show the multicolumellate structure in varying degrees. Bombax mexicana differs in the pronounced triangular shape. No other genus of Bombacaceae shows this pollen type and identification with a, possibly extinct species of Bombax appears well founded. Genus Margocolporites RAMANUJAM, 1966
Margocolporites vanwijhei nov. sp. (Plate XVIII, 3; holotype) Derivatio nominis: Named in honour of Mr. D. H. van Wijhe in recognition of his contribution to Nigerian palynology. Holotype: Slide TC-166, Venezuela. Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view circular. Tricolporate; colpi ectexinous, 10 # long, costate and surrounded by wide, finely baculate margins with straight edges and pointed ends which are or are not connected at the poles; costae 2 # wide; width of margins in equatorial plane 20/~; pores endexinous, round, 4-5 # in diameter, often slightly protruding. Endexine ½ # thick; columellae 1 # long, ½/~ thick; tectate-reticulate outside colpate margins, muri multicolumellate, 1 # thick and high; lumina 2-2½ # wide at equator, 1-11 # wide on poles. Colpate margins intectate, finely baculate because of densely spaced, evenly distributed columellae. Dimensions: 39-57/~. Variability: Size and coarseness of sculpture are rather variable, syncolporate and colporate grains are included, because in Recent relatives these variations occur within one and the same flower. Distribution: In the Caribbean area occurring approximately from the lower part of the Monoporites annulatus Zone upwards, in Nigeria restricted to the Verrucatosporites usmensis and Magnastriatites howardi Zones, and in Borneo occurring at least from the Magnastriatites howardi Zone upwards, base not yet determined, but absent from the Paleocene and Upper Cretaceous. Taxonomic affinities: Among the Fabaceae (Leguminosae)the following genera show strikingly similar pollen: Adipera, Brasilettia, Caesalpinia, Haematoxylon, Mezoneuron, and Poincianella. Without further detailed studies it is impossible to come to a closer identification of the fossil material. Especially similar, however, is the pollen of Caesalpinia bonduc and C. coriaria (Plate XVIII, 4, 5). 342
Rev. Palaeobotan.Palynol., 6 (1968) 189-348
Class Stephanocolporatae [VERSENet TROELSSMITH, 1950 Genus Jandufouria nov. gen.
Derivatio nominis: The genus has been named in honour of Prof. J. Dufour, who successfully stimulated the early palynological investigations in Venezuela. Diagnosis: Oblate, 4-6 colporate, colpi ectexinous, slightly costate, reaching approximately halfway the poles, endexinous pores indistinct, equatorially elongated, wall rather densely columellate, tectate-densely perforate, perforations evenly distributed, lumina < ½/~ in width. Type species: Jandufouria seamrogiformis nov. sp. Comments: This genus accommodates fossil pollen of the Catostemma type. It can be distinguished from Retistephanocolporites by its evenly and densely perforated tectum. Jandufouria seamrogiformis nov. sp. (Plate XVIII. 6; holotype) Derivatio nominis: Name derived from the resemblance in shape to the leaf of the Irish shamrock (Trifolium repens). Holotype: Slide TC-167, well Aurora-l, 651 ft., British Guyana. Description: Single grain, radially symmetrical, isopolar, oblate. 4-6 colporate; colpi ectexinous, 36/z long, reaching half-way the poles, slightly costate with straight borders and pointed ends, costae 1~-2 # wide; endexinous apertures equatorially elongated, faintly costate. Endexine 1 # thick; columellae -~-1 # long, ½ # thick; tectum ½-1 /~ thick, densely and evenly perforated. Dimensions: 40-57/~. Variability: There is some slight variability in size and in wall thickness, but as a rule the species is highly characteristic because of its shape. Distribution: Only known from the Caribbean area, where it occurs from the base of the Verrucatosporites usmensis Zone upwards. Taxonomic affinities: Close resemblance exists with the pollen of the genus Catostemma (Bombacaceae), especially with C. altsonii (Plate XVIII, 7, 8), C. sclerophyllum, and C. fragrans. C. commune has distinctly digitate columellae, a feature which has not been observed in the fossil material so far. The pollen of Aguiaria is similar, but tricolporate. The widespread occurrence of Catostemma in the rain-forests of tropical South America supports the identification.
Class Pericolporatae IVERSENet TROELSSMITH, 1950 Genus Perisyncolporites nov. gen.
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Derivatio nominis: Name derived from perisyncolporate apertures. Diagnosis: Spherical, often slightly angular grains. Ectexinous apertures syncolpate, arranged basically in a hexahedral pattern, with variations to higher orders (hepta- to dodecahedr,ql) or lower orders (penta- to tetrahedral) or any incomplete arrangement of the foregoing or absent. Endexinous apertures periporate, in syncolpate grains generally located eccentrically on colpi. Wall thick, tectate. Type species: Perisyncolporites pokornyi nov. sp. Comments: This genus is intended to include the very characteristic fossil malpighiaceous pollen grains listed below. Perisyneolporites pokornyi nov. sp. (Plate XVIII, 11 ; holotype) Derivatio nominis: Named in honour of Mr. G. Pokorny in recognition of his contribution to Colombian palynology. Holotype: Slide TC-168, well OG-1, 5828-5850 ft., Venezuela. Description: Single grain, radially symmetrical, often centro-symmetrical, isopolar, spherical; outline often angular in conformity with aperture pattern. Ectexinous apertures syncolpate, or nearly so, arranged in a complicated pattern, in general according to the ribs of a hexahedron, with variations to higher orders (heptadodecahedral patterns) or lower orders (penta- and tetrahedral patterns) or any incomplete arrangements of the foregoing, deviating in a zonate pattern or totally absent; colpi generally straight or rounded syncolpate, then often very wide and with relatively small intercolpate areas, sometimes very shallow, margins generally slightly costate, costae 1 gLthick, 3 p wide. Pores endexinous, generally circular to oval, 2½-4 t~ wide, if colpi present located eccentrically, frequently less pores than colpi. Endexine 2-3 p thick; columellae < 1 It long, < ½ F~ thick; tectum ½ p thick, slightly thickened along colpi, psilate. Dimensions: 25-47 #. Variability: As discussed above, variation is mainly in aperture number and arrangement. The wall structure is constant, but corrosion often results in a pitted or scabrate surface. Comments: It would be possible, on the base of aperture configurations to split this pollen type into a large number of species, but, since these smaller groups have no restricted ranges, they are united here under one large polymorphic species. Distribution: In the Caribbean area occurring from the base of the Verrucatosporites usmensis Zone upwards, in Nigeria known from the middle part of the Verrucatosporites usmensis Zone upwards. Unknown from Borneo. Taxonomic affinities: This very peculiar pollen type is so far known only from Malpighiaceae. The pollen grains of the following genera correspond best with 344
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the fossil species: Brachypteris (Plate XVIII, 12), Bunchosia, Hiraea, Mascagnia, Stigmatophyllum, and Tetrapterys. The pollen grains of the Malesian genera of the Malpighiaceae do not belong to this type.
Class Syncolpatae IVERSENet TROELSSMITH,1950 Genus Striasyncolpites nov. gen.
Derivatio nominis: Named after striate ornamentation and syncolpate apertures.
Diagnosis: Oblate, tricolporate; colpi connected at poles, pores protuding; wall thin, finely striate, generally coarser at equator. Type specimen: Striasyncolpites zwaardi nov. sp. Comments: Identical with the pollen type in Cuphea (Lythraceae). Striasyncolpites zwaardi nov. sp. (Plate XVIII, 9; holotype) Derivatio nominis: Named in honour of Mr. A. L. P. Zwaard in recognition of his contribution to Nigerian palynology. Holotype: Slide TC-169, surface sample HO-24, Trinidad. Description: Single grain, radially symmetrical, isopolar, oblate; outline in polar view rounded triangular. Tricolpate, colpi ectexinous, connected at poles; pores endexinous, small, protruding over a distance of 2 #. Endexine < ½/z thick; columellae < ½ # thick and long; tectum < ½/z thick, striate in meridional direction; striae ½/z wide, ½/~ apart, coarser at equator. Dimensions: 16-23 #. Variability: Mainly in coarseness of striate sculpture. Distribution: Only known from the Caribbean area, and restricted to the Echitrieolporites spinosus Zone. Taxonomic affinities: This pollen type is only known from the genus Cuphea (Lythraceae). Especially close are C. aequipetala (Plate XVIII, 10), C. pinetorum, C. platycentra, and C. wrightii. ACKNOWLEDGEMENTS In the compilation of this paper the authors were able to draw on the accumulated experience of a large number of colleagues, whose assistance and criticism is gratefully acknowledged here. Thanks are also due to the Management of the Bataafse Internationale Petroleum Maatschappij and the Shell-BP Petroleum Development Company of Nigeria Ltd. for permission to publish this paper,
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to Creole Petroleum Corporation and Mene Grande Oil Company (Venezuela) for allowing the publication of well data received in exchange, and to Prof. Dr. C. G. G. J. van Steenis (Leiden) for critically reading the manuscript.
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