Biostratigraphy and palaeobiogeography of East Africa and the Iberian peninsula

PglAE0ELSEVIER

Palaeogeography, Palaeoclimatology,Palaeoecology112 (1994) 297-322

Biostratigraphy and palaeobiogeography of East Africa and the Iberian peninsula. Martin Pickford a, Jorge Morales b " Geological Survey ofNamibia, P.O. Box 2168, Windhoek 9000, Namibia b Departamento de Paleobiologia, Museo Nacional de Ciencias Naturales, Josk Gutidrrez Abascal, 2, 28006 Madrid, Spain

Received 26 July 1993; revised and accepted 20 April 1994

Abstract The aim of this paper is to examine the mammalian faunas of the Neogene of Spain and of East Africa with a view to understanding the relationships between the Neogene faunas of the two regions. The available data indicates that during the Neogene, faunal similarities between Iberia and East Africa varied greatly, at times the resemblances being relatively great (high number of genera in common), at others the similarities being weak (low number of genera in common). Changes in faunal similarity appear to be related to latitudinal fluctuations in the position of the boundaries of the Proto-Ethiopian and Proto-Palaearctic zoogeographic realms. Periods of greater faunal similarity coincide with a northerly position of the boundary zone, while periods of greater faunal dissimilarity occur when the boundary zone is located in a southerly position, as it is today. We related these changes in the position of the boundary zone between zoogeographic realms to geotectonic, climatic and astronomic changes which affected the globe.

1. Introduction Biostratigraphy and palaeobiogeography use the same data base: fossils. The former discipline accents the time dimension whereas the latter concentrates on the space dimension, but both are interdependent to a great degree, since each depends upon comparisons of palaeobiological data sets from two or more areas and time periods. One often sees in the literature discussions on biostratigraphic correlations within an area, a limited time period or a single m a m m a l group (see Azzaroli et al., 1988 and Thomas, 1984 as exampie), but seldom does one see a close comparison of the palaeobiologic histories of two or more regions that lie within different biogeographic realms. This is understandable when one considers that in general, the faunal similarities between different biogeographic realms tend to be weakly 0031-0182/94/$7.00 © 1994 Elsevier Science B.V. All rights reserved SSDI 0031-0182 (94) 00042-7

expressed, making faunal comparisons lean or difficult. However, some groups of large mammals, such as carnivores, tend to be cosmopolitan and therefore occur in several biogeographic realms, providing possibilities for faunal correlation. But of more interest is the observation that biogeographic realms are dynamic entities. Their boundaries are not geographically fixed and neither are their faunal contents rigidly confined within them.

2. Biogeographic background Boundary zones between biogeographic realms are precisely that: zones. They are l e a k y - - a n i m a l s and plants can and do cross from realm to realm, especially over geological time s p a n s - - a l t h o u g h the bulk of taxa within any particular realm appears to remain faithful to that realm. Over geological time spans, boundary zones between biogeographic realms shift about on the surface of

298

M. Pickford, J. Morales/Palaeogeography, Palaeoclirnatology, Palaeoecology 112 (1994) 297-322

the globe, the principal displacement vector being latitudinal. This is because the primary signal in biogeographic realms is itself latitudinal in origin, the realms being biological expressions of two factors, both of which are due to Earth/Sun relationships. Firstly, because the Earth is a rotating sphere that orbits round an energy source--the Sun--there is differential receipt of solar energy at the earth's surface, maximum quantities being absorbed by each square meter at the equator and minimum quantities at the poles of rotation. Secondly, because the axis of rotation of the Earth is inclined at a steep angle to its orbital plane, the zone of maximal receipt of solar energy shifts latitudinally on the surface of the globe. As the spinning Earth orbits round the Sun, alternatively its north pole or its south pole are leaning towards the Sun. Maximal receipt of solar energy in the northern hemisphere occurs when the north pole of rotation is facing towards the Sun, whereas maximal receipt of energy in the southern hemisphere occurs when the south pole of rotation faces towards the Sun. These annual latitudinal shifts in the position of maximal energy receipt at the Earth's surface are responsible for the phenomenon of seasonality. In high latitudes, temperature and day length fluctuations are the strongest signals to emerge from the myriad of seasonality signatures that exist. Humidity fluctuations occur but are generally less marked. Thus seasonality in high latitudes is overwhelmed by day length and temperature changes, the seasons alternating predominantly between cold (winter) and hot (summer) (Fig. 1). Many plants and animals show primary adaptations to cope with such fluctuations. Highly mobile species such as birds and bats have evolved migratory behaviour, the migrations being triggered by changes in day length. Less mobile species such as polar bears and arctic hares have evolved hibernation behaviours, which are also triggered by day length changes. In general, in the high latitudes,reproduction is timed to coincide with the warmer-summer and autumn--periods. In low latitudes in contrast, day length and annual temperature fluctuations are minor, but humidity fluctuations are usually important, with the result that seasonality in the tropics tends to be dominated by wet/dry alternations (Fig. 1). Many animals living

in the tropics have evolved strategies to cope with such wet/dry seasonality. Some species aestivate and many of them time their reproduction to coincide with the onset of wet seasons. Animal species attempting to cross from a tropical to a boreal zone or viceversa may physically be able to do so, but they seldom survive there unless they can change their reproductive strategies to coincide with the type of seasonality which characterises the regions which they are colonising. As individuals, zoo animals, for example, appear to do quite well if properly looked after, despite the very different seasonality that can occur in their foreign homes. What they are unable to do unless special care is taken on the part of the zoo keepers, is to maintain their numbers by reproducing. It is a difficult matter for a specie to change its reproductive cycle to coincide with a cold/warm cycle if its primary adaptation was to a wet/dry cycle. This is because timing of reproduction in boreal species is often triggered by day length changes which are read by the pineal gland which in turn triggers hormonal controls within the body. Reproduction in wet/dry seasonality regions are triggered by humidity levels, food abundance and food type among others. Species that occur in several zoogeographic realms--pandemic to cosmopolitan taxa--such as many kinds of carnivores, tend to be reproductively flexible and their food sources are much the same in the different realms. Species which are confined to single zoogeographic realms--endemic taxa--are often herbivores with reproductive cycles closely tied in to wet/dry or cold/warm seasonality, as the case may be. Furthermore, because of the major differences between tropical and boreal plant communities and biomass productivity through the year, herbivore communities often show a marked latitudinally controlled distribution pattern. The most obvious example of this phenomenon is the boundary zone between the Oriental and Palaearctic realms in South East Asia. Here there are no physical geographic barriers to keep the Palaearctic and Oriental species apart. Instead, it is the major difference in kind of seasonality that does so hot/cold to the north of the boundary zone, wet/dry to the south of it. For these and other reasons, species tend to remain within their biogeographic realms, some of

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them even over geological time periods. But because the boundary zones can and do move and because not all lineages are strictly confined to their realm, specific areas of the globe can experience faunal changes which implicate species from neighbouring biogeographic realms. Occasionally in the geological column, one may note a period during which there was a relatively large number of new lineages colonising a region from an adja-

cent realm, at other times fewer. For example, if the Ethiopian genus Hippopotamus occurs in a deposit in Europe, it is often found alongside other Ethiopian taxa such as hyaenas and lions. Such colonisations of regions which are normally Palaearctic by essentially tropical species are usually of short duration, with the tropical species soon going extinct in their high latitude home. However, some lineages do manage to adapt to

300

M. Pickford, J. Morales/Palaeogeography, Palaeoclirnatology, Palaeoecology 112 (1994) 297-322

conditions in their new regions so well that they become intimate elements of their new realm. The woolly mammoths and rhinos of the Pleistocene of Eurasia represent such lineages, but even these species did not last at high latitudes for extended periods of geological time. Understanding the dynamics of such invasions and extinctions is greatly enhanced if the fossil records of neighbouring zoogeographic regions are well documented. Comparisons between the faunal histories of the two such regions can yield substantially more evidence of the details of the processes and timing of faunal interchanges than can parochial examinations of faunal history carried out in each area in isolation from the other. The reliablity and viability of long distance biostratigraphic correlations greatly depends upon the completeness of the faunal successions being compared. While a few "key" taxa, such as the equids Anchitherium, Hipparion and Equus have traditionally been considered to define useful biostratigraphic datum events in the Old World, it is generally accepted that entire faunas provide a more acceptable sense of correlation, because the spread of individual taxa across vast geographic distances containing varied biotopes, can be markedly diachronic. In this study we compare late Neogene faunas from two relatively compact parts of the Old World, Spain (___ 40°N latitude) and East Africa (+ Equatorial), which have been well studied and which have yielded comparatively complete successions of mammalian faunas. Microfaunal remains have proved to be inadequate for the purposes of correlating between East Africa and Spain, on account of their rarity in most of the East African fossil collections. Furthermore, the few East African sites rich in micromammals contain taxa which have not been recorded from Spain, indicating that the zoogeographic ranges of micromammals tended to be more restricted than were those of large mammals, many of which occur in both study regions. 3. Data base

The data upon which this study is based consists of the large mammal fossils recovered from numerous localities in East Africa and Spain spanning the time period 22.5 Ma to the Holocene. A deep personal knowledge of the East African (MP) and

Spanish (JM) Neogene faunas, together with a good knowledge of the faunas of other regions of the Old World and the sites from which they came means that the authors are pooling extensive geological and palaeontological personal observations made over the past two decades. Most of the fossil taxa mentioned here have been examined by the authors in the belief that this is the only really solid foundation upon which to base biostratigraphic correlations. Uncritical garnering of species and generic names from published sources is fraught with problems and quickly renders synthetic works based solely or predominantly on the literature, doubtful to worthless. In East Africa, MP has examined over 500 fossil localities which have yielded in excess of 100,000 fossils spanning the late Neogene and Quaternary periods, belonging to more than 215 genera. In Spain, JM has worked at more than 200 fossil sites and has examined approximately 60,000 fossils belonging to more than 185 genera. In total, some 365 genera are included in this study (Table 1). In East Africa and Spain there are about 73 and 21 extant large mammal genera respectively (numbers vary from author to author). The figures for fossil genera look reasonably complete by comparison, although there is little doubt that new discoveries will be made in both regions. In addition, both authors have visited numerous museums in Europe, North America, the Indian Subcontinent and Africa for the purposes of making comparative studies of fossils. A further point which we consider to be important in biostratigraphy, is that both authors have studied several different groups of mammals in depth and thus have a first hand knowledge of several of the biostratigraphically important groups and a good working knowledge of the overall faunas for the time periods and regions being studied. Table 2a-g are lists of taxa examined together with their known distribution in time within Spain and East Africa. While it is evident that there are some gaps in our knowledge, it is clear that the data base is sufficiently comprehensive for the purposes of this review. Figs. 2 and 3 provide the chronological positions of the main localities which have yielded fossils in East Africa and Spain. The East African sites are in many cases positioned on the basis of radio-isotopic dating, stratigraphy

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994) 297-322

301

Table 1 Generic diversity and main zoogeographic atfmities of the Neogene large mammal families from East Africa and Spain Family

Spain

Arctocyonidae Teratodontidae Hyaenodontidae Amphicyonidae Canidae Ursidae Mustelidae Nimravidae Viverridae Hyaenidae Cryptoproctidae Felidae Hominoidea Cercopithecidae Lorisidae Proboscidea Deinotheru'dae Hyracoidea Orycteropodidae Manidae Chalicotheriidae Rhinocerotidae Equidae Tapiridae Cainotheriidae Anthracotheriidae Tayassuidae Hippopotamidae Suidae Sanitheriidae Camelidae Tragulidae Moschidae Palaeomerycidae Cervidae Climacoceratidae Giraffoidea Bovidae Eotragini Boselaphini Bovini Hippotragini Hypsodontini Neotragini Antilopini Tragelaphini Ovibovini Caprini Cephalophini Reduncini Alcelaphini

0 0 1 8 4 8 22 2 5 11 1 15 4 4 0 7 2 1 0 1 4 10 3 2 1 1 5 2 9 0 1 1 6 4 20 0 4 24 1 5 4 2 0 0 4 0 4 4 0 0 0

Both 0 0 1 2 2 2 4 0 3 3 1 5 1 1 0 5 2 0 0 1 2 3 2 0 0 1 2 2 3 0 0 1 1 1 0 0 1 2 0 0 0 1 0 0 1 0 0 0 0 0 0

E Africa

Main zoogeographic affinities of family

1 1 7 2 8 2 15 0 21 6 3 7 15 13 4 14 2 8 3 1 3 8 2 0 0 4 2 2 15 2 I 2 1 1 0 2 7 44 0 4 5 5 I 7 5 2 1 0 3 4 7

Not clear Ethiopian Tropical Palaearctic Cosmopolitan Palaearctic Palaearctic (cosmopolitan) Palaearctic Tropical Tropical (cosmopolitan) Not clear Cosmopolitan Ethiopian Ethiopian Ethiopian Tropical (cosmopolitan) Tropical Ethiopian Ethiopian Tropical Cosmopolitan Cosmopolitan Cosmopolitan Tropical Palaearctic Tropical Palaearctic Ethiopian Cosmopolitan Tropical Cosmopolitan Tropical Palaearctic Palaearctic Palaearctic Ethiopian Tropical (Ethiopian) Cosmopolitan Not clear Tropical Cosmopolitan Ethiopian Palaearctic Ethiopian Tropical Ethiopian Palaearctic Palaearctic Ethiopian Ethiopian Ethiopian

302

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology112 (1994)297-322 91

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M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994) 2 9 7 - 3 2 2

Table 2 Generic list of large mammals from East Africa and Spain (empty bar=records in Spain; striped bar=records in East Africa; black bar=overlapping records in Spain and East Africa). (a) Arctocyonidae, Teratodontidae, Hyaenodontidae, Amphicyonidae, Canidae, Ursidae, Mustelidae (8)

2524232221201918171e151413121110

S 8

'7 6

4

3

2

1

MaCTOCYOe411~E rERATODONTIONE TgrModon !HYIM~X~ONTII~E Hy~nm#ounJm~ t o ~ w t u m ) M ~ IlPohyaw)oak)n MAWnopa

l

l

L~dmytlwtum

~

E

v~ xor~-~f~ c~ m

m

= = ~ u m

WAlfftlt.I)l~ LUO~ EonmWvora MeEvora K~lurra SNaonyx Toro~tra Er.~r~don Lutra Paraonyx Aonyx Pa~oomem Prom~

R

P ~ ~4~ Mum~ k:~x~yx

mm~ Mk~k~ Propu~ Toxodon Ck'cammm~ MaraCa Troahar~m #Jer~k Isahyr~#s S#nocyon Prapo~Vo~

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994) 297-322

305

Table 2 (continued) (b) Nimravidae, Viverridae +Herpestidae, Cryptoproctidae, Hyaenidae, Felidae lot

25242322212019181?16151413121110

9

8

7

6

5

4

3

2

1

0i

Ne4RAW)AE Pmunmmo~r~us VNERRIDAE Lel~te~a Kk~ch/* Leptopt~ct~ Herp~des Kanultes Herpmt~ Vlverrm Clvettlctls Atl~x Croe~vchul Ook>~m

imm

Genetta Nm~Vn~

ta~zl imm

Pseudocivetta Seml~K~ Siva~ua Mungo¢ CRYPTOPROCI1D~ P~,~uta HYAEae~E Pflovlvelrops Proflctltherlum Ictttllertum TtWauCt~ Lycyaena Uym~c~ btyperhyaena Adcrocuta H),Nna Grocuta Pachycrocuta Ctw~m~pormetN ProW~e FBJDAE Afrosmtlua

=:::=

c~m

Stena#urus Panthera Homotherlum Megmntereo¢l Dhlofe~ Felm VlretWlurus ~ n a Lynx Pseuaaelurus Panun#cha/mdus Ma~Wrod~

and biostratigraphy. Many of the Spanish localities have been positioned with reference to the European Land Mammal Zonation (MN Zonation) which is essentially based on biostratigraphic arguments, but which is Spain is often founded on knowledge of stratigraphic position

-i

and superpositional sequences of strata.

order

within

measured

4. Terminology There are various "key" words which commonly crop up in biostratigraphic studies, but which are

306

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994) 297-322 Table 2 (continued) (c) Hominoidea, Cercopithecidae, Lorisidae, Proboscidea, Icl ~iAm Cmuzelli PIIopithecus Mlcroplth~us Limno~us Kalepithecus Turkanaplthecus Xenoptrhecu8 DenoYoplrhecus Procor~ul Rangwaplthecus Kenyapithecus Atropltt~us Oryqe~t~cus Otavlplri~cus Nyanz~o~us Aus~,alopithecus Paranthrop~ Homo

2 5 2 4 2 3 2 2 2 1 2 0 1 9 1 8 1 7 1 8 1 5 1 4 1 3 1 2

Deinotheriidae 1

1

1

0

9

8

7

6

5

4

3

2

1

0

m m

~cn c~

ID

Prohylobatw Vlctorlaplthecus Mlcrocolotxm Paracolobus Dolicho~thecus RNnocolot~s Colobu¢ C~,coplthecoides Macaca Patapapto Cecoce~ Dlno~thecus Papio Parado#chol~thecus ~ u s

ac~

c~

LORBDI~ Mloeuotlcus Komba PRC~C~DEA MI~TODONT~DI~ Gomphotherlum P ~ Archaeobelodon Z~oSop~odon E ~ n Prolanancus Choer~opl~don Tetralophodon Anancus S ~

i

~e'.~.;.~:.~,

B.EFHNCnDAE Stegotetrabel~lcn P~m~ep~ Mammuthus B~oh~ Prodelnothe#um C.,;,,.~;~,,~um

imprecise or which convey precision which is unwarranted by the data. In continental settings, the word "datum"-- as for example used when describing the earliest known record of Proboscidea or of Hipparion in Eurasia as the "Proboscidean datum" and the "Hippariondatum"--has misled more than

it has helped biostratigraphers. Seldom does the earliest known record coincide with the arrival time of a taxon in a region: it is almost always later than it. Thus "datum" implies a precision that is effectively seldom attainable. The words "appearance" and "disappearance" likewise imply a precision

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994)297-322

307

Table 2 (continued) (d) Hyracoidea, Tubulidentata, Pholidota, Chalicotheriidae, Tapiridae, Rhinocerotidae, Equidae ~O~

25242322212019181716151413121110

9

8

7

6

5

4

3

2

1

0

Megalohyrax Bunohyr~x P~apllohyrar PIIohyrax Heterohyrax Glgantohyrax Procavla

o~o~yrax ~ A T A

Myoqcteropus Leptoq~pus PHOLIOOTA Man~ (~J MInBIOO/ClrYI.A ~ I D A E PhylloP,#on Moropus Chalicotl',etium Chemosit~

q

T.aPIP~DAE Prc~Aolrus T~olrus ~ O A E Protaceratherium Brachypott~rlum Ple#lacerathertum I-~ro~nto:hinus

Htspanotherlum Kenyatherlum Aceratherium Lartetotherlum GB~ldatherium Dicemn~nus Chilothettdlum Paradlceros Coelodonta Ceratotherium • D;cw-~ Anchltherlum H~opar~n ( s O

which can seldom be confirmed, but which are often proven inaccurate. Combinations of these words such as FAD (First Appearance Datum) and LAD (Last Appearance Datum) are to be avoided in our opinion. The widespread acceptance of the concept of the "Hipparion datum" at 12.5 Ma (Berggren and Van Couvering, 1974) and the "Proboscidean datum" (Madden and Van Couvering, 1976) delayed real advances in Old World large mammal biostratigraphy for more than a decade. We prefer to use the phrases "Earliest Known Record" and "Latest Known Record", since these terms recognise the fact that increase in knowledge of the fossil record generally leads to changes in its understanding and interpretation. Furthermore,

EKRs and LKRs apply only to the specific areas under study, since the concept accounts for the fact that the biogeographic spread of taxa can be diachronic. Thus the EKR of Hipparion in Spain may be synchronous with its EKRs in East Africa and in Pakistan, or it may not be. The question can only be resolved by additional evidence which avoids the trap of circular reasoning. We have worked at the generic level where possible, since there is greater confidence in identifying taxa to this level than there is in trying to work at the specific level. What we lose by excluding the species rank, we feel that we recuperate by working with greater confidence at the generic rank. Furthermore, the number of species shared by Spain and East Africa is limited, whereas the

308

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994) 297-322 Table 2 (continued)

(e) Cainotheriidae, Anthracotheriidae, Tayassuidae, Hippopotamidae, Suidae, Sanitlaeriidae, Camelidae 2524232221201918171e151413121110

9

8

7

6

5

4

3

2

1

0

Nmrlo~ Cm~,;;m;,im Bra~yodus

S~ameq~x Atromeryx Lmpx~munm TAYASSUIDAE T m o Palaeochoerus Xenohyus Scldzod/menm PIPPOPOTI~VIDAE Kenyapommus Hex,pro~don H~po~mus SUDAE Hyotherium Aurellachoen~ NgURIWO Kenyasu# t ~ "Bunol~odon" L~triodon L ~ Conohyus Parachleuastoct)oerus Nyanz~/~eruJ Nomctmenx Propotamochoer~ (Korynochoerus) Mlcrootonyx

~

II::m,

mm~alaml~! T

m ~

Potsnocho~'zm Kmpochowus MirkzYoct',oems Pl~coct~mw

C~¢IELIO~E Paracam~us Came/us

number of genera common to the two regions is significantly greater. 5. Faunal overlap between Spain and East Africa We have produced charts of mammal genera that are known to have occurred in both Spain and East Africa. Counts have been made at 0.5 Ma intervals, which is about as fine a resolution that one might expect to be able to obtain from the data. Counts at 1 Ma intervals smooth out the peaks slightly, but the signal still shows through, suggesting that the peaks are real observable entities and not just random patterns. These overlap peaks are independent of overall known generic diversity. For example, today there are only five genera common to Spain and East Africa, despite

the fact that over 80 genera exist in the two regions. The overlap peak of 8 genera at the onset of MN 04 is a period from which 78 genera are known. The overlap peak of 9 genera at MN 09 occurs when only 65 genera are known in the fossil records of the two regions and the peak of 11 genera at MN 13 occurs when only 63 genera are known. Conversely, the generic diversity peak in East Africa between 12-13 Ma from which 57 genera are known from the two regions, coincides with an overlap of only 4 genera. During the Miocene the number of genera common to Spain and East Africa fluctuated between 1 and 12. High overlap figures indicate that the two regions had become more similar in biogeographic terms, whereas low overlap indi-

M. Pickford. J. Morales/Palaeogeography. Palaeoclimatology. Palaeoecology 112 (1994.) 2 9 7 - 3 2 2

309

Table 2 (continued) (f) Tragulidae, Moschidae, Palaeomerycidae, Cervoidea, Climacoceratidae, Giraffoidea 252423222120191817161514131211101 Dorcalmm~Jm hYam~h~

9 8 7 6 S 4 3 2 1 0~

[z3

MOSCI'IDAE Amphro-~u/us

,

, =

DrmoUw~um (WsW~m~) ~rorne~/x

=

Oriomeryx

TY.a;.-~.7~.ix LJooml,yx P ~ PA~opan)~4m~ Aclooawnaa

SDh#noawlm Euprox AnWUmox L ~ T ~ C ~ Co-vt~ OotkCaoaoacmw R ~

Dama Atvlmloaer~ Eu~docer~

Cllnmaoauaw ;¢mua,,~4yX Lorancamwyx ~meryx

=

Pam~traQw De~nna~w~rn itx~zm. =

Sk~a~nerium Glraffa

cates that they had become more dissimilar. From the lower Miocene until the present there were four main peaks of high overlap, separated from each other by troughs of low overlap (Fig. 4). High overlap peaks occur in the lower Miocene (MN 04), the late middle Miocene (MN 7/8), the latest Miocene (MN 13) and the late Pliocene (MN 17). Overlap troughs occur prior to MN 04 (which may be due to the poor nature of the fossil record in Spain), in the middle Miocene (MN 05), the late Miocene (MN 10), the Pliocene (MN 15) and there is a drop in overlap figures during the late Pleistocene to Holocene. A count of cervid diversity in Spain (Fig. 4)

even though the diversity is always rather low, reveals a trend which is generally out of phase with the overlap chart. For example, when the overlap peak at MN 04 occurs, the diversity of cervids drops from 2 to 1. As the overlap figures for the upper Miocene and early Pleistocene drop, the diversity of cervid taxa increases from 1 to 3 and from 1 to 5 taxa, respectively. We interpret this to mean that the Palaearctic influence in Spain, as measured by cervid diversity, was fluctuating and furthermore, that the Palaearctic influence generally decreased when the Ethiopian influence increased and vice versa. The presence of crocodiles in Spain has also

310

M. Pickford, J. Morales/Palaeogeography,Palaeoclimatology, Palaeoecology112 (1994) 297-322 2

Table

(g)

(continued)

Bovidae

25242322212019181716151413121110

9

8

7

6

5

4

3

2

1

0

BOVIDAE

Eotragu~ Mio~ms Protragocetu~ AuMropc~tax Tragoportax Siv~ea8 Kipslgicerus Tragore,u Palaeor~s MNembri:,~ax P ~ Ugandax Slmatherium 8rabovus Synceru$ Pelorovi$ Bos/Bison S~lrgel~a Tethyfragus G~mt~agus Protoryx/Pachytragus Praedamalls H~opotragus Oryx Hypsodontidae Gazella Oioceros Homolo~ H~oanodo¢~

~Yg

ID

gnta

r

mE~

Gazelloeplra Antidorcu

AnU~pe L#ocr~#us Trm~l~ol~us F~urotragus Samom~ Hesperi~ Pmeo~ P ~ PR~amptoceros Bupi~pra Caprm Cephaloph~s Philantomba Syivk~pra Madoqua Rnynchotragus Or3otrag,;~ Neotragus

Em

a=

Pelea

Domatragus Raphtcwo* Ko~us Menellkla ThaWoce~

Redunca Alcelaphus Megalotragus Beatragus Pannularius Pamstigorgon Connochaetes

Dillah~m

been plotted in Fig. 4 and these periods coincide closely with the mammal overlap peaks, providing further evidence of the existence of periods during which conditions in Spain were more tropical than they are today.

The combination of data suggests that the boundary zone between the Palaearctic and Ethiopian biogeographic regions was shifting latitudinally during the Neogene (Fig. 5). At the onset of MN 04 this boundary is thought to have shifted

311

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994)297-322 0 Q5 1

•

6

Q4

2 MN 1

3

12

? 4

5

MN

10 9

PVI]

W

6

7

9 t0

7

tl

MN

12 13

6

15

5

PV[

PV

5

4

8

,5

12

t4

3

C8

ti

t3

2

PVII

MN 13

7

11

c3

C7

5

tC

I

c6

5

MN t,

9

C2

c5

4

8

0

C4

16 15

6

CI

PI~

2 2

t4 15

p'rtr tE

16

MN

4 17

P]~

t7

t8

p1T

18

t9 P1 2(

MN

ZC

3

2t 2;

2b

2~

2a

2~

MN I

2~ Mo

19

PO

9 ? LARGE MAMMALS OCCURRING IN BOTH SPAIN 8= E. AFRICA (N ° of Genero}

DISTRIBUTION OF CROCODILES IN SPAIN

S PAl N

2t Z2

CERVID DIVERSITY IN SPAIN (N ° of Genera)

Z3 24

2~ E. AFRICA

Mo

Fig. 4. Large mammal taxa occurring simulaneously in Spain and East Africa, the occurrence of crocodiles in Spain, and changes in diversity of Cervidae during the Neogene of Spain. northwards. It then shifted southwards during M N 05, northwards again at M N 7/8, southwards at M N 10, northwards at M N 13, southwards at M N 15, northwards at M N 17 and southwards again

during the late Pleistocene. As a result the biogeographic affinities of Spain fluctuated between purely Palaearctic (as it is today) and partly Ethiopian (as it was during M N 04 for example).

312

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994) 297-322 22

21

20

49

18

17

16

15

t4

t3

12

I1

10

9

8

7

6

5

4

3

2

~

0

Mo

=|

~

Boundory zone in northerly

position

Boundory

/-/~a~-/.~-'R. ~ .~.~..~*~v,&

zonel 7P/~','~_~;;,X'~

in southerly

l// ~ 2 1 ~ ~

90 °

80" ~ ' "

90ON

' ~

60 °

PALAEARTIC

BIOGEOGRAPHIC

80* 60 °

REALM

50"

50 °

,o.

,o.

,o.

v - -

-

200

ETHIOPIAN

,oo

BIOGEOGRAPHIC

20 •

REALM

m

M 22

21

20

t9

llll t8

17

t6

15

14

t3

II 12

1t

10

9

8

7

6

5

" lll H 4

3

2

1

0 Mo

Fig. 5. Latitudinal fluctuations of the boundary zone between tropical and boreal biogeographic realms during the Neogene.

At present the boundary zone between the Palaearctic and Ethiopian zoogeographic realms lies at a latitude of about 30°N. It crosses Africa in an east-west sense some distance south of the Maghreb and the North African littoral zone, both of which are in the Palaearctic Realm (Geraads, 1982). Northwards shifts appear to have been rather sharply expressed, while the subsequent southwards shifts seem to have been gradual. During periods of high generic overlap between East African and Spanish faunas, we postulate that Spain lay within the northern parts of the Ethiopian Zoogeographic realm (Fig. 5) or at least within the boundary zone, which is about 10° of latitude wide (Fig. I), the Palaearctic Realm lying some distance north of Spain. During the generic overlap troughs, Spain is considered to have lain within the Palaearctic Zoogeographic Realm, the boundary zone lying somewhere in northern

Africa. By this means the Iberian Peninsula experienced greater or lesser affinities with the Palaearctic or the Ethiopian Realms, with the consequence that its zoogeographic faunal content fluctuated, sometimes having greater Palaearctic representation and lesser Ethiopian influence, at other times having the contrary. Geraads (1982) described much the same fluctuations in the Miocene to Recent faunas of the Maghreb. Van der Meulen and Daams (1992) reported that there was a major change in Iberian rodent faunas at the onset of MN 04, which accords with the large mammal changes.

6. Generic diversity and earliest known records

Fig. 6 provides a count of the diversity of large mammal genera recorded in Spain since the lower

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994)297-322

Miocene. The vivenfds and mustelids have been omitted on account of their very variable fossil representation. Diversity has fluctuated between 16 and 40 genera, diversity peaks occurring at MN 04, MN 09, MN 13 and MN 17. Diversity troughs occur at MN 05, MN 11 and MN 14. Some of the variation is undoubtedly due to vagaries of the fossil record, but a consideration of Wallace's Rule (Pickford, 1990) suggests that diversity peaks coincide with increased tropicality, while troughs coincide with increases boreality. This appears to be the case in the sense that the diversity increases in Spain occurred during periods when Iberia seems to have lain within or close to the Ethiopian Realm, whereas the troughs occur in the record when Iberia was part of the Palaearctic Realm. In many instances it is clear that mammalian lineages were entering Spain from neighbouring regions, since there are no likely ancestors for such lineages in the prior Spanish fossil record. Dryopithecus, Pliohyrax and Hexaprotodon represent such immigrants from Africa, while Anchitherium, Hipparion, Equus and Paracamelus represent immigrants from North America. Fig. 7 reports the known generic diversity changes in East Africa during the Neogene and Quaternary. There is a general trend of decrease in generic diversity during the Miocene, with important increases during the Pliocene and Pleistocene. These figures are undoubtedly biassed by the spotty nature of the fossil record in East Africa (Fig. 1) for much of the Miocene. However, well sampled groups, such as the herbivores and primates, show similar trends (Pickford, 1991), suggesting that the form of the curve is informative, even if the precise figures are perhaps less so.

7. Discussion

Patterns which emerge from the data indicate that during the past 22.5 Ma there were at least four major periods of marked faunal change in both Spain and in East Africa. These involved so many genera that the phrase "faunal turnover pulse" springs to mind. While there is some margin for error and the resolution is not very great in the dating techniques (-t-0.5 Ma), it appears to us

313

that the pulses were virtually contemporaneous in the two regions. They occurred at about 18+0.5 Ma, 11.5+0.5 Ma, 7.0+0.5 Ma and 2.5+0.5 Ma ago. A smaller peak of faunal change occurred at about 8.5 Ma. In Europe the major pulses correspond to faunal zones MN 04, MN 7/8 and 9,MN 13 and MN 17, while the minor one corresponds to Zone MN 11. Comparison of these results with studies of faunal change elsewhere in the planet, reveal some interesting correspondences. For example, in a study of the fossil genera of the Great Plains of North America, Alroy (1992) reported major diversity drops at 17.4 Ma, 11.6 Ma, 8.7 Ma and 6.5 Ma in faunal successions dated mainly by radio-isotopic techniques. His analysis did not include late Pliocene and Pleistocene faunas. The number and timing of these faunal changes in North America are surprisingly close in number and timing to those of Iberia and East Africa, suggesting that they may well be related to responses to some global scale changes of some sort. Barry et al. (1985) and Barry et al. (1991) studied faunal turnovers in the Siwaliks successions of Pakistan and have reported that significant faunal changes occurred at 16-20 Ma, 9.5 Ma and 7.4 Ma and minor changes at 13.2 Ma and 12.0 Ma, based on fossils collected from sedimentary sequences correlated to the Geomagnetic Reversal Time Scale. Considering the differences in dating techniques and the geographic positioning of the regions studied, we find that the correspondences are remarkably close, both in number and in timing, with one exception (Fig. 8). The apparently large offset between the 11.5 Ma event in Iberia/East Africa and the 9.5 Ma event in Pakistan may well be an artefact of the dating methods employed rather than a real chronological offset. Both of them include the earliest records of the equid Hipparion in their respective areas and in other respects these two faunal turnovers resemble each other. Whether it is the Pakistan dating which requires amendment, or that of the rest of the world, or both, remains to be resolved. In the Iberian and East African fossil sequences, we do not observe the minor events at 13.2 Ma and 12.0 Ma that Barry et al. (1985) reported from the

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994)297-322

314

N° of Genera ,.0 2 4 6 8 t0 t2 t4 t6 18 20 22 24 26 28 30 32 34 36 38 40

Ma

io C1

0

1

C2

1

2

C3

2

3

4N17 ~N 16 I(

I

C4

2

IN 15

C5

IN14

c6 C7

4 5

6

MN 13

7

8 9

=

12•7 /

C8

=

P'VI

PY KNOWN GENERIC DIVERSITY LARGE MAMMALS OF SPAIN (less Viverridoe and Mustelidoe)

14

2

PN

:4 5

plrb

16

6

N2 P~o

17

~ r

18

PI sj, s j'

19 s~ SJ

~N e~

19 PI :0

PO

,3

2a

J~

!5

18

2

2b

MN1

7

LACK OF SITES

%%%%~

Ma

0

3

15

!4

7

I1

13

~.3

6

9 P~

2

P.2

5

8

11

;o

4

p "y]]]

IMMIGRANTS TO SPAIN FROM AFRICA~ ASIA AND NORTH AMERICA

10

3

4 5

SPAIN

E. AFRICA Mo

Fig. 6. Number of genera of large mammals of Spain (except viverrids and mustelids). Immigrations to Spain from neighbouring land masses are indicated.

315

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994) 297-322

MQ 0

'L

12 14 16 18 2 0 2 2 2 4 2 6 2 8 _

MQ

5032343838404244464850525456586062646668

~._---..-.~

6:

-"- ~C~--

t 2 2 2

2 3

2

Ct

3

C5

4 ~

7

~NoWN GENERIC DIVERSITY OF LARGE MAMMALS OF EAST AFRICA

5 6

CE C7 = p'y~ C8

7

8

0

4 5

6 7

t2

8

9 MN lO

P',~K

I0

9 0

It t2

7/8

PV 3

14

Pt~

MN AN~5

r5

IMMIGRANTS TO EAST AFRICA FROM EURASIA AND N. AfdE

16

17

~///////////////~

18

to

"///////~//////////~ tl

4 5

Pint

6 PTffa

7

PIT

8

PT 0 FEW SITES PO

t

2b

2

20

3

MNt Ma

SPAIN

E. AFRICA M o

Fig. 7. Diversity of large mammal genera in the Neogene and Quaternary of East Africa with counts of taxa immigrant from neighbouring and distant continents.

Siwaliks, but this could be due to the restricted number of fossil sites spanning this period in East Africa. Neither is there a clearcut correspondence

for these events in the Great Plains succession of faunas, which are better known. They possibly represent faunal changes of localised significance

316

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994) 297-322

MQ

0 VALACHIAN

---8.5 --.

RHODANIAN

10 •--t2.0-

-

--

ATTIC

t3,2 ---

~5 ~ y ~ t T.4 g~

STYRIAN

20 G R E A T PLAINS SIWALiKS N. A M E R I C A PAKISTAN

SPAIN A N D EAST AFRICA

TECTOGENIC PHASES

Fig. 8. Comparison of major global scale Neogene faunal events reported from North America, Pakistan, Spain and East Africa (Double ended arrows correlate the events). The only major chronological offset is between the Hipparion event of Pakistan and the same event in the rest of the world. This offset is probably an artefact of the dating methods employed, but it is not known whether it is the Pakistan date which requires amendment, or whether it is those from the rest of the world, or both. (Minor events of local or regional significance are dotted).

rather than global scale events which have thus far escaped detection elsewhere. A synthesis of the data from East Africa, Iberia, Pakistan and the Great Plains of North America, reveals that there were several major faunal turnover pulses during the Neogene. Many of the genera involved in these pulses were colonising regions from neighbouring or even from distant zoogeographic realms, suggesting that they were periods of major adjustments to zoogeographic boundary zones. In the case of Iberia and East Africa, the boundary zone between the Palaearctic and Ethiopian realms appears to have been fluctuating latitudinally. Pickford (1986, 1990) has already pointed out that this boundary zone has moved northwards and southwards during the Neogene and that while it is in a northern position, the Ethiopian and Oriental zoogeographic realms fuse into a single entity stretching from Iberia in

the west to China in the east (Fig. 5). While the zoogeographic boundary is in a southern position, as it is today, the Oriental and Ethiopian zoogeographic realms are separated from each other by a wide swath of the Palaearctic Realm in the vicinity of the Middle East and Afghanistan. A further point of interest is that the major periods of faunal turnover in North America, Spain and East Africa (Tables 3-5) coincide closely with peaks of intercontinental interchange of large mammals (Fig. 9). For example, the onset of the Hemingfordian land mammal age in North America was accompanied by an "invasion" of 6 or 7 mammalian lineages from the Old World (Woodburne, 1987). This period correlates closely in time with the onset of MN 04 in Spain, which saw the arrival of 7 lineages from North America and Africa. In East Africa, this period coincides with faunal sets PII and PIII, during which 21 large mammal lineages entered Africa from Eurasia and America. This period coincides closely in time with the Styrian tectogenic phase. There followed several million years with little evidence of intercontinental interchange of large mammals, until towards the end of the middle Miocene when there was another wave of intercontinental transfers, but this time more dispersed through time and involving fewer lineages. These interchanges occurred mainly between about 13 Ma and 10 Ma, which correlates closely in time with the Attic tectogenic phase. After a further period of reduced interchange, there was an abrupt and marked increase at the end of the Miocene. 11 lineages entered North America from the Old World, 9 entered Spain from Africa, Eurasia and North America and 9 entered East Africa from Eurasia and North America. The timing of this episode correlates well with the Rhodanian tectogenic phase. In the Mediterranean area this period of interchanged could have been partially contemporaneous with the Messinian dessication crisis, that can favour the exchanges between Spain and the adjacent areas (Azzaroli, 1990; Azzaroli and Guazzone, 1979). After yet another period during which there was little or no intercontinental faunal interchange, renewed activity started during the Pliocene. 5 lineages entered America from the Old World, 2

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994) 297-322

317

Table 3 Earliest records of mammaliangenera in North America immigrantfrom the Old World (accordingto Woodburne, 1987;datingfromAlroy, 1992)

"o

Bison, Oreamnos, Ovis, Ovlbos, Aloes, Homo, Lutra, Lepus, Marnmuthus, Mustete, Panthers, Soergella, Rangifer, Cervus

Ursus, Parailurus, Chumaporthetes, Lynx

Ochotona, Pleslogulo, Eomelllvora, Slmocyon, Vulpes Indarctos, Agrlotherlum, Falls, Megantereon, Machslrodus, Tap/ms

10 11

Ischyrictis, Arnebelodon, Platybelodon 12 13 14

Gornphotherium 15

Plithocyon 16 17

Mionictls, Pseudaelurus 18 19

Potarnotherium, Arnphicyon, Phoberocyon, Hemicyon, Ursavus, Protaplrus, Brechypotherium 20 21

Cephalogale, Cynelos, Ysengrinia

22 23

24 IVtoropus 25

lineages entered Spain from the New World and from Africa,while 5 lineages entered Africa from Eurasia and America. This and subsequent activity during the late Pliocene and Pleistocene coincides in time with the Valachian tectogenic phase. Pickford (1990, 1991) has suggested that there are two sorts of explanation for latitudinal fluctu-

ations in the boundary zones between biogeographic realms. The most commonly cited explanation found in the literature is that the tropical zone widened and narrowed over time, but that its centreline remained fixed at the present fay equator. This has been called the accordion hypothesis of ecoclimatic belts (Pickford, 1992).

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994) 297-322

318

Table 4 Earliest known records of mammalian genera in Spain immigrant from Africa (#), America (*) and other part of Eurasia

Homo#, Megeceros, Euctenoceros,Dame, Capreolus, Soergelia, Ovibovtni, Bison Crocuta#, Xenocyon, Cuon, Males, Theropithecu$#, Elephas#, Coelodont$, Hippopotamus# Peehycrocuta, Mammuthus, Eucladocero$, Praeovibos, Gallagoral, Procamptoceras Paradolichopithecu$#, Megantereon, Homotherium, Penthera, Enhydricti$, Equus*, Arvernoceros Gazellospira. Hesperidocera$ Ursus. Chasmaporthetes, Acinonyx, Leptobos# Hyaena, Dolichoplthecu$#, Sus Alilepus; Agriotherium, Vulpes*, Nyctereutes; Dinofelis, Fells, Enhydriodon, Macaca# Baranogale, Plesiogulo, Siveonyx, Percrocut$#, Meteiluru$, Canis*, Hexeprotodon# Anancus#, Paracamelus*, Pliocervu$, Lucentia, Croizetocerus, Tregoreas

10 Sabadellictis, Promephitis, Taxodon, Marcetia, Circamustela, Mesomephitis, Proputorius Simocyon, Hyaenicti$, Adcrocuta, Peramachairodus, Schizochoeru$, Microstonyx, Tragoportax 11 Inderctos, Austroportax Pliohyrax#, Tapiru$, Ancylotherium, Dicerorhinu$#, Hipparlon*, Decennatheriurn 12 Plioviverrops, Ursavus, Tetralophodon#, Delnotherium, Protragocerus, Miotragocerus, Barberehyus, Perachleuastochoeru$, Propotamochoeru$,Palaeoplatyceros, Stehlinoceros, Trocharion, Ischyricti$, Dryopithecus# 13 14

Herpestes, Vtverra, Aceratherium, Listriodon, Hispanomeryx, Euprox, Tethytragus, Oioceros

15

Protictitherium. Conohyus, Heteroprox, PIIopithecu$#

16

17 Pseuderctos, Ysengrinie, Hemicyon, Plithocyon, Ibericti$, Semigenett$, Sivanesu$, Cynelos Hyainailourus#, Amphicyon, Prodeinotherlum#, Gomphotherium#, Archaeobelodon#, Chalicotherium# 18 Plesiaceratherium, Prosantorhinus, Hispanotherturn, Lartetotherium, Galndetherium, Teucanamo, "Bunolistriodon', Oorcatherlum#, Micromeryx, Paleeomeryx, Trlceromeryx, Lagomeryx, Eotregus 19 20 21 22

Anchitherium'. Aureliechoeru$. Procervulu$, Acfeocernas

23 24

Haplocyonoide$, Cephelogale, Phoberocyon, Herpestides, Pseudaelurus Menidae. Protapirus, Brachypotherium. Proteceretherium, Brachyodus#, Xenohyu$, Andegameryx, Amphitragulus, Oriomeryx, Dreraotherium, Lorancerneryx

25

Almost never considered is the possibility that the orientation of the ecoclimatic belts shifted with respect to the surface of the planet (Pickford, 1990) but it is nevertheless an idea that has much to recommend it, because it explains many otherwise contradictory observations, or patterns of faunal and floral distribution that cannot be

explained within the accordion paradigm (Pickford, 1992). This has been called the graticule shift hypothesis. Morales et al. (1993) have also deduced that there was a major change in the degree of seasonality at the onset of the middle Miocene and that this change was worldwide. They discussed the possibility that the obliquity of the

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994)297-322

319

Table 5 Earliest known records of mammal genera in East Africa immigrant from Eurasia (#), America (*) and others parts of Africa Ms

0 1 2

Aclnonyx#, Cercocebu$, Beetragus, Phacochoeru$

3

Lyceon, Hyaena, Crocuta, Megentereon#, Homotherlum#, Penthera#. Dinofeli$#, Cheemaporthetee#. Homo Gigentohyrax, Equus', Men.idiochoeru$,Antllope, Menellkie, Pelorovi$. Antldorca$, Synceru$, Megalotragu$ Lutra, Thempithecus, Cercopithecu$, Elephas, Loxodonta, Potamochoerue#, Notochoerue, Cemelue°

4

5 6

7

Hystricidee#. AIIlepus; Ceni$', Vulpes; Viverra#. Enhydriodon#, Ple$iogulo#, Agriotherium#, Hominidee, Perapapio Mammuthus, Stegotetrabelodon, Primelephes, Stegodon, Ceratotheriurn, Diceros, Hexaprotodon, Ceinochoeru$, Sivatherium, Giraffe, Hippotregini, Miotragoceru$#, Bovini, Medoqua, Aepycero$, Tragelaphu$, Alcelephini

8

Elasmotheriini#, Microcolobu$, Anencus, Ancylotherium#, Peleeoraas 9 10

Ictitherium#, Nyanzechoerus

11 12

Hipparion; Libycoseurus. Slvoraas, Eomelllvora Dendromuridae#, Lutrinae#, Tetrelophodon, Pachytragu$#, Protoryx

13

Percrocuta#, Agnotherium#, Hyp$odontldee#, Kip$igiceru$, Gentrytragus, Birgerbohlinia

14 15 16

Victoriapithecus. Pmhylobates, Doliochoerini. SchizochoerinL Kenyapotamidae#, Listriodon#, Conohyus#, Lophollstriodon#, Climacocera$, Nyanzemeryx, Bovidee (2)#

17

18

Kenyalagomys#, Felidae#, Amphicyonidae#, Hemicyon#, Ischyrictis#, Eomellivora#, Dicerorhinu$#. Chllotheridium#. Brachypotherlum#, Sivemeryx#, Afromeryx#. Sanltheriidae#, Canthumeryx, Giraffoidea, Propaleeoryx

19 20 21 22 23 24

Fissipeda#, Chalicotherildae#, Rhlnocerotidae#. Suidae#, Tragulidae#. Pecore# 25

Earth increased at this time, causing a worldwide change in the degree of seasonality which had tremendous repercussions upon global climates, vegetation belts and zoogeographic realms. Climatic changes have often been invoked to explain faunal turnover pulses (Vrba, 1985; Alroy, 1992). However, what causes the climate to change

in the first place has seldom been evinced. In searching the literature for ideas concerning global change we have come across data which throws much light on the possible causes of both climatic change and faunal turnover pulses. Comparison of the tectogenetic history of the Alpine fold belt (Scherba, 1987) and our faunal data reveals a

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994) 297-322

320

N°

i(] 0

0

1 2345678910110!

of

Genera 2345670

=-I 2 34567891011

z////////////////////A

t

2

~//////////////////////////A

3

r¢~//////////./~.

4

5

~//////////'////A

6

7 8

"/////////////////////~

"/////////~'//~//~/////////.////./~.

9 10 It

"//////A

"//////#,

~//////////////A

t2

~//////////~,

t3 14 15

46 17

r/J///////////~/A

t8 t9

~///////f///////////~,


~///////////////////#,

W~/////////////////////J

20 2t 22 25 24 25 Ma

LARGE MAMMAL GENERA IMMIGRANT TO AMERICA FROM OLD WORLD

LARGE MAMMAL GENERA IMMIGRANT TO SPAIN FROM NEW WORLD, ASIA AND AFRICA

LARGE MAMMAL GENERA IMMIGRANT TO E. AFRICA FROM EURASIA AND NEW WORLD

TECTOGENIC PHASES

Fig. 9. Correlation of intercontinental large mammal interchanges during the Neogene of North America, Spain and East Africa, and of tectogenic history of the Alpine Fold Belt.

M. Pickford, J. Morales/Palaeogeography, Palaeoclimatology, Palaeoecology 112 (1994) 297-322

remarkably close chronological correspondence between them (Fig. 9). Scherba's synthesis built on the work of Stille (1924) and others who recognised that tectogenesis occurred in pulses or "phases" rather than continuously. During the Tertiary and Quaternary there have been at least 9 tectogenic phases (Laramide I, Laramide II, Illyrian, Pyrenean, Savic, Styrian, Attic, Rhodanian and Valachian). The Laramide I tectogenic phase correlates in time with the K/T boundary, which was a period of major faunal change. The Pyrenean tectogenic phase correlates with the "grande coupure" of Europe and North America, which was also a period of profound faunal changes. The four faunal turnover pulses of the Neogene of Spain and East A~rica reported here correlate from oldest to youngest with the Styrian, Attic, Rhodanian and Valachian tectogenic phases. Considering the different histories of studies and the various dating methods employed, we consider that the chronology and the number of concordances between tectogenesis and faunal changes are remarkable. So remarkable in fact, that we consider that they each represent appropriate responses (one in the lithosphere, the other in the biosphere) to the same overall prime mover. Pickford (in prep.) examines the question further, but suffice to say at this stage that we see a close correspondence between the evolution of the biosphere and its substrate the lithosphere.

Acknowledgements We are anxious to thank the Direcci6n General de Investigaci6n Cientifica y T6cnica for extending to MP funds for a sabbatical visit to the Museo Nacional de Ciencias Naturales, Madrid. This study is part of the research project PB 92-0066 DGICYT "Historia evolutiva de los ruminantes del Mioceno inferior y medio de Espafia".

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