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A new species of Mirovia (Coniferales, Miroviaceae) from the Lower Cretaceous of the Iberian Ranges (Spain)
Cretaceous Research (2002) 23, 761–773 doi:10.1006/cres.2002.1023
A new species of Mirovia (Coniferales, Miroviaceae) from the Lower Cretaceous of the Iberian Ranges (Spain) Bernard Gomez School of Earth Sciences, University of Leeds, Leeds LS2 9JT, UK; e-mail: [email protected] Revised manuscript accepted 13 July 2002
The Lower–Middle Albian coaly clay bed of the Escucha Formation, which is exposed at Rubielos de Mora (eastern Iberian Ranges, Spain), contains a diverse fossil plant assemblage. Among the taxa present in this layer, Mirovia gothanii Gomez sp. nov. differs from other species of the genus by its greater leaf length, margins typically overhanging the depressed stomatal groove, a single short, blunt, papilla borne by each subsidiary cell, non-stomatal cells inside the groove and margins, and a higher number of resin ducts in the mesophyll. Morphological study of the well-preserved cuticles demonstrates that the species also occurs in Lower Cretaceous coals of Santa Maria de Meia` (Pyrenees, Spain) where Gothan (1954) described it as Sciadopitytes sp. Both localities constitute the southernmost extent of the genus in Laurasia when the family was likely to have reached its climax in terms of abundance and diversity. 2003 Published by Elsevier Science Ltd. K W: conifers; Mirovia; Early Cretaceous; Iberian Ranges; Spain.
1. Introduction During the Early Cretaceous, all the modern conifer families were represented in addition to a few extinct families such as the Cheirolepidiaceae and the Miroviaceae. Living conifer leaves are typically in the form of needles or scales with one to two veins, although in some genera the leaves are wide and contain many vascular bundles (e.g., Agathis). Harris (1969, 1979) classified Mesozoic conifer leaves in a system comprising eight form genera but further research, especially on specimens with preserved cuticle, has revealed a higher diversity of taxa (e.g., see Watson, 1988; Watson & Alvin, 2000). Aciculate fossil leaves displaying a median, abaxial stomatal zone or groove have for a long time been considered to be coniferalian, this character being unique in modern needle-bearing conifers to Sciadopitys verticillata (Thunberg) Siebold & Zuccarini (Manum et al., 2000). To name fossil Sciadopitys-like leaves, Halle (1915), Florin (1922) and subsequent authors used Sciadopitytes Goeppert & Menge. This genus was, however, initially employed for leaves preserved in amber on the Samland Peninsula (Baltic Sea, along the coast of East Prussia, Russia) and subsequently identified as members of the Ericaceae (Schimper & Schenk, 1890, pp. 346, 827). More recently Sciadopityoides Sveshnikova (1981) was 0195–6671/03/$30.00/0
substituted for Sciadopitytes Goeppert & Menge. Bose & Manum (1990) divided Sciadopityoides into four genera based on leaf and axis morphologies, leaf stomatal distribution and other epidermal characters of Barremian–Aptian specimens from Spitzbergen, Greenland and Baffin Island: Holkopitys Bose & Manum (monospecific), Mirovia Reymano´wna emend. Bose & Manum (eight species), Oswaldheeria Bose & Manum (four species) and Sciadopityoides Sveshnikova emend. Bose & Manum (eight species). Additionally Bose & Manum (1991) attributed a fifth genus, Tritaenia Maegdefrau & Rudolf (three species) to the extinct Miroviaceae Bose & Manum (1990, p. 64). All of these taxa have in common the abaxial, median stomatal zone, but this is set in a well-developed groove in Holkopitys, Mirovia and Sciadopityoides, whereas is not protected in a groove in Oswaldheeria and Tritaenia. The taxonomy and systematics of these genera and family have been recently discussed (Watson & Harrison, 1998; Manum et al., 2000; Watson et al., 2001).
2. Material The well-preserved leaf cuticles described in this paper were collected from a coaly clay layer within the Escucha Formation at the locality of El Paso, 2003 Published by Elsevier Science Ltd.
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B. Gomez
A new species of Mirovia from Spain
near Rubielos de Mora (eastern Iberian Ranges, Spain). Gomez et al. (1999, 2000, 2002) have systematically described the vegetative remains of Ginkgoales (Nehvizdya penalveri) and Cheirolepidiaceae (Frenelopsis turolensis), and associated fertile microsporangiate cones (Classostrobus turolensis), and the geological and palaeoenvironmental framework of this Early–Mid Albian assemblage.
3. Local palaeoenvironment Sedimentological and taphonomic analyses have shown that these species grew in a brackish coastal floodplain of the huge Escucha Delta described by Querol et al. (1992). Leaf-beds probably accumulated in deltaic coastal marshes, which are low energy environments receiving a large amount of sediment. Their development involved a massive supply of entire leaf litter from the land around the marshes via high-energy fluvial transport during short, flooding events (Gomez et al., 2000). The presence of mixed marine and freshwater algae, i.e. dinocysts and zygnematalean spores, respectively, confirms that these swamps received both marine and freshwater input. The xeromorphism of some taxa (e.g., F. turolensis) is interpreted to have developed in response to water-stress associated with the seasonally arid climate proposed by Ziegler et al. (1987).
4. Systematic palaeontology Order: Coniferales Family: Miroviaceae Bose & Manum, 1990, p. 64. Genus Mirovia Reymano´wna emend. Bose & Manum, 1990, p. 64. Type species. Mirovia szaferi Reymano´wna, 1985, p. 6. Original diagnosis. See Bose & Manum (1990, p. 64).
763
Emended diagnosis. Leaves linear, helically arranged and horizontally spreading; base tapering or decurrent; apex obtuse, acute or apiculate. Adaxial surface with or without a median furrow; abaxial surface with a distinct median stomatal groove. Resin ducts present. Cells of upper cuticle arranged in longitudinal rows, rectangular, trapezoidal or polygonal; anticlinal walls straight or slightly wavy, surface nonpapillate. Abaxial surface cells outside median groove like those of adaxial cuticle. Cells within median groove irregularly arranged, polygonal, shorter than cells outside groove; anticlinal walls straight; surface with or without papillae. Cells along margins of median groove mostly papillate; papillae varying in shape and size, surface non-tuberculate; margins of groove projecting over stomatal area but sometimes only weakly developed. Stomata confined to lower median groove, irregularly distributed or arranged in files, longitudinally or obliquely orientated, rarely transverse. Subsidiary cells 4–8, papillate or nonpapillate. Guard cells sunken, thinly cutinized. Remarks. The generic diagnosis provided by Bose & Manum (1990, p. 64) is slightly modified above to take into consideration the occurrence of: (1) more than 2–3 resin ducts; (2) slightly wavy anticlinal walls of some epidermal cells outside the stomatal groove; (3) sporadic development of weakly projecting stomatal groove margins; and (4) a wider range of subsidiary cell numbers. These refinements are derived from illustrations of the Mirovia species provided by Bose & Manum and from the features of the new species described here. Bose & Manum expressed doubts about some of the specimens included in M. szaferi by Reymano´wna (1985), because of the absence of projecting margins over the stomatal groove, but this concern seems unfounded. Notably, Bose & Manum (1990) included M. sibirica (Samylina) in the genus although this species does not possess projecting margins (Manum, 1987, table 2). Thus, it appears that the development of projecting stomatal groove margins is variably expressed in Mirovia.
Figure 1. Mirovia gothanii sp. nov., Lower–Middle Albian, Rubielos de Mora, Spain. A, holotype, emarginate to mucronate apices, MPZ 00/566; 4. B, bases with a proximal constriction and a decurrent insertion, MPZ 00/567; 4. C, adaxial cuticle devoid of stomatal apparatus and with rectangular epidermal cells in rows, MPZ 00/568; 75. D, abaxial cuticle comporting a median stomatal groove bounded by lateral areas without stomata; the groove margins are projecting and overhang the stomatal area, MPZ 00/568; 35. E, ordinary epidermal cells of the adaxial cuticle with wavy anticlinal walls, MPZ 00/568;280. F, set of stomata showing longitudinal or oblique orientations, MPZ 00/568; 330. G, distal termination of the stomatal groove as a tip before the margin; the stomatal groove displays numerous papillae, MPZ 00/568; 120. H, short conical papillae with generally rounded tops and stomata with papillate subsidiary cells, MPZ 00/568; 230.
764
B. Gomez
A new species of Mirovia from Spain
Mirovia gothanii sp. nov. Figures 1–3 1954 Sciadopitytes sp. (? n. sp.), Gothan, p. 337, figs 1–6. 1999 Pseudocycas sp., Gomez, Barale, Martı´n-Closas, The´venard & Philippe, p. 661, fig. 17. Derivation of name. From Dr Walther Gothan who first described Sciadopitys-like needles that are abundant in coals at Santa Maria de Meı´a (Lleida province, Pyrenees, Spain). Holotype. Museo Paleontolo´gico de Zaragoza, Zaragoza, Spain, catalogue no MPZ00/566, Escucha Formation, Rubielos de Mora locality, Teruel province (Gomez et al., 2002, text-fig. 2). Paratypes. Light microscope slide nos. MPZ00/560– 565, MPZ00/567–568 and SEM stub no. MPZ00/ 570. Other material. Light microscope slide MPZ00/569 and SEM stub MPZ00/571. Unnumbered material includes a large number of bases, middle parts and apices of leaves of variable length. Transversly broken leaves are found dispersed in the clay layer of the exposure of the Escucha Formation at Rubielos de Mora. Stratigraphic range. Lower–Middle Albian. Diagnosis. Linear leaf, up to at least 50 mm long, 1.3–2.2 mm wide, tapering imperceptibly into a proximal constriction just distal to abruptly swollen and decurrent base. Apiculate to mucronate apex, commonly missing. Stomatal groove depressed with overhanging margins, up to 120 m (average 50 m), never exceeding one-fifth of the groove width; in some cases there are regions along this groove where there are no overhanging margins. Groove in a point just below the apex. Cuticles 10–20 m thick. Stomatal density within the groove 140–170 per mm2. Stomatal orientation preferentially longitudinal. Stoma typically 70–110 m long and 60–90 m wide. Stoma with 4–7 subsidiary cells, one always in each polar position.
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Subsidiary cells, non-stomatal cells inside the groove and margins each bearing one single short blunt papilla. Mesophyll with 3–7 resin ducts. Description. The leaves are linear or slightly curved and have parallel margins. They are 1.3–2.2 mm wide and probably exceed 50 mm in length (Figure 1A, B). The basal insertion is represented by a triangular to rhomboidal cushion 1.3–1.9 mm wide (Figure 1B). One of the edges is longer and may correspond to the lowermost decurrent part on the axis. Just above the insertion area the leaves are swollen, then suddenly become narrow (0.8–1.5 mm wide) to form a very distinct constriction before widening gradually until they reach their maximum width. The obtuse or slightly acute apex is usually mucronate but the mucron is commonly missing (Figure 1A). The cuticles are 10–20 m thick, the adaxial and abaxial sides being almost the same thickness. Only the abaxial side displays a median stomatal groove, which occupies 1/5–1/4 of the 0.3–0.5 mm leaf width (Figure 1F) and ends in a point just below the apex (Figure 1G). The margins of both sides overhang the stomatal groove, extending up to 120 m (average 50 m) beyond the stomatal groove (Figures 1D, 3F). The stomata are scattered or tend to form discontinuous rows at the bottom of the stomatal groove (Figures 1D, 2D, H). The stomatal density within the groove ranges from 140 to 170 per mm2. The stomata are preferentially orientated longitudinally and only in rare cases obliquely (Figures 1F, 2H). The haplocheilic stomata are monocyclic with 4–(5–6)–7 subsidiary cells (Figure 3B, D), each subsidiary cell bearing one papilla (Figure 3A). There is always one subsidiary cell in each polar position. The stomata are slightly oval and measure 70–110 m long and 60– 90 m wide. The subsidiary cells measure 10–65 m (average 25 m) long and 9–18 m (average 13 m) wide, and are separated by anticlinal walls 1–2 m thick. The non-stomatal cells in the stomatal groove are small and rectangular to polygonal (Figure 2H). They are 17–35 m (average 24 m) long and 4–20 m (average 11 m) wide. Their anticlinal walls are 2–6 m thick. The ordinary epidermal cells of the abaxial side, outside the stomatal groove, are arranged
Figure 2. Mirovia gothanii sp. nov., Lower–Middle Albian, Rubielos de Mora, Spain. A, external view of the adaxial cuticle, MPZ 00/570;80. B, internal view of the adaxial cuticle, MPZ 00/570;40. C, external view of the abaxial cuticle showing the median stomatal groove, MPZ 00/570;40. D, internal view of the abaxial cuticle showing the median stomatal groove, MPZ 00/570;40. E, external view of the stomatal groove and the numerous short papillae that fill it, MPZ 00/571;270. F, internal view of the adaxial cuticle with hair bases and wavy anticlinal walls, MPZ 00/571;150. G, internal view of the abaxial cuticle showing the epidermal cells of the lateral non-stomatal areas arranged in rows with wavy anticlinal walls, MPZ 00/570;150. H, stomatal strip with longitudinally or obliquely orientated stomata, MPZ 00/570;150.
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A new species of Mirovia from Spain
in serial longitudinal rows (Figures 1D, E, 2G). They are rectangular to trapezoid in shape, 45–160 m (average 92 m) long and 9–35 m (average 22 m) wide. They show slightly wavy anticlinal walls 2–8 m thick. The ordinary epidermal cells of the projecting margins, the slopes and the bottom of the stomatal groove bear short, rounded to conical papillae with blunt tops (Figures 1G, H, 2C, E, 3C, E, F). These papillae measure 13–23 m (average 18 m) long and 9–20 m (average 16 m) wide at the base. The adaxial side shows a median wrinkle (Figure 2A). This side is completely devoid of stoma (Figures 1C, 2A, B). The epidermal cells are arranged in longitudinal rows and tend to converge when the width diminishes towards the apex. The cells are square, rectangular, trapezoidal or polygonal (Figure 2B, F), 25–105 m (average 50 m) long and 10– 50 m (average 25 m) wide. They display slightly wavy anticlinal walls 2–8 m thick. Inside the mesophyll 3–7 (average 5.5) resin ducts run along the length of the lamina (Figure 3G, H). Comparisons. Mirovia gothanii differs from Sciadopityoides Sveshnikova emend. Bose & Manum (1990, p. 21) in the shape of the basal lamina just above the point of attachment: M. gothanii has a slight constriction but Sciadopityoides has parallel margins and no constrictions (Table 1). Unlike M. gothanii, the monospecific genus Holkopitys Bose & Manum (1990, p. 49) displays two stomatal strips protected in a single groove with prominent margins where cells in each strip lack papillae (Table 1). In contrast to M. gothanii, the stomatal groove in Oswaldheeria Bose & Manum (1990, p. 39) is not depressed (Table 1). The closest resemblance exists between the new Spanish material and members of Mirovia Reymano´wna emend. Bose & Manum (1990, p. 64). However, six out of eight Mirovia species have leaf lengths of less than 15 mm (Table 1). The two other species are distinguishable from M. gothanii by: (1) the presence of longer ‘finger-like’ papillae on the projecting margins in Mirovia persulcata (Johansson) Bose & Manum, and (2) the absence of a projecting or papillate groove (see Manum, 1987, table 2 and Bose
767
& Manum, 1991, table 1 respectively) in Mirovia sibirica (Samylina) Bose & Manum. According to the illustrations in Gothan (1954), Sciadopitytes sp. from the Lower Cretaceous of Santa Maria de Meia` are in accordance with the specimens described here in many features: (1) width of the leaves (1.7–2.2 mm); (2) width of the stomatal groove (0.4–0.5 mm; Gothan, 1954, figs 1–2); (3) occurrence of an obtuse, emarginate apex (top of fig. 2 in Gothan, 1954) or with its mucron preserved (on the right of fig. 1 in Gothan, 1954); (4) stomatal groove weakly covered by margins (up to 70 m); (5) stomatal density about 150 stomata per mm2; (6) high density of papillae (fig. 4 in Gothan, 1954); and (7) short papillae (1.5–3.5 m long) rounded at their top (fig. 5 in Gothan, 1954). This new assignation of Gothan’s (1954) specimens was also proposed by Manum et al. (2000) who suggested close affinities with M. persulcata. Remarks. The linear leaves of Mirovia gothanii share several characters with the modern Sciadopitys verticillata: (1) the stomatal area is restricted to a more or less protected groove, and (2) each non-stomatal cell and each subsidiary cell of the stomatal strip bears one papilla, and these papillae protect the stomata (Halle, 1915, p. 511; Reymano´wna, 1985, p. 8). The leaves of Sciadopitys verticillata are, however, of two types: (1) brown, scale-like leaves spirally-arranged along the axis or disposed in very tight false whorls in the distal part, and (2) linear leaves with a single stomatal groove borne by small dwarf twigs. These ‘symphyllodes’ would have originated from the fusion of two leaves, the groove corresponding to the junction of their lower sides (Meyen, 1987, p. 212). Bose & Manum (1990, p. 17) found no evidence in the morphology of Mirovia leaves or shoots that favour such a phenomenon. In contrast to Sciadopitys verticillata, the leaves of M. gothanii are not dimorphic in venation or in stomatal distribution. None of the miroviaceous species possesses the leaves borne by small dwarf twigs or the pseudo-whorled leaf arrangement present in Sciadopitys verticillata (Bose & Manum, 1990, p. 14; Taylor & Taylor, 1993, p. 712), but evidence from denuded stems, leafy twigs, and the character of the
Figure 3. Mirovia gothanii sp. nov., Lower–Middle Albian, Rubielos de Mora, Spain. A, stoma in external view showing short papillae around the mouth of the stomatal pit, MPZ 00/571;600. B, stomatal apparatus with seven subsidiary cells, MPZ 00/570;600. C, inside of the stomatal groove in external view with papillae, MPZ 00/571;320. D, two stomata in external view showing four and six subsidiary cells respectively around the guard cells, MPZ 00/570;600. E, projecting and overhanging stomatal groove margin with papillae, MPZ 00/571;320. F, non-projecting and non-overhanging stomatal groove margin with papillae, MPZ 00/571;750. G, resin canals in the leaf mesophyll, MPZ 00/569;60. H, SEM of a resin canal, MPZ 00/571;320.
768
Table 1. Comparison of the species belonging to the family Miroviaceae (modified from Bose & Manum, 1990, 1991 and Manum et al., 1991)
Characters/Taxa
Mirovia florinii Bose & Manum
Mirovia groenlandica Bose & Manum
Mirovia ineffecta Bose & Manum
Mirovia lagerheimii (Johansson) Bose & Manum
Mirovia persulcata (Johansson) Bose & Manum
Mirovia sibirica (Samylina) Bose & Manum
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
?
?
8–15 + +
7–15 + + +
L 7–10 + +
10–12 + + +
10–15 +
50+ ? + +
40+ ? +
+ +
+ + +
+ + +
+ ?
(+) +
(+)
+ + (+)
+ + + (+)
+ + +
Location
Spitsbergen
Spitsbergen, Baffin Island
West Greenland
Spitsbergen, Baffin Island
northern Norway
northern Norway
Siberia
Age
Barremian–Aptian
Barremian–Aptian
Barremian–Aptian
Barremian–Aptian
Bajocian–Bathonian
Bajocian–Bathonian
Early Cretaceous
References
Bose & Manum (1990)
Bose & Manum (1990)
Bose & Manum (1991)
Bose & Manum (1990)
Johansson (1920); Florin (1922); Sveshnikova (1981); Manum (1987); Bose & Manum (1990)
Johansson (1920); Florin (1922); Sveshnikova (1981); Manum (1987); Bose & Manum (1990)
Samylina (1963); Sveshnikova (1981); Manum (1987); Bose & Manum (1990)
B. Gomez
Decurrent leaf base Hole in bottom of leaf Stomatal zone in groove Stomatal zone not in groove Stomata irregularly arranged Stomata in files or bands Furrow in upper surface Leaf dimorphism documented Stems, denuded (D) or leafy (L) Length of leaf (mm) Resin ducts Groove margin papillate Stomata orientated longitudinally Stomata orientated transversely Stomata orientated obliquely Stomata randomly arranged Subsidiary cells papillate Margins projecting over stomatal groove Papillae towards groove longer Non-stomatal cells inside groove with papillae
Mirovia capbohemanensis Bose & Manum
Table 1. Continued
Characters/taxa
Mirovia szaferi (Reymano´wna) Bose & Manum =type species
Mirovia gothanii sp. nov.
+
+
+
+ +
Oswaldheeria macrophylla (Florin) Bose & Manum
Oswaldheeria scotica (Florin) Bose & Manum
Holkopitys hoegii Bose & Manum
+
+
+
+
+
+ +
+ + (+) + + D 10–20 + +
+ + (+) +
+ +
+
50 + +
90 + +
15–20 ? +
+ +
+ +
+
+ +
+
+ +
10–14 + ? +
50+ + + +
8–15(22) + +
(+)
(+)
+ + +
+
+ ?
Location
Poland
Spain
Baffin Island, Spitsbergen
West Greenland, Baffin Island, Spitsbergen
northern Norway
Scotland
Baffin Island, Spitsbergen
Age
Early Bathonian
Albian
Barremian–Aptian
Barremian–Aptian
Bajocian–Bathonian
Late Jurassic
Barremian–Aptian
References
Reymano´wna (1985); Bose & Manum (1990)
herein
Bose & Manum (1990)
Florin (1922); Bose & Manum (1990)
Florin (1922); Sveshnikova (1981); Manum (1987); Bose & Manum (1990)
Florin (1922); Bose & Manum (1990)
Bose & Manum (1990)
A new species of Mirovia from Spain
Decurrent leaf base Hole in bottom of leaf Stomatal zone in groove Stomatal zone not in groove Stomata irregularly arranged Stomata in files or bands Furrow in upper surface Leaf dimorphism documented Stems, denuded (D) or leafy (L) Length of leaf (mm) Resin ducts Groove margin papillate Stomata orientated longitudinally Stomata orientated transversely Stomata orientated obliquely Stomata randomly arranged Subsidiary cells papillate Margins projecting over stomatal groove Papillae towards groove longer Non-stomatal cells inside groove with papillae
Oswaldheeria arctica Bose & Manum
Oswaldheeria hallei (Florin) Bose & Manum
769
770
Table 1. Continued
Characters/taxa
+ +
Sciadopityoides greenboana Watson et al.
Sciadopityoides ikorfatensis Bose & Manum
Sciadopityoides microphylla (Heer) Bose & Manum
Sciadopityoides nathorstii (Halle) Sveshnikova
Sciadopityoides ukrainensis Doludenko & Sveshnikova
Sciadopityoides uralensis (Dorofeev & Sveshnikova) Sveshnikova
Sciadopityoides variabilis (Bose) Sveshnikova
+ (+) +
+ +
+ +
+ +
+ +
+ +
+ +
+
+
+
+
+
+ + L 13–18
+
?
?
+ (+)
+ + + D 7–18 + +
+ ?
9 + +
+ +
+ +
10–14(20) +
D 40–50 + + +
(6)12–15(24)
+ +
+
(+)
(+)
+
+
+
(+) +
?
+
+ +
+
+
+
Location
West Greenland
England
West Greenland
Baffin Island, Spitsbergen, West Greenland
West Greenland
Western Ukraine
Urals
Baffin Island
Age
Barremian–Aptian
Berriasian– Hauterivian
Barremian–Aptian
Barremian–Aptian
Barremian–Aptian
Late Jurassic
Cenomanian– Turonian
Barremian–Aptian
References
Heer (1868, 1876); Halle (1915); Sveshnikova (1981)
Watson et al. (2001)
Bose & Manum (1990)
Heer (1876); Bose & Manum (1990)
Halle (1915); Sveshnikova (1981)
Doludenko (1963); Sveshnikova (1981); Manum (1987)
Dorofeev & Sveshnikova (1959); Doludenko (1963); Sveshnikova (1981); Manum (1987)
Bose (1955); Sveshnikova (1981)
B. Gomez
Decurrent leaf base Hole in bottom of leaf Stomatal zone in groove Stomatal zone not in groove Stomata irregularly arranged Stomata in files or bands Furrow in upper surface Leaf dimorphism documented Stems, denuded (D) or leafy (L) Length of leaf (mm) Resin ducts Groove margin papillate Stomata orientated longitudinally Stomata orientated transversely Stomata orientated obliquely Stomata randomly arranged Subsidiary cells papillate Margins projecting over stomatal groove Papillae towards groove longer Non-stomatal cells inside groove with papillae
Sciadopityoides crameri (Heer) Sveshnikova
A new species of Mirovia from Spain
leaf bases in detached leaves show that the leaves were spirally attached or horizontally spreading (e.g., Bose & Manum, 1991, p. 19). There is no evidence to suggest that small leaves (scale leaves) subtended large leaves (needles) as in the extant species. Moreover, the stomata of Sciadopitys verticillata adult leaves do not have the same structure (Watson & Harrison, 1998, fig. 16C) as those of the Miroviaceae and, in particular, show 8–13 (14) subsidiary cells (Florin, 1931; Lemoine-Se´bastian, 1972) in contrast, for example, to Mirovia gothanii which only displays 4–7 subsidiary cells. In accordance with the hypothesis of Bose & Manum (1990, p. 17) concerning Mirovia and Oswaldheeria, the decurrent tapered base and the leaf cushion of Mirovia gothanii suggest that the leaves of the latter could have been arranged horizontally. However it is difficult to ascertain whether they were deciduous like many other Mesozoic ‘Sciadopitys-like’ taxa mentioned above (Manum et al., 2000) or persistent, being only separated after the death of the shoot as observed in Taxus baccata L. (pers. obs.). The exact evolutionary relationships between extinct and extant gymnosperm families remain controversial and one may question whether the Miroviaceae are sufficiently distinct to be recognized as a separate family (Watson et al., 2001). Among the living conifers the closest affinities of the Miroviaceae are undoubtedly somewhere within the Cupressaceae sensu stricto, Sciadopityaceae or Taxodiaceae, which depending on systematic treatments, are considered to be three distinct families (Price, 1989; Page, 1990; Ohsawa, 1994), or two, with the Sciadopityaceae included as a subgroup of the Taxodiaceae (Hart, 1987; Stewart & Rothwell, 1993; Taylor & Taylor, 1993; Yao et al., 1997) or with the Taxodiaceae completely merged into the Cupressaceae sensu lato (Eckenwalder, 1976; Brunsfeld et al., 1994, Gadek et al., 2000). So, in the current state of the art, the assignation of ‘Sciadopitys-like’ fossil leaves to one or other of the extant families may introduce more confusion than clarity. Otherwise, the fossil record of conifers suggests that the Taxodiaceae originated during the Triassic and was well established by the Jurassic (Lemoigne, 1967; Miller, 1982; Yao et al., 1997), and that the Cupressaceae may have had its origin in this family (Alvin et al., 1982). Oxfordian taxodiaceous woods, along with known reproductive structures (Yao et al., 1997, 1998), reinforce the view that this family was well separated from Cupressaceae by the Middle Jurassic (Philippe, 1994). Whatever the phyletic history was, a few living cupressaceous and taxodiaceous taxa display acicular/linear leaves. Acicular leaves of Juniperus L. (Cupressaceae sensu
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stricto) bear one (e.g., J. conferta Parl or rigida Sieb. & Zucc.) or two (e.g. J. communis L., drupacea Labille or oxycedrus L.) stomatal bands, but the stomata are never set in a groove as in Holkopitys, Mirovia and Sciadopityoides. Juniperus leaves generally remain attached to the stem even long after their death. In addition, living relatives of Juniperus (e.g., J. communis or oxycedrus) usually have strongly keeled leaves with well-developed sclerenchyma joining the adaxial and abaxial surface, which would probably be preserved during fossil diagenesis, but they have never been observed in the Miroviaceae. Within the Taxodiaceae, Athrotaxis selaginoides D. Don, Cunninghamia (Richard) Brown, Glyptostrobus Endlicher, Metasequoia Miki, Sequoia Endlicher, and Taxodium Richard have linear or lanceolate leaves. Taxodiaceae usually show amphistomatic leaves, except for Metasequoia glyptostroboides Hu & Cheng, with stomata arranged in bands or more exceptionally scattered in Athrotaxis cupressoides D. Don, Glyptostrobus lineatus (Poir.) Druce, and Sequoiadendron giganteum (Lindley) Buchholtz (Srinivasan & Friis, 1989). However, none of these has the typical single stomatal groove of the Miroviaceae and, thus, I am inclined here to prefer the genus Mirovia and the family Miroviaceae in the sense of Manum et al. (2000) rather than the Sciadopityoides form-genus concept of Watson et al. (2001). The Miroviaceae constituted a significant group in Early Cretaceous Arctic floras when the family reached its climax in terms of abundance and diversity (Manum, 1987, p. 21). Some sporadic occurrences extending into Eurasia are known from the mid-Jurassic–Late Cretaceous (Bose & Manum, 1990). Other data from the English Wealden have demonstrated the occurrence of the Miroviaceae in Western Europe: Sciadopitytes sp. nov. (31TaxodSc; Oldham, 1976, p. 462, pl. 73, figs 1–6) and Sciadopityoides greenboana Watson et al. (2001). Data from Rubielos de Mora now establish that its geographical expansion reached southern parts of the Northern Hemisphere (approximately the Albian 30N according to Smith et al., 1994), even below the present 40N postulated by Florin (1963) and Sveshnikova (1981). At Rubielos de Mora, as well as at Santa Maria de Meia`, Mirovia gothanii constituted a dominant component of the flora. There are likely to be palaeoecological and palaeoenvironmental explanations for the success of the family during the Early Cretaceous. Strong xeromorphic adaptations are expressed in the absence of stomata on the adaxial side while, on the abaxial cuticle, they are arranged close to each other in a single strip sunken into a groove with a protruding margin, and are protected by papillae. In Spain the success of M. gothanii may
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have been related to a unique set of climatic and edaphic conditions (Gomez et al., 1999, p. 673). On the other hand, as noted by Manum et al. (2000, pp. 226, 227), the apparent paradox of xeromorphic adaptations of the Miroviaceae in non-xeric habitats from Spain to the Arctic during the Jurassic– Cretaceous period can be interpreted as ‘a phylogenetically conservative feature of gymnosperms in general or more specifically as a functional adaptation to less efficient water conductive system’. Acknowledgements This research was supported by a European Community Marie Curie Fellowship (HPMF-CT-200201584), by UMR 5125 and the ECLIPSE programme of the French CNRS, and by Spanish Government projects BTE2001-0185-C02-01 and B052001-0173. I thank the referees and editor for their comments on the original manuscript. References Alvin, K. L., Dalby, D. H. & Oladele, F. A. 1982. Numerical analysis of cuticular characters in Cupressaceae. In The plant cuticle (eds Cutler, D. F., Alvin, K. L. & Price, C. E.), pp. 379– 396 (Academic Press, London). Bose, M. N. 1955. Sciadopitytes variabilis n. sp. from the Arctic of Canada. Norsk Geologisk Tidskrift 35, 53–68. Bose, M. N. & Manum, S. B. 1990. Mesozoic conifer leaves with ‘Sciadopitys-like’ stomatal distribution. A re-evaluation based on fossils from Spitsbergen, Greenland and Baffin Island. Norsk Polarinstitutt Skrifter 192, 1–81. Bose, M. N. & Manum, S. B. 1991. Additions to the family Miroviaceae (Coniferae) from the Lower Cretaceous of West Greenland and Germany: Mirovia groenlandica n. sp., Tritaenia crassa (Seward) comb. nov., and Tritaenia linkii Ma¨gdefrau et Rudolph emend. Polar Research 9, 9–20. Brunsfeld, S. J., Soltis, P. S., Soltis, D. E., Gadek, P. A., Quinn, C. J., Strenge, D. D. & Ranker, T. A. 1994. Phylogenetic relationships among the genera of Taxodaceae and Cupressaceae: evidence from rbcL sequences. Systematic Botany 19, 253–262. Doludenko, M. P. 1963. A new species of Sciadopitys from the Jurassic of western Ukraine. Paleontological Zhurnal 1963 (1), 123–126. [In Russian] Dorofeev, P. I. & Sveshnikova, I. N. 1959. On a find of remains of the genus Sciadopitys S. et Z. in Upper Cretaceous deposits of the Urals. Doklady Akademiya Nauk SSSR 128, 1276–1278. [In Russian] Eckenwalder, J. E. 1976. Re-evaluation of Cupressaceae and Taxodiaceae: a proposed merger. Madron˜o 23, 237–256. Florin, R. 1922. On the geological history of the Sciadopitineae. Svensk Botanisk Tidskrift 16, 260–270. Florin, R. 1931. Untersuchungen zur Stammesgeschichte der Coniferales und Cordaitales. Kungliga Svenska Vetenskapsakademiens Handlingar 3 10, 1–588. Florin, R. 1963. The distribution of conifer and taxad genera in time and space. Acta Horti Bergiani 20, 121–312. Gadek, P. A., Alpers, D. L., Heslewood, M. M. & Quinn, C. J. 2000. Relationships within Cupressaceae sensu lato: a combined morphological and molecular approach. American Journal of Botany 87, 1044–1057. Gomez, B., Barale, G., Martı´n-Closas, C., The´venard, F. & Philippe, M. 1999. De´couverte d’une flore a` Ginkgoales,
Bennettitales et Conife´rales dans le Cre´tace´ infe´rieur de la Formation Escucha (Chaıˆne Ibe´rique Orientale, Teruel, Espagne). Neues Jahrbuch fu¨r Geologie und Pala¨ontologie, Monatshefte 11, 661–675. Gomez, B., Martı´n-Closas, C., Barale, G. & The´venard, F. 2000. A new species of Nehvizdya (Ginkgoales) from the Lower Cretaceous of the Iberian Ranges (Spain). Review of Palaeobotany and Palynology 111, 49–70. Gomez, B., Martı´n-Closas, C., Barale, G., Sole´ de Porta, N., The´venard, F. & Guignard, G. 2002. Frenelopsis (Coniferales: Cheirolepidiaceae) and related male organ genera from the Lower Cretaceous of Spain. Palaeontology 45, 997–1036. Gothan, W. 1954. U } ber ein Massenvorkommen von Sciadopitytes Nadeln in Kohligen Ablagerungen des Oberen Jura oder Wealden der Spanischen Ost-Pyrena¨en. Svensk Botanisk Tidskrift 48, 337– 342. Halle, T. G. 1915. Some xerophytic leaf-structures in Mesozoic plants. Geologiska Fo¨reningens i Stockholm Fo¨rhandlingar 37, 493– 520. Harris, T. M. 1969. Naming a fossil conifer. In J. Sen Memorial Volume, pp. 243–252 (J. Sen Memorial Committee and Botanical Society of Bengal, Calcutta). Harris, T. M. 1979. The Yorkshire Jurassic Flora, Volume 5. Coniferales, 166 pp. [British Museum (Natural History), London]. Hart, J. A. 1987. A cladistic analysis of conifers: preliminary results. Journal of the Arnold Arboretum 68, 269–307. Heer, O. 1868. Flora fossilis Arctica, I. Die fossile flora der Polarla¨nder, 192 pp. (Schulthess, Zu¨rich) Heer, O. 1876. Flora fossilis Arctica, IV, part 1. Beitra¨ge zur fossilen Flora Spitzbergens. Kungliga Svenska VetenskapsAkademiens Handlingar 14 (5), 1–144. Johansson, N. 1920. Neue mesozoische Pflanzen aus Ando¨ in Norwegen. Svensk Botanisk Tidskrift 14, 249–257. Lemoigne, Y. 1967. Pale´oflore a` Cupressales dans le Trias–Rhe´tien du Contentin. Comptes Rendus de l’Acade´mie des Sciences (Paris) 264, 715–718. Lemoine-Se´bastian, C. 1972. Structures e´pidermiques chez Sciadopitys et interpre´tation des organes. Bulletin de la Socie´te´ Botanique de France 119, 61–74. Manum, S. B. 1987. Mesozoic Sciadopitys-like leaves with observations on four species from Andøya, northern Norway (Jurassic) and emendation of Sciadopityoides Sveshnikova. Review of Palaeobotany and Palynology 51, 165–168. Manum, S. B., Bose, M. N. & Vigran, J. O. 1991. The Jurassic flora of Andøya, northern Norway. Review of Palaeobotany and Palynology 68, 233–256. Manum, S. B., van Konijnenburg-van Cittert, J. H. A. & Wilde, V. 2000. Tritaenia Maegefrau et Rudolf, Mesozoic ‘Sciadopityslike’ leaves in mass accumulations. Review of Palaeobotany and Palynology 109, 255–269. Meyen, S. V. 1987. Fundamentals of palaeobotany, 432 pp. (Chapman and Hall, London). Miller, C. N. 1982. Current status of Paleozoic and Mesozoic conifers. Review of Palaeobotany and Palynology 37, 99–114. Ohsawa, T. 1994. Anatomy and relationships of petrified seed cones of the Cupressaceae, Taxodiaceae and Sciadopityaceae. Journal of Plant Research 107, 503–512. Oldham, T. C. B. 1976. Flora of the Wealden plant debris beds of England. Palaeontology 19, 437–502. Page, C. N. 1990. Pinatae. In The families and genera of vascular plants, vol. I, Pteridophytes and gymnosperms (eds Kramer, K. U. & Green, P. S.), pp. 290–348 (Springer-Verlag, Berlin). Philippe, M. 1994. Radiation pre´coce des conifers Taxodiaceae et bois affines du Jurassique de France. Lethaia 27, 67–75. Price, R. A. 1989. An immunological comparison of the Sciadopityaceae, Taxodiaceae, and Cupressaceae. Systematic Botany 14, 141–149. Querol, X., Salas, R., Pardo, G. & Ardevol, L. 1992. Albian coal-bearing deposits of the Iberian Range in north-eastern Spain. Geological Society of America, Special Paper 267, 193–208.
A new species of Mirovia from Spain Reymano´wna, M. 1985. Mirovia szaferi gen. et sp. nov. (Ginkgoales) from the Jurassic of Krako´w region, Poland. Acta Palaeobotanica 25, 3–12. Samylina, I. N. 1963. The Mesozoic flora of the lower reaches of the Aldan river. Trudy Botanicheskiy Institut Akademiya Nauk SSSR, Serya 8, Paleobotanica 4, 205–229. [In Russian] Schimper, W. Ph. & Schenk, A. 1890. Zittel’s Handbuch der Palaeontologie II, 958 pp. (Abteilung Palaeophytologie Verlag von R. Oldenburg, Mu¨nchen/Leipzig) Smith, A. G., Smith, D. G. & Funnell, B. M. 1994. Atlas of Mesozoic and Cenozoic coastlines, 99 pp. (Cambridge University Press, Cambridge). Stewart, W. N. & Rothwell, G. W. 1993. Paleobotany and the evolution of plants, 521 pp. (Cambridge University Press, Cambridge). Sveshnikova, I. N. 1981. The new fossil genus Sciadopityoides (Pinopsida). Botanicheskiy Zhurnal 66, 1721–1729. [In Russian] Taylor, T. N. & Taylor, E. L. 1993. The biology and evolution of fossil plants, 982 pp. (Prentice Hall, Englewood Cliffs, NJ) Watson, J. 1988. The Cheirolepidiaceae. In Origin and evolution of gymnosperms (ed. Beck, C. B.), pp. 382–447 (Columbia University Press, New York).
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Watson, J. & Alvin, K. L. 2000. The cheirolepidiaceous conifers Frenelopsis occidentalis Heer and Watsoniocladus valdensis (Seward) in the Wealden of Germany. Cretaceous Research 20, 315–326. Watson, J. & Harrison, N. A. 1998. Abietites linkii (Ro¨mer) and Pseudotorellia heterophylla Watson: coniferous or ginkgoalean? Cretaceous Research 19, 239–278. Watson, J., Lydon, S. J. & Harrison, N. A. 2001. A revision of the English Wealden Flora, III: Czekanowskiales, Ginkgoales and allied Coniferales. Bulletin of the Natural History Museum, London (Geology) 57, 29–82. Yao, X., Taylor, T. N. & Taylor, E. L. 1997. A taxodiaceous seed cone from the Triassic of Antarctica. American Journal of Botany 84, 343–354. Yao, X., Zhou, Z. & Zhang, B. 1998. Reconstruction of the Jurassic conifer Sewardiodendron laxum (Taxodiaceae). American Journal of Botany 85, 1289–1300. Ziegler, A. M., Raymond, A. M., Gierlowski, T. C., Horrell, M. A., Rowley, D. B. & Lottes, A. L. 1987. Coal, climate and terrestrial productivity: the present and Early Cretaceous compared. In Coal and coal-bearing strata: recent advances (ed. Scott, A. C.), Geological Society, London, Special Publication 32, 25–49.
A new species of Mirovia (Coniferales, Miroviaceae) from the Lower Cretaceous of the Iberian Ranges (Spain) Bernard Gomez School of Earth Sciences, University of Leeds, Leeds LS2 9JT, UK; e-mail: [email protected] Revised manuscript accepted 13 July 2002
The Lower–Middle Albian coaly clay bed of the Escucha Formation, which is exposed at Rubielos de Mora (eastern Iberian Ranges, Spain), contains a diverse fossil plant assemblage. Among the taxa present in this layer, Mirovia gothanii Gomez sp. nov. differs from other species of the genus by its greater leaf length, margins typically overhanging the depressed stomatal groove, a single short, blunt, papilla borne by each subsidiary cell, non-stomatal cells inside the groove and margins, and a higher number of resin ducts in the mesophyll. Morphological study of the well-preserved cuticles demonstrates that the species also occurs in Lower Cretaceous coals of Santa Maria de Meia` (Pyrenees, Spain) where Gothan (1954) described it as Sciadopitytes sp. Both localities constitute the southernmost extent of the genus in Laurasia when the family was likely to have reached its climax in terms of abundance and diversity. 2003 Published by Elsevier Science Ltd. K W: conifers; Mirovia; Early Cretaceous; Iberian Ranges; Spain.
1. Introduction During the Early Cretaceous, all the modern conifer families were represented in addition to a few extinct families such as the Cheirolepidiaceae and the Miroviaceae. Living conifer leaves are typically in the form of needles or scales with one to two veins, although in some genera the leaves are wide and contain many vascular bundles (e.g., Agathis). Harris (1969, 1979) classified Mesozoic conifer leaves in a system comprising eight form genera but further research, especially on specimens with preserved cuticle, has revealed a higher diversity of taxa (e.g., see Watson, 1988; Watson & Alvin, 2000). Aciculate fossil leaves displaying a median, abaxial stomatal zone or groove have for a long time been considered to be coniferalian, this character being unique in modern needle-bearing conifers to Sciadopitys verticillata (Thunberg) Siebold & Zuccarini (Manum et al., 2000). To name fossil Sciadopitys-like leaves, Halle (1915), Florin (1922) and subsequent authors used Sciadopitytes Goeppert & Menge. This genus was, however, initially employed for leaves preserved in amber on the Samland Peninsula (Baltic Sea, along the coast of East Prussia, Russia) and subsequently identified as members of the Ericaceae (Schimper & Schenk, 1890, pp. 346, 827). More recently Sciadopityoides Sveshnikova (1981) was 0195–6671/03/$30.00/0
substituted for Sciadopitytes Goeppert & Menge. Bose & Manum (1990) divided Sciadopityoides into four genera based on leaf and axis morphologies, leaf stomatal distribution and other epidermal characters of Barremian–Aptian specimens from Spitzbergen, Greenland and Baffin Island: Holkopitys Bose & Manum (monospecific), Mirovia Reymano´wna emend. Bose & Manum (eight species), Oswaldheeria Bose & Manum (four species) and Sciadopityoides Sveshnikova emend. Bose & Manum (eight species). Additionally Bose & Manum (1991) attributed a fifth genus, Tritaenia Maegdefrau & Rudolf (three species) to the extinct Miroviaceae Bose & Manum (1990, p. 64). All of these taxa have in common the abaxial, median stomatal zone, but this is set in a well-developed groove in Holkopitys, Mirovia and Sciadopityoides, whereas is not protected in a groove in Oswaldheeria and Tritaenia. The taxonomy and systematics of these genera and family have been recently discussed (Watson & Harrison, 1998; Manum et al., 2000; Watson et al., 2001).
2. Material The well-preserved leaf cuticles described in this paper were collected from a coaly clay layer within the Escucha Formation at the locality of El Paso, 2003 Published by Elsevier Science Ltd.
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near Rubielos de Mora (eastern Iberian Ranges, Spain). Gomez et al. (1999, 2000, 2002) have systematically described the vegetative remains of Ginkgoales (Nehvizdya penalveri) and Cheirolepidiaceae (Frenelopsis turolensis), and associated fertile microsporangiate cones (Classostrobus turolensis), and the geological and palaeoenvironmental framework of this Early–Mid Albian assemblage.
3. Local palaeoenvironment Sedimentological and taphonomic analyses have shown that these species grew in a brackish coastal floodplain of the huge Escucha Delta described by Querol et al. (1992). Leaf-beds probably accumulated in deltaic coastal marshes, which are low energy environments receiving a large amount of sediment. Their development involved a massive supply of entire leaf litter from the land around the marshes via high-energy fluvial transport during short, flooding events (Gomez et al., 2000). The presence of mixed marine and freshwater algae, i.e. dinocysts and zygnematalean spores, respectively, confirms that these swamps received both marine and freshwater input. The xeromorphism of some taxa (e.g., F. turolensis) is interpreted to have developed in response to water-stress associated with the seasonally arid climate proposed by Ziegler et al. (1987).
4. Systematic palaeontology Order: Coniferales Family: Miroviaceae Bose & Manum, 1990, p. 64. Genus Mirovia Reymano´wna emend. Bose & Manum, 1990, p. 64. Type species. Mirovia szaferi Reymano´wna, 1985, p. 6. Original diagnosis. See Bose & Manum (1990, p. 64).
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Emended diagnosis. Leaves linear, helically arranged and horizontally spreading; base tapering or decurrent; apex obtuse, acute or apiculate. Adaxial surface with or without a median furrow; abaxial surface with a distinct median stomatal groove. Resin ducts present. Cells of upper cuticle arranged in longitudinal rows, rectangular, trapezoidal or polygonal; anticlinal walls straight or slightly wavy, surface nonpapillate. Abaxial surface cells outside median groove like those of adaxial cuticle. Cells within median groove irregularly arranged, polygonal, shorter than cells outside groove; anticlinal walls straight; surface with or without papillae. Cells along margins of median groove mostly papillate; papillae varying in shape and size, surface non-tuberculate; margins of groove projecting over stomatal area but sometimes only weakly developed. Stomata confined to lower median groove, irregularly distributed or arranged in files, longitudinally or obliquely orientated, rarely transverse. Subsidiary cells 4–8, papillate or nonpapillate. Guard cells sunken, thinly cutinized. Remarks. The generic diagnosis provided by Bose & Manum (1990, p. 64) is slightly modified above to take into consideration the occurrence of: (1) more than 2–3 resin ducts; (2) slightly wavy anticlinal walls of some epidermal cells outside the stomatal groove; (3) sporadic development of weakly projecting stomatal groove margins; and (4) a wider range of subsidiary cell numbers. These refinements are derived from illustrations of the Mirovia species provided by Bose & Manum and from the features of the new species described here. Bose & Manum expressed doubts about some of the specimens included in M. szaferi by Reymano´wna (1985), because of the absence of projecting margins over the stomatal groove, but this concern seems unfounded. Notably, Bose & Manum (1990) included M. sibirica (Samylina) in the genus although this species does not possess projecting margins (Manum, 1987, table 2). Thus, it appears that the development of projecting stomatal groove margins is variably expressed in Mirovia.
Figure 1. Mirovia gothanii sp. nov., Lower–Middle Albian, Rubielos de Mora, Spain. A, holotype, emarginate to mucronate apices, MPZ 00/566; 4. B, bases with a proximal constriction and a decurrent insertion, MPZ 00/567; 4. C, adaxial cuticle devoid of stomatal apparatus and with rectangular epidermal cells in rows, MPZ 00/568; 75. D, abaxial cuticle comporting a median stomatal groove bounded by lateral areas without stomata; the groove margins are projecting and overhang the stomatal area, MPZ 00/568; 35. E, ordinary epidermal cells of the adaxial cuticle with wavy anticlinal walls, MPZ 00/568;280. F, set of stomata showing longitudinal or oblique orientations, MPZ 00/568; 330. G, distal termination of the stomatal groove as a tip before the margin; the stomatal groove displays numerous papillae, MPZ 00/568; 120. H, short conical papillae with generally rounded tops and stomata with papillate subsidiary cells, MPZ 00/568; 230.
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Mirovia gothanii sp. nov. Figures 1–3 1954 Sciadopitytes sp. (? n. sp.), Gothan, p. 337, figs 1–6. 1999 Pseudocycas sp., Gomez, Barale, Martı´n-Closas, The´venard & Philippe, p. 661, fig. 17. Derivation of name. From Dr Walther Gothan who first described Sciadopitys-like needles that are abundant in coals at Santa Maria de Meı´a (Lleida province, Pyrenees, Spain). Holotype. Museo Paleontolo´gico de Zaragoza, Zaragoza, Spain, catalogue no MPZ00/566, Escucha Formation, Rubielos de Mora locality, Teruel province (Gomez et al., 2002, text-fig. 2). Paratypes. Light microscope slide nos. MPZ00/560– 565, MPZ00/567–568 and SEM stub no. MPZ00/ 570. Other material. Light microscope slide MPZ00/569 and SEM stub MPZ00/571. Unnumbered material includes a large number of bases, middle parts and apices of leaves of variable length. Transversly broken leaves are found dispersed in the clay layer of the exposure of the Escucha Formation at Rubielos de Mora. Stratigraphic range. Lower–Middle Albian. Diagnosis. Linear leaf, up to at least 50 mm long, 1.3–2.2 mm wide, tapering imperceptibly into a proximal constriction just distal to abruptly swollen and decurrent base. Apiculate to mucronate apex, commonly missing. Stomatal groove depressed with overhanging margins, up to 120 m (average 50 m), never exceeding one-fifth of the groove width; in some cases there are regions along this groove where there are no overhanging margins. Groove in a point just below the apex. Cuticles 10–20 m thick. Stomatal density within the groove 140–170 per mm2. Stomatal orientation preferentially longitudinal. Stoma typically 70–110 m long and 60–90 m wide. Stoma with 4–7 subsidiary cells, one always in each polar position.
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Subsidiary cells, non-stomatal cells inside the groove and margins each bearing one single short blunt papilla. Mesophyll with 3–7 resin ducts. Description. The leaves are linear or slightly curved and have parallel margins. They are 1.3–2.2 mm wide and probably exceed 50 mm in length (Figure 1A, B). The basal insertion is represented by a triangular to rhomboidal cushion 1.3–1.9 mm wide (Figure 1B). One of the edges is longer and may correspond to the lowermost decurrent part on the axis. Just above the insertion area the leaves are swollen, then suddenly become narrow (0.8–1.5 mm wide) to form a very distinct constriction before widening gradually until they reach their maximum width. The obtuse or slightly acute apex is usually mucronate but the mucron is commonly missing (Figure 1A). The cuticles are 10–20 m thick, the adaxial and abaxial sides being almost the same thickness. Only the abaxial side displays a median stomatal groove, which occupies 1/5–1/4 of the 0.3–0.5 mm leaf width (Figure 1F) and ends in a point just below the apex (Figure 1G). The margins of both sides overhang the stomatal groove, extending up to 120 m (average 50 m) beyond the stomatal groove (Figures 1D, 3F). The stomata are scattered or tend to form discontinuous rows at the bottom of the stomatal groove (Figures 1D, 2D, H). The stomatal density within the groove ranges from 140 to 170 per mm2. The stomata are preferentially orientated longitudinally and only in rare cases obliquely (Figures 1F, 2H). The haplocheilic stomata are monocyclic with 4–(5–6)–7 subsidiary cells (Figure 3B, D), each subsidiary cell bearing one papilla (Figure 3A). There is always one subsidiary cell in each polar position. The stomata are slightly oval and measure 70–110 m long and 60– 90 m wide. The subsidiary cells measure 10–65 m (average 25 m) long and 9–18 m (average 13 m) wide, and are separated by anticlinal walls 1–2 m thick. The non-stomatal cells in the stomatal groove are small and rectangular to polygonal (Figure 2H). They are 17–35 m (average 24 m) long and 4–20 m (average 11 m) wide. Their anticlinal walls are 2–6 m thick. The ordinary epidermal cells of the abaxial side, outside the stomatal groove, are arranged
Figure 2. Mirovia gothanii sp. nov., Lower–Middle Albian, Rubielos de Mora, Spain. A, external view of the adaxial cuticle, MPZ 00/570;80. B, internal view of the adaxial cuticle, MPZ 00/570;40. C, external view of the abaxial cuticle showing the median stomatal groove, MPZ 00/570;40. D, internal view of the abaxial cuticle showing the median stomatal groove, MPZ 00/570;40. E, external view of the stomatal groove and the numerous short papillae that fill it, MPZ 00/571;270. F, internal view of the adaxial cuticle with hair bases and wavy anticlinal walls, MPZ 00/571;150. G, internal view of the abaxial cuticle showing the epidermal cells of the lateral non-stomatal areas arranged in rows with wavy anticlinal walls, MPZ 00/570;150. H, stomatal strip with longitudinally or obliquely orientated stomata, MPZ 00/570;150.
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B. Gomez
A new species of Mirovia from Spain
in serial longitudinal rows (Figures 1D, E, 2G). They are rectangular to trapezoid in shape, 45–160 m (average 92 m) long and 9–35 m (average 22 m) wide. They show slightly wavy anticlinal walls 2–8 m thick. The ordinary epidermal cells of the projecting margins, the slopes and the bottom of the stomatal groove bear short, rounded to conical papillae with blunt tops (Figures 1G, H, 2C, E, 3C, E, F). These papillae measure 13–23 m (average 18 m) long and 9–20 m (average 16 m) wide at the base. The adaxial side shows a median wrinkle (Figure 2A). This side is completely devoid of stoma (Figures 1C, 2A, B). The epidermal cells are arranged in longitudinal rows and tend to converge when the width diminishes towards the apex. The cells are square, rectangular, trapezoidal or polygonal (Figure 2B, F), 25–105 m (average 50 m) long and 10– 50 m (average 25 m) wide. They display slightly wavy anticlinal walls 2–8 m thick. Inside the mesophyll 3–7 (average 5.5) resin ducts run along the length of the lamina (Figure 3G, H). Comparisons. Mirovia gothanii differs from Sciadopityoides Sveshnikova emend. Bose & Manum (1990, p. 21) in the shape of the basal lamina just above the point of attachment: M. gothanii has a slight constriction but Sciadopityoides has parallel margins and no constrictions (Table 1). Unlike M. gothanii, the monospecific genus Holkopitys Bose & Manum (1990, p. 49) displays two stomatal strips protected in a single groove with prominent margins where cells in each strip lack papillae (Table 1). In contrast to M. gothanii, the stomatal groove in Oswaldheeria Bose & Manum (1990, p. 39) is not depressed (Table 1). The closest resemblance exists between the new Spanish material and members of Mirovia Reymano´wna emend. Bose & Manum (1990, p. 64). However, six out of eight Mirovia species have leaf lengths of less than 15 mm (Table 1). The two other species are distinguishable from M. gothanii by: (1) the presence of longer ‘finger-like’ papillae on the projecting margins in Mirovia persulcata (Johansson) Bose & Manum, and (2) the absence of a projecting or papillate groove (see Manum, 1987, table 2 and Bose
767
& Manum, 1991, table 1 respectively) in Mirovia sibirica (Samylina) Bose & Manum. According to the illustrations in Gothan (1954), Sciadopitytes sp. from the Lower Cretaceous of Santa Maria de Meia` are in accordance with the specimens described here in many features: (1) width of the leaves (1.7–2.2 mm); (2) width of the stomatal groove (0.4–0.5 mm; Gothan, 1954, figs 1–2); (3) occurrence of an obtuse, emarginate apex (top of fig. 2 in Gothan, 1954) or with its mucron preserved (on the right of fig. 1 in Gothan, 1954); (4) stomatal groove weakly covered by margins (up to 70 m); (5) stomatal density about 150 stomata per mm2; (6) high density of papillae (fig. 4 in Gothan, 1954); and (7) short papillae (1.5–3.5 m long) rounded at their top (fig. 5 in Gothan, 1954). This new assignation of Gothan’s (1954) specimens was also proposed by Manum et al. (2000) who suggested close affinities with M. persulcata. Remarks. The linear leaves of Mirovia gothanii share several characters with the modern Sciadopitys verticillata: (1) the stomatal area is restricted to a more or less protected groove, and (2) each non-stomatal cell and each subsidiary cell of the stomatal strip bears one papilla, and these papillae protect the stomata (Halle, 1915, p. 511; Reymano´wna, 1985, p. 8). The leaves of Sciadopitys verticillata are, however, of two types: (1) brown, scale-like leaves spirally-arranged along the axis or disposed in very tight false whorls in the distal part, and (2) linear leaves with a single stomatal groove borne by small dwarf twigs. These ‘symphyllodes’ would have originated from the fusion of two leaves, the groove corresponding to the junction of their lower sides (Meyen, 1987, p. 212). Bose & Manum (1990, p. 17) found no evidence in the morphology of Mirovia leaves or shoots that favour such a phenomenon. In contrast to Sciadopitys verticillata, the leaves of M. gothanii are not dimorphic in venation or in stomatal distribution. None of the miroviaceous species possesses the leaves borne by small dwarf twigs or the pseudo-whorled leaf arrangement present in Sciadopitys verticillata (Bose & Manum, 1990, p. 14; Taylor & Taylor, 1993, p. 712), but evidence from denuded stems, leafy twigs, and the character of the
Figure 3. Mirovia gothanii sp. nov., Lower–Middle Albian, Rubielos de Mora, Spain. A, stoma in external view showing short papillae around the mouth of the stomatal pit, MPZ 00/571;600. B, stomatal apparatus with seven subsidiary cells, MPZ 00/570;600. C, inside of the stomatal groove in external view with papillae, MPZ 00/571;320. D, two stomata in external view showing four and six subsidiary cells respectively around the guard cells, MPZ 00/570;600. E, projecting and overhanging stomatal groove margin with papillae, MPZ 00/571;320. F, non-projecting and non-overhanging stomatal groove margin with papillae, MPZ 00/571;750. G, resin canals in the leaf mesophyll, MPZ 00/569;60. H, SEM of a resin canal, MPZ 00/571;320.
768
Table 1. Comparison of the species belonging to the family Miroviaceae (modified from Bose & Manum, 1990, 1991 and Manum et al., 1991)
Characters/Taxa
Mirovia florinii Bose & Manum
Mirovia groenlandica Bose & Manum
Mirovia ineffecta Bose & Manum
Mirovia lagerheimii (Johansson) Bose & Manum
Mirovia persulcata (Johansson) Bose & Manum
Mirovia sibirica (Samylina) Bose & Manum
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
?
?
8–15 + +
7–15 + + +
L 7–10 + +
10–12 + + +
10–15 +
50+ ? + +
40+ ? +
+ +
+ + +
+ + +
+ ?
(+) +
(+)
+ + (+)
+ + + (+)
+ + +
Location
Spitsbergen
Spitsbergen, Baffin Island
West Greenland
Spitsbergen, Baffin Island
northern Norway
northern Norway
Siberia
Age
Barremian–Aptian
Barremian–Aptian
Barremian–Aptian
Barremian–Aptian
Bajocian–Bathonian
Bajocian–Bathonian
Early Cretaceous
References
Bose & Manum (1990)
Bose & Manum (1990)
Bose & Manum (1991)
Bose & Manum (1990)
Johansson (1920); Florin (1922); Sveshnikova (1981); Manum (1987); Bose & Manum (1990)
Johansson (1920); Florin (1922); Sveshnikova (1981); Manum (1987); Bose & Manum (1990)
Samylina (1963); Sveshnikova (1981); Manum (1987); Bose & Manum (1990)
B. Gomez
Decurrent leaf base Hole in bottom of leaf Stomatal zone in groove Stomatal zone not in groove Stomata irregularly arranged Stomata in files or bands Furrow in upper surface Leaf dimorphism documented Stems, denuded (D) or leafy (L) Length of leaf (mm) Resin ducts Groove margin papillate Stomata orientated longitudinally Stomata orientated transversely Stomata orientated obliquely Stomata randomly arranged Subsidiary cells papillate Margins projecting over stomatal groove Papillae towards groove longer Non-stomatal cells inside groove with papillae
Mirovia capbohemanensis Bose & Manum
Table 1. Continued
Characters/taxa
Mirovia szaferi (Reymano´wna) Bose & Manum =type species
Mirovia gothanii sp. nov.
+
+
+
+ +
Oswaldheeria macrophylla (Florin) Bose & Manum
Oswaldheeria scotica (Florin) Bose & Manum
Holkopitys hoegii Bose & Manum
+
+
+
+
+
+ +
+ + (+) + + D 10–20 + +
+ + (+) +
+ +
+
50 + +
90 + +
15–20 ? +
+ +
+ +
+
+ +
+
+ +
10–14 + ? +
50+ + + +
8–15(22) + +
(+)
(+)
+ + +
+
+ ?
Location
Poland
Spain
Baffin Island, Spitsbergen
West Greenland, Baffin Island, Spitsbergen
northern Norway
Scotland
Baffin Island, Spitsbergen
Age
Early Bathonian
Albian
Barremian–Aptian
Barremian–Aptian
Bajocian–Bathonian
Late Jurassic
Barremian–Aptian
References
Reymano´wna (1985); Bose & Manum (1990)
herein
Bose & Manum (1990)
Florin (1922); Bose & Manum (1990)
Florin (1922); Sveshnikova (1981); Manum (1987); Bose & Manum (1990)
Florin (1922); Bose & Manum (1990)
Bose & Manum (1990)
A new species of Mirovia from Spain
Decurrent leaf base Hole in bottom of leaf Stomatal zone in groove Stomatal zone not in groove Stomata irregularly arranged Stomata in files or bands Furrow in upper surface Leaf dimorphism documented Stems, denuded (D) or leafy (L) Length of leaf (mm) Resin ducts Groove margin papillate Stomata orientated longitudinally Stomata orientated transversely Stomata orientated obliquely Stomata randomly arranged Subsidiary cells papillate Margins projecting over stomatal groove Papillae towards groove longer Non-stomatal cells inside groove with papillae
Oswaldheeria arctica Bose & Manum
Oswaldheeria hallei (Florin) Bose & Manum
769
770
Table 1. Continued
Characters/taxa
+ +
Sciadopityoides greenboana Watson et al.
Sciadopityoides ikorfatensis Bose & Manum
Sciadopityoides microphylla (Heer) Bose & Manum
Sciadopityoides nathorstii (Halle) Sveshnikova
Sciadopityoides ukrainensis Doludenko & Sveshnikova
Sciadopityoides uralensis (Dorofeev & Sveshnikova) Sveshnikova
Sciadopityoides variabilis (Bose) Sveshnikova
+ (+) +
+ +
+ +
+ +
+ +
+ +
+ +
+
+
+
+
+
+ + L 13–18
+
?
?
+ (+)
+ + + D 7–18 + +
+ ?
9 + +
+ +
+ +
10–14(20) +
D 40–50 + + +
(6)12–15(24)
+ +
+
(+)
(+)
+
+
+
(+) +
?
+
+ +
+
+
+
Location
West Greenland
England
West Greenland
Baffin Island, Spitsbergen, West Greenland
West Greenland
Western Ukraine
Urals
Baffin Island
Age
Barremian–Aptian
Berriasian– Hauterivian
Barremian–Aptian
Barremian–Aptian
Barremian–Aptian
Late Jurassic
Cenomanian– Turonian
Barremian–Aptian
References
Heer (1868, 1876); Halle (1915); Sveshnikova (1981)
Watson et al. (2001)
Bose & Manum (1990)
Heer (1876); Bose & Manum (1990)
Halle (1915); Sveshnikova (1981)
Doludenko (1963); Sveshnikova (1981); Manum (1987)
Dorofeev & Sveshnikova (1959); Doludenko (1963); Sveshnikova (1981); Manum (1987)
Bose (1955); Sveshnikova (1981)
B. Gomez
Decurrent leaf base Hole in bottom of leaf Stomatal zone in groove Stomatal zone not in groove Stomata irregularly arranged Stomata in files or bands Furrow in upper surface Leaf dimorphism documented Stems, denuded (D) or leafy (L) Length of leaf (mm) Resin ducts Groove margin papillate Stomata orientated longitudinally Stomata orientated transversely Stomata orientated obliquely Stomata randomly arranged Subsidiary cells papillate Margins projecting over stomatal groove Papillae towards groove longer Non-stomatal cells inside groove with papillae
Sciadopityoides crameri (Heer) Sveshnikova
A new species of Mirovia from Spain
leaf bases in detached leaves show that the leaves were spirally attached or horizontally spreading (e.g., Bose & Manum, 1991, p. 19). There is no evidence to suggest that small leaves (scale leaves) subtended large leaves (needles) as in the extant species. Moreover, the stomata of Sciadopitys verticillata adult leaves do not have the same structure (Watson & Harrison, 1998, fig. 16C) as those of the Miroviaceae and, in particular, show 8–13 (14) subsidiary cells (Florin, 1931; Lemoine-Se´bastian, 1972) in contrast, for example, to Mirovia gothanii which only displays 4–7 subsidiary cells. In accordance with the hypothesis of Bose & Manum (1990, p. 17) concerning Mirovia and Oswaldheeria, the decurrent tapered base and the leaf cushion of Mirovia gothanii suggest that the leaves of the latter could have been arranged horizontally. However it is difficult to ascertain whether they were deciduous like many other Mesozoic ‘Sciadopitys-like’ taxa mentioned above (Manum et al., 2000) or persistent, being only separated after the death of the shoot as observed in Taxus baccata L. (pers. obs.). The exact evolutionary relationships between extinct and extant gymnosperm families remain controversial and one may question whether the Miroviaceae are sufficiently distinct to be recognized as a separate family (Watson et al., 2001). Among the living conifers the closest affinities of the Miroviaceae are undoubtedly somewhere within the Cupressaceae sensu stricto, Sciadopityaceae or Taxodiaceae, which depending on systematic treatments, are considered to be three distinct families (Price, 1989; Page, 1990; Ohsawa, 1994), or two, with the Sciadopityaceae included as a subgroup of the Taxodiaceae (Hart, 1987; Stewart & Rothwell, 1993; Taylor & Taylor, 1993; Yao et al., 1997) or with the Taxodiaceae completely merged into the Cupressaceae sensu lato (Eckenwalder, 1976; Brunsfeld et al., 1994, Gadek et al., 2000). So, in the current state of the art, the assignation of ‘Sciadopitys-like’ fossil leaves to one or other of the extant families may introduce more confusion than clarity. Otherwise, the fossil record of conifers suggests that the Taxodiaceae originated during the Triassic and was well established by the Jurassic (Lemoigne, 1967; Miller, 1982; Yao et al., 1997), and that the Cupressaceae may have had its origin in this family (Alvin et al., 1982). Oxfordian taxodiaceous woods, along with known reproductive structures (Yao et al., 1997, 1998), reinforce the view that this family was well separated from Cupressaceae by the Middle Jurassic (Philippe, 1994). Whatever the phyletic history was, a few living cupressaceous and taxodiaceous taxa display acicular/linear leaves. Acicular leaves of Juniperus L. (Cupressaceae sensu
771
stricto) bear one (e.g., J. conferta Parl or rigida Sieb. & Zucc.) or two (e.g. J. communis L., drupacea Labille or oxycedrus L.) stomatal bands, but the stomata are never set in a groove as in Holkopitys, Mirovia and Sciadopityoides. Juniperus leaves generally remain attached to the stem even long after their death. In addition, living relatives of Juniperus (e.g., J. communis or oxycedrus) usually have strongly keeled leaves with well-developed sclerenchyma joining the adaxial and abaxial surface, which would probably be preserved during fossil diagenesis, but they have never been observed in the Miroviaceae. Within the Taxodiaceae, Athrotaxis selaginoides D. Don, Cunninghamia (Richard) Brown, Glyptostrobus Endlicher, Metasequoia Miki, Sequoia Endlicher, and Taxodium Richard have linear or lanceolate leaves. Taxodiaceae usually show amphistomatic leaves, except for Metasequoia glyptostroboides Hu & Cheng, with stomata arranged in bands or more exceptionally scattered in Athrotaxis cupressoides D. Don, Glyptostrobus lineatus (Poir.) Druce, and Sequoiadendron giganteum (Lindley) Buchholtz (Srinivasan & Friis, 1989). However, none of these has the typical single stomatal groove of the Miroviaceae and, thus, I am inclined here to prefer the genus Mirovia and the family Miroviaceae in the sense of Manum et al. (2000) rather than the Sciadopityoides form-genus concept of Watson et al. (2001). The Miroviaceae constituted a significant group in Early Cretaceous Arctic floras when the family reached its climax in terms of abundance and diversity (Manum, 1987, p. 21). Some sporadic occurrences extending into Eurasia are known from the mid-Jurassic–Late Cretaceous (Bose & Manum, 1990). Other data from the English Wealden have demonstrated the occurrence of the Miroviaceae in Western Europe: Sciadopitytes sp. nov. (31TaxodSc; Oldham, 1976, p. 462, pl. 73, figs 1–6) and Sciadopityoides greenboana Watson et al. (2001). Data from Rubielos de Mora now establish that its geographical expansion reached southern parts of the Northern Hemisphere (approximately the Albian 30N according to Smith et al., 1994), even below the present 40N postulated by Florin (1963) and Sveshnikova (1981). At Rubielos de Mora, as well as at Santa Maria de Meia`, Mirovia gothanii constituted a dominant component of the flora. There are likely to be palaeoecological and palaeoenvironmental explanations for the success of the family during the Early Cretaceous. Strong xeromorphic adaptations are expressed in the absence of stomata on the adaxial side while, on the abaxial cuticle, they are arranged close to each other in a single strip sunken into a groove with a protruding margin, and are protected by papillae. In Spain the success of M. gothanii may
772
B. Gomez
have been related to a unique set of climatic and edaphic conditions (Gomez et al., 1999, p. 673). On the other hand, as noted by Manum et al. (2000, pp. 226, 227), the apparent paradox of xeromorphic adaptations of the Miroviaceae in non-xeric habitats from Spain to the Arctic during the Jurassic– Cretaceous period can be interpreted as ‘a phylogenetically conservative feature of gymnosperms in general or more specifically as a functional adaptation to less efficient water conductive system’. Acknowledgements This research was supported by a European Community Marie Curie Fellowship (HPMF-CT-200201584), by UMR 5125 and the ECLIPSE programme of the French CNRS, and by Spanish Government projects BTE2001-0185-C02-01 and B052001-0173. I thank the referees and editor for their comments on the original manuscript. References Alvin, K. L., Dalby, D. H. & Oladele, F. A. 1982. Numerical analysis of cuticular characters in Cupressaceae. In The plant cuticle (eds Cutler, D. F., Alvin, K. L. & Price, C. E.), pp. 379– 396 (Academic Press, London). Bose, M. N. 1955. Sciadopitytes variabilis n. sp. from the Arctic of Canada. Norsk Geologisk Tidskrift 35, 53–68. Bose, M. N. & Manum, S. B. 1990. Mesozoic conifer leaves with ‘Sciadopitys-like’ stomatal distribution. A re-evaluation based on fossils from Spitsbergen, Greenland and Baffin Island. Norsk Polarinstitutt Skrifter 192, 1–81. Bose, M. N. & Manum, S. B. 1991. Additions to the family Miroviaceae (Coniferae) from the Lower Cretaceous of West Greenland and Germany: Mirovia groenlandica n. sp., Tritaenia crassa (Seward) comb. nov., and Tritaenia linkii Ma¨gdefrau et Rudolph emend. Polar Research 9, 9–20. Brunsfeld, S. J., Soltis, P. S., Soltis, D. E., Gadek, P. A., Quinn, C. J., Strenge, D. D. & Ranker, T. A. 1994. Phylogenetic relationships among the genera of Taxodaceae and Cupressaceae: evidence from rbcL sequences. Systematic Botany 19, 253–262. Doludenko, M. P. 1963. A new species of Sciadopitys from the Jurassic of western Ukraine. Paleontological Zhurnal 1963 (1), 123–126. [In Russian] Dorofeev, P. I. & Sveshnikova, I. N. 1959. On a find of remains of the genus Sciadopitys S. et Z. in Upper Cretaceous deposits of the Urals. Doklady Akademiya Nauk SSSR 128, 1276–1278. [In Russian] Eckenwalder, J. E. 1976. Re-evaluation of Cupressaceae and Taxodiaceae: a proposed merger. Madron˜o 23, 237–256. Florin, R. 1922. On the geological history of the Sciadopitineae. Svensk Botanisk Tidskrift 16, 260–270. Florin, R. 1931. Untersuchungen zur Stammesgeschichte der Coniferales und Cordaitales. Kungliga Svenska Vetenskapsakademiens Handlingar 3 10, 1–588. Florin, R. 1963. The distribution of conifer and taxad genera in time and space. Acta Horti Bergiani 20, 121–312. Gadek, P. A., Alpers, D. L., Heslewood, M. M. & Quinn, C. J. 2000. Relationships within Cupressaceae sensu lato: a combined morphological and molecular approach. American Journal of Botany 87, 1044–1057. Gomez, B., Barale, G., Martı´n-Closas, C., The´venard, F. & Philippe, M. 1999. De´couverte d’une flore a` Ginkgoales,
Bennettitales et Conife´rales dans le Cre´tace´ infe´rieur de la Formation Escucha (Chaıˆne Ibe´rique Orientale, Teruel, Espagne). Neues Jahrbuch fu¨r Geologie und Pala¨ontologie, Monatshefte 11, 661–675. Gomez, B., Martı´n-Closas, C., Barale, G. & The´venard, F. 2000. A new species of Nehvizdya (Ginkgoales) from the Lower Cretaceous of the Iberian Ranges (Spain). Review of Palaeobotany and Palynology 111, 49–70. Gomez, B., Martı´n-Closas, C., Barale, G., Sole´ de Porta, N., The´venard, F. & Guignard, G. 2002. Frenelopsis (Coniferales: Cheirolepidiaceae) and related male organ genera from the Lower Cretaceous of Spain. Palaeontology 45, 997–1036. Gothan, W. 1954. U } ber ein Massenvorkommen von Sciadopitytes Nadeln in Kohligen Ablagerungen des Oberen Jura oder Wealden der Spanischen Ost-Pyrena¨en. Svensk Botanisk Tidskrift 48, 337– 342. Halle, T. G. 1915. Some xerophytic leaf-structures in Mesozoic plants. Geologiska Fo¨reningens i Stockholm Fo¨rhandlingar 37, 493– 520. Harris, T. M. 1969. Naming a fossil conifer. In J. Sen Memorial Volume, pp. 243–252 (J. Sen Memorial Committee and Botanical Society of Bengal, Calcutta). Harris, T. M. 1979. The Yorkshire Jurassic Flora, Volume 5. Coniferales, 166 pp. [British Museum (Natural History), London]. Hart, J. A. 1987. A cladistic analysis of conifers: preliminary results. Journal of the Arnold Arboretum 68, 269–307. Heer, O. 1868. Flora fossilis Arctica, I. Die fossile flora der Polarla¨nder, 192 pp. (Schulthess, Zu¨rich) Heer, O. 1876. Flora fossilis Arctica, IV, part 1. Beitra¨ge zur fossilen Flora Spitzbergens. Kungliga Svenska VetenskapsAkademiens Handlingar 14 (5), 1–144. Johansson, N. 1920. Neue mesozoische Pflanzen aus Ando¨ in Norwegen. Svensk Botanisk Tidskrift 14, 249–257. Lemoigne, Y. 1967. Pale´oflore a` Cupressales dans le Trias–Rhe´tien du Contentin. Comptes Rendus de l’Acade´mie des Sciences (Paris) 264, 715–718. Lemoine-Se´bastian, C. 1972. Structures e´pidermiques chez Sciadopitys et interpre´tation des organes. Bulletin de la Socie´te´ Botanique de France 119, 61–74. Manum, S. B. 1987. Mesozoic Sciadopitys-like leaves with observations on four species from Andøya, northern Norway (Jurassic) and emendation of Sciadopityoides Sveshnikova. Review of Palaeobotany and Palynology 51, 165–168. Manum, S. B., Bose, M. N. & Vigran, J. O. 1991. The Jurassic flora of Andøya, northern Norway. Review of Palaeobotany and Palynology 68, 233–256. Manum, S. B., van Konijnenburg-van Cittert, J. H. A. & Wilde, V. 2000. Tritaenia Maegefrau et Rudolf, Mesozoic ‘Sciadopityslike’ leaves in mass accumulations. Review of Palaeobotany and Palynology 109, 255–269. Meyen, S. V. 1987. Fundamentals of palaeobotany, 432 pp. (Chapman and Hall, London). Miller, C. N. 1982. Current status of Paleozoic and Mesozoic conifers. Review of Palaeobotany and Palynology 37, 99–114. Ohsawa, T. 1994. Anatomy and relationships of petrified seed cones of the Cupressaceae, Taxodiaceae and Sciadopityaceae. Journal of Plant Research 107, 503–512. Oldham, T. C. B. 1976. Flora of the Wealden plant debris beds of England. Palaeontology 19, 437–502. Page, C. N. 1990. Pinatae. In The families and genera of vascular plants, vol. I, Pteridophytes and gymnosperms (eds Kramer, K. U. & Green, P. S.), pp. 290–348 (Springer-Verlag, Berlin). Philippe, M. 1994. Radiation pre´coce des conifers Taxodiaceae et bois affines du Jurassique de France. Lethaia 27, 67–75. Price, R. A. 1989. An immunological comparison of the Sciadopityaceae, Taxodiaceae, and Cupressaceae. Systematic Botany 14, 141–149. Querol, X., Salas, R., Pardo, G. & Ardevol, L. 1992. Albian coal-bearing deposits of the Iberian Range in north-eastern Spain. Geological Society of America, Special Paper 267, 193–208.
A new species of Mirovia from Spain Reymano´wna, M. 1985. Mirovia szaferi gen. et sp. nov. (Ginkgoales) from the Jurassic of Krako´w region, Poland. Acta Palaeobotanica 25, 3–12. Samylina, I. N. 1963. The Mesozoic flora of the lower reaches of the Aldan river. Trudy Botanicheskiy Institut Akademiya Nauk SSSR, Serya 8, Paleobotanica 4, 205–229. [In Russian] Schimper, W. Ph. & Schenk, A. 1890. Zittel’s Handbuch der Palaeontologie II, 958 pp. (Abteilung Palaeophytologie Verlag von R. Oldenburg, Mu¨nchen/Leipzig) Smith, A. G., Smith, D. G. & Funnell, B. M. 1994. Atlas of Mesozoic and Cenozoic coastlines, 99 pp. (Cambridge University Press, Cambridge). Stewart, W. N. & Rothwell, G. W. 1993. Paleobotany and the evolution of plants, 521 pp. (Cambridge University Press, Cambridge). Sveshnikova, I. N. 1981. The new fossil genus Sciadopityoides (Pinopsida). Botanicheskiy Zhurnal 66, 1721–1729. [In Russian] Taylor, T. N. & Taylor, E. L. 1993. The biology and evolution of fossil plants, 982 pp. (Prentice Hall, Englewood Cliffs, NJ) Watson, J. 1988. The Cheirolepidiaceae. In Origin and evolution of gymnosperms (ed. Beck, C. B.), pp. 382–447 (Columbia University Press, New York).
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Watson, J. & Alvin, K. L. 2000. The cheirolepidiaceous conifers Frenelopsis occidentalis Heer and Watsoniocladus valdensis (Seward) in the Wealden of Germany. Cretaceous Research 20, 315–326. Watson, J. & Harrison, N. A. 1998. Abietites linkii (Ro¨mer) and Pseudotorellia heterophylla Watson: coniferous or ginkgoalean? Cretaceous Research 19, 239–278. Watson, J., Lydon, S. J. & Harrison, N. A. 2001. A revision of the English Wealden Flora, III: Czekanowskiales, Ginkgoales and allied Coniferales. Bulletin of the Natural History Museum, London (Geology) 57, 29–82. Yao, X., Taylor, T. N. & Taylor, E. L. 1997. A taxodiaceous seed cone from the Triassic of Antarctica. American Journal of Botany 84, 343–354. Yao, X., Zhou, Z. & Zhang, B. 1998. Reconstruction of the Jurassic conifer Sewardiodendron laxum (Taxodiaceae). American Journal of Botany 85, 1289–1300. Ziegler, A. M., Raymond, A. M., Gierlowski, T. C., Horrell, M. A., Rowley, D. B. & Lottes, A. L. 1987. Coal, climate and terrestrial productivity: the present and Early Cretaceous compared. In Coal and coal-bearing strata: recent advances (ed. Scott, A. C.), Geological Society, London, Special Publication 32, 25–49.