Permian Glossopteris and Eiatocladus megafossil floras

Antarctic Science I (1): 35-44 (1989)

Permian Glossopteris and Eiatocladus megafossil floras from the English Coast, eastern Ellsworth Land, Antarctica CAROLE T. GEE Swiss Federal Institute of Technology in Zurich, Geological Institue, ETH-Zearum,CH-8092 Zurich, Switzerland

Abstract: Plant megafossils collected from the previously unexplored English Coast of eastern Ellsworth Land have yielded the first Glossopteris leaves from the Antarctic Peninsula tectonic province. Collecting at Erehwon Nunatak recovered numerous spatulate leaves of consistent morphology, most likely pertaining to one natural species, and described here as Glossopteris erehwonensis sp. nov., as well as fragments of Phyllotheca and Equisetum. The large sample size, the predominanceof Glossopterisleaves, the low species diversity, and the lack of characteristic Early Permian (Gangamopteris)and Early Triassic (Dicroidium, kpidopteris, Pleuromeia) taxa suggest a Permian, probably Late Permian, age for the Erehwon Nunatak beds. These rocks are thus significantly older than any other sedimentary rocks known from Palmer Land and Ellsworth Land. A second flora, collected from Henkle Peak, consists exclusively of the remains of Elatocladusplanus, a conifer which probably dominated forests in this area during the Jurassic. The plant megafossils support correlation of the sedimentary rocks with those of the Middle-Late Jurassic Latady Formation of south-eastern Antarctic Peninsula and eastern Ellsworth Land. Received 19 September 1988, accepted 12 December 1988

Key words: Elatocladus, Ellsworth Land, Glossopteris, palaeobotany, Permian. geology of the area has been discussed in preliminary reports (O’Neill & Thomson 1985, Rowley et al. 1985, Laudon et al. 1987). Fossilplantsare foundat threeoutcrops: Erehwon Nunatak, Henkle Peak, and Mount Goodman (Fig. 1). The remains of Glossopteris,Phyllotheca, and Equisetum occur in the dark, fine-grained,volcanogenic sedimentaryrocks of the Erehwon beds, of which approximately2 m are exposed at Erehwon Nunatak. The coniferous material collected from exposures on the south-west side of Henkle Peak and the single fern specimen from Mount Goodman come from the dark, fine-grained, volcanogenic sedimentary rocks of the Middle-Late Jurassic Latady Formation (Laudon in press, Rowley et al. in press). The fossil leaves from both sites are preserved as compressions and impressions without any carbonaceous film or cuticle remaining. Because the contrast between matrix and specimens is often poor, photographs of the plants are supplementedhere with line drawings. The wood remains from Henkle Peak are preserved as petrifications in which the internal structure was diagenetically obliterated; polished sections of several specimensand cellulose acetate peels made from one particularly promising piece revealed no internal structure. However, many of the specimens do externally resemble pieces of wood with bark. Plant microfossils (i.e. pollen, spores and dinoflagellates) could not be extracted from sediment samples from Erehwon Nunatak. The specimensare housed in thePaleobotanicalCollection of the University of Texas at Austin. Many of the rocks lack fossils. Among those with fossils identifiabletogenus, more

Introduction Glossopteris leaves are ubiquitous in Permian sediments throughout Gondwana. The Permian coal measures in East Antarctica (Cridland 1963, Plumstead 1964, Townrow 1967a, Schopf 1968, overview by Rigby & Schopf 1969) and the Permian Polarstar Formation in West Antarctica (Taylor & Smoot 1985, Collinson et al. in press) are no exception. Until recently, however, glossopterid remains have never been reported from the AntarcticPeninsulatectonicprovince (terminology after Laudon et al. 1987). During the austral summer 1984-85, a US Geological Survey expedition uncovered the first Glossopteris leaves from the previously unexplored English Coast. Twigs and isolated needles of Elatocladus and fossilized wood were found at another site nearby. The fossil plants are of special interest as they are one of the few biostratigraphic means by which the sedimentary rocks along the English Coast can be dated. Although they were briefly mentioned in papers on the sedimentology, petrography, and tectonic setting of the area (Laudon et al. 1987,Laudon in press, Rowley et al. in press), the taxonomy and morphology of the plants from the two sites have not been fully described until now.

Geological setting The English Coast is located in north-eastern Ellsworth Land, directly west of the Antarctic Peninsula (Fig. 1). The

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Fig. 1. Map of the Antarctic Peninsula, showing the Erehwon Nunatak (E), Henkle Peak (H), and Mount Goodman (M) fossil plant localities on the English Coast.

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than 60 specimens bearing numerous Glossopteris leaves were collected from Erehwon Nunatak; in these specimens, stem andleaffragmentsof Phyllorhecaare common whereas those of Equiseturn are few. Approximately 20 specimens bearing Elatocladus remains were collected from Henkle Peak. One specimen bearing a single Cladophlebis pinna was collected from Mount Goodman, northern Behrendt Mountains.

Discussion. Phyllotheca commonly occurs as fragments of leafy shootsas well as isolated whorls of leavesintermixed with the Glossopteris leaves. The stems are much more slender and the leaves finer than those of Equisetum. Stratigraphical range. Phyllotheca ranges from the Pennsylvanian to the Cretaceous, although it is most abundant in the Permian (Boureau l W , Taylor 1981). Phyllotheca is also known from other Permian rocks in Antarctica(Rigby 1969).

1. Erehwon Nunatak

Systematic palaeontology Division SPHENOPHYTA Order EQUISETALES Family PHYLLOTHECACEAE Genus PHYLLOTHECA Brongniart emend. Townrow 1956 Phyllotheca sp. Fig. 2a, d Description. Slender shoots 3-4 cm wide, with 6-20 leaves per node. Leaves relatively long and narrow, up to 11 mm long and 0.3 mm wide, linear in shape, presumably fused slightly at their base, free and spreading from the stem for most of their length. Venation not evident.



Family EQUISETACEAE Genus EQUISETUM Linnt 1753 Equisetum sp. Fig. 3 Description. Compressed stem up to 13 mm in width, constricted at the node to 3 mm. Leaf sheath comprised of 12 or more leaves (6 apparent on one side). Leaves long and narrow, about 13 mm long and 0.5 mm wide, linear in shape, fused together only at the base but remaining appressed to the stem, each tapering evenly to a subacute apex. Midvein distinct, one per leaf. Discussion. Although Equisetum is represented by only a few small fragments of the stem and leaf sheaths, it can be readily distinguished from Phyllotheca by the size, shape

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PLANT MEGAFOSSILS FROM THE ENGLISH COAST

Fig. 2. Fossil plants collected from the English Coast; see text for exact locality information. a. Leaf whorl of Phyllotheca sp., x 3. [270: UTPC.] b. Small leaf of Glossopteris erehwonensis sp. nov., x 2. [271: UTPC.] c. Detached needles and leafy twig of Elatoctadus planus (Feistmantel) Seward; note that the leaf tips of the twig are tom away, altering the natural shape of the leaves, x 1. [272: UTPC.1 d. Compressed stem of Phyllotheca sp.; note whorls of long linear leaves, x 2. [273: UTPC.] e. Scale leaf associated with Glossopteris erehwonensis sp. nov., x 2. [274: UTPC.] f & g. Part and counterpart of a detached leaf of Glossopteris erehwonensis sp. nov., x 1. [Holotype; 274: UTPC.] h. CIadophlebis antarctica Halle, x 2. [275: UTPC.]

and arrangement of the leaves. Not enough material is present for identification to the species level. The name Equisetum is generally applied to fossil remains resembling the extant genus which may have been formerly referred to as Equisetites. Fossil Equisetum has not been found to differ significantly in morphology from modem Equisetum (Harris 1961, Gould 1968). Stratigraphical range. Although the genus reaches its greatest diversity during the Triassic, reports of Equisetum (or ‘Equisetites’)range from thecarboniferous to the present (Taylor 1981) and are known from the Gondwana Permian (Anderson & Anderson 1985).

Fig. 3. Sketch of a leaf sheath fragment of Equisetwn sp. [276: UTPC.]



Division FTERIDOSPERMOPHYTA Order GLOSSOPTERIDALES Family unknown Genus GLOSSOPTERISBrongniart emend. Pant & Gupta 1968 Glossopteris erehwonensis sp. nov. Figs 2b, e, f, g, 4 , 5

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Diagnosis. Leaf spatulate,widest point about one-fifthof leaf length down from apex, tapering strongly toward leaf base with lamina acutely decurrent along petiole. Leaf small, usually less than 12 cm long, and variable; in larger leaves, length to width ratio about 5 : 1. Apex rounded but angular at the very tip. Petiole robust, truncate at base. Midrib wide at base, narrowing distally but strong and persistent to apex. Lateral veins arising from midrib at acute angles, arching back, then continuing at angles between 30" and 40" to the margins. Lateral vein density near centre of lamina between margin and midrib approximately 28-30 veins per cm. Description. Detached leaves, simple and entire, distinctly spatulate (= narrowly oblanceolate) in outline, widest about one-fifth of the leaf length down from the apex, tapering strongly toward the base, lamina acutely decurrent along petiole 10-15 mm. Leaf relatively small; lengths variable, ranging from 2 to 14 cm, usually 9 to 10 cm (length to width ratio in larger leaves about 5 : 1). Apex rounded, angular at very tip. Petiole relatively robust, flattened in the plane of the lamina, clearly truncate at base. Midrib multi-stranded, wide at base, narrowing distally as lateral veins separate off, but clearly persistent to the apex. Secondary venation clearly reticulate (Fig. 5), composed of lateral veins arising from the midrib at very low angles, arching back slightly, continuing at angles between 40" and 50", dichotomizing and anastomosing, persisting to the margins. Density of lateral veins about 28-30 per cm. Holofype. University of Texas PaleobotanicalCollection no. 274. Part and counterpart figured here as Fig, 2f and g. Type locality. Erehwon beds of Erehwon Nunatak (74'313, 76"25'W), eastern Ellsworth Land. Etymology. Derived from the name of the collecting site, Erehwon Nunatak. Discussion. Although the leaves vary in size, they all share the same morphology: a characteristicspatulate shape, a strong and persistent midrib, and acutely decurrent lamina along a robust petiole (Fig. 4). As a result of their morphological similarity and because variation in leaf size is a common feature even among leaves attached to the same shoot (Plumstead 1958, Pant & Singh 1974), the leaves are all assigned to the same species. As listed above, the charactcrs that bind together the leaves as a single species also separate this species from all other species of Glossopteris. Particularly useful papers for surveying glossopterid remains include the comprehensive monographs by S haila Chandra & Surange (1979) for India and by Anderson & Anderson (1985) for southern Africa and the species lists compiled by Rigby & Schopf (1969) for Antarctica, by Archangelsky & Arrondo (1969) and Archangelsky (1970) for South America, and by Gould (1975) for Australasia. With the profusion of Glossopieris species names in the literature, designating a new species may seem superfluous. In this case, however, the merits of this move outweigh the disadvantagesfor three major reasons. First of all, the great



b

Fig. 4. Sketches of selected leaves of Glossopteris erehwonensis sp. nov., showing the size range evident in the assemblage. Note that the spatulate shape of the leaf, its strong and persistent midrib, acutely decurrent leaf base, and robust petiole are constant regardless of size. a. One of the smallest leaves. [271: UTPC.] b. Holotype, a leaf of average size. [274: UTPC.] c. The apex of one of the largest leaves joined to the complete leaf base and petiole of another leaf of similar size; the square indicates the region of the leaf from which the drawing of the venation in Fig. 5 was made.

[277: UTPC.]

number (more than 60 specimens) of Glossopteris leaves from Erehwon Nunatak provides a large sample size. The consistency of morphological characters in the leaves, regardless of size, suggeststhat the leaves belonged to one or more individuals of a natural group. The intrinsic value of having a large natural group of Glossopteris leaves would be lost if it were submerged into an artificial form species. Secondly,most other speciesof Glossopteris are known only from fragmentary leaves and do not offer a sound basis for comparison. Thirdly and most importantly, because of the unusual

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5 mm

Fig. 5. Detailed sketch of the venation of Glossopteris erehwonensis sp. nov., showing the reticulum formed by the dichotomizing and anastomosing of the lateral veins; a magnified view of the uppermost leaf in Fig. 4c. [277:

UTPC.]

combination of spatulate shape and small size, the Erehwon leaves do not resemble any other Glossopteris species, with the exception of G. zeiileri. Although small Glossopteris leaves (e.g. G . angustifolia, G. decipens, G. nakkarea, G. tenuifolia, G . vulgaris, G . recurva) are generally similar in size and venation, they differ from G. erehwonensis in the basic character of leaf shape; the leaves of these species are linear or lorate, not spatulate, in shape. Differencesbetween leaf shape are particularly evident on pl. 42 in Shaila Chandra & Surange (1979) on which almost all of these speciesare drawn to the same scale for comparativepurposes. The spatulate shape of G. zeilleri, almost identical to that of G. erehwonensis, srandsoutasdistinctlydifferent. Although nearly identical in size and shape,Glossopteriszeilleri (Pant &Gupta 1968,ShailaChandra&Surange 1979)differs from G. erehwonensis in that its midrib fades away in the apical one-fourthof the leaf whereas the English Coast leaves each has a strong midrib that persists to the apex. This persistent midrib is clearly marked even in the smallestleaves (Figs 2b, 4a). Additionally, since nothing is known of leaf size and shape variation within G. zeilleri and nothing is known of the cuticle of G. erehwonensis, it would be difficultto merge the two species. At Erehwon Nunatak, solitary and fragmentary G. erehwonensis leaves were found in several beds of the exposed sequence. In one bed, however, the leaves occurred



in layered accumulations, about 7 cm thick, resembling leaf litter on a forest floor (Laudon et al. 1987, fig. 2a). Such accumulations of leaves are characteristic of glossopterid leaves found at other sites. Plumstead (1958, p. 82) interpreted these depositsas ‘normal autumnal deposits from deciduous plants’. The annually deciduous habitat of Glossopteris is supported by the numerous leaves found in autumn-winter varved sediments but not in spring-summer layers (Rerallack 1980). Accompanying the Glossopteris leaves are smaller leaves which differ slightly in size and shape from one another, Such scale leaves, commonly associated with glossopterid leaves, have recently been found to be borne by the reproductive structures of Glossopteris (e.g. Lacey et al. 1975, ShailaChandra& Surange 1977a,6, White 1978). Allofthe scale leaves from Erehwon Nunatak are entire, narrowly triangular in shape with an acute apex and a truncated or rounded base. The largest-scale leaf (Fig. 2e) is at least 1.5 cm in length and 0.5 cm in width, although there are some leaves that are considerably smaller (about half the size). The veins, extending from the base and persistent to the margins, form a reticulum but do not organize into a midrib. In general size, shape and venation, these scale leaves closely resemble those figured as Eretmonia-type scales by Shaila Chandra & Surange (1977b, text figs 1 6 1 ) in which the stalks of the scales are missing. Eretmonia is a genus designated for male fructifications associated with Glossopteris that are composed of stalked fertile leaves, variable in size and shape, which bear stalked clusters of sporangia (genus emendation in Lacey er al. 1975, p. 378). Due to the unfortunate lack of fructifications, attached or detached, in the English Coast material,one can only speculate that the scale leaves found with the vegetative leaves of Glossopteris erehwonensis may have been similarly borne by the reproductive parts of this plant. The only plants accompanyingthe glossopteridremains in the Erehwon beds are Phyllotheca and Equisetum. Although the remains of these sphenophytesin the assemblageare too poor to allow identification to the species level, it is not surprisingthat thoseof G. erehwonensis are well represented and moderately well preserved given the durable nature of Glossopteris leaves. Palaeoecology At the time of deposition of the Erehwon beds, parts of the English Coast were probably covered with deciduous woodlands or forests dominated by Glossopteris trees and resembling the reconstructedlandscapetypical of the Southern Hemisphere during much of the Permian, as beautifully illustrated by Thomas (1981). The extent of the woodland or forest along the English Coast remains, however, unclear. Around bodies of fresh water or near the roots of the

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Glossopteris trees (cf. Archangelsky 1986) were reed-like stands of small sphenophytes such as Phyllotheca and Equisetum. In a more substantial palaeoecological study, Cuneo (1983) reconstructed Early Permian Glossopteris communitiesgrowing on floodplainsas being dominated by colonizing conifers, glossopterids, and cordaites, with sphenophytes and arborescent lycopods in restricted subenvironments. Age of the Erehwon Nunatakjlora Correlation with other Glossopteris floras in other parts of Gondwana suggests that the Glossopteris-bearing beds of Erehwon Nunatak are Permian, probably Late Permian, in age. This age determination is primarily supported by the composition of the flora: the predominanceof Glossopteris leaves, the low species diversity, and the lack of taxa characteristic of Early Permian (e.g. Gangamopteris) and Early Triassic (e.g. Dicroidum, Lepidopteris, Pleuromeia) floras in Gondwana. All of these features characterizemegafossil assemblages in the Late Permian throughout Gondwana (Schopf & Askin 1980,Archangelsky 1986). In most Early Permian megafossil floras, the glossopterid leaves of Gangamopteris dominate even though those of Glossopteris may also occur. The proportion of Gangomopteris to Glossopteris shifts as time progresses until Gangamopteris disappears completely and Glossopteris dominates the floras. Sphenophytes (e.g. Phyllotheca, Sphenophyllum, Annularia) comprised an important part of the Gondwana floras throughout the Permian; they played an especially prominent role in some Late Permian floras (Plumstead 1973, Anderson & Anderson 1985). In the Erehwon Nunatak flora, with the exception of the sphcnophytic remains, the only fossils found are leaves of Glossopteris; there is no evidence of Gangamopteris. The low species diversity in the Erehwon Nunatak flora (three species) seems to be symptomatic of other Late Permian floras from high palaeolatitudes (e.g. Townrow 1967~).The ‘typically southern, with strong endemism’ 135)of theseGlossopterischaracter (Archangelsky 1986,~. dominated floras was probably controlled by the biological isolation imposedby the high latitudes (i.e. lack of migrating taxa), the restrictions of climate (probably cold-temperate) and local ecological limitations (Archangelsky & Arrondo 1969, Archangelsky 1986). The seed ferns Dicroidium and LRpidopteris and the lycopod Pleuromeia typify and dominate the Lower Triassic in Gondwana (Schopf & Askin 1980, Anderson & Anderson 1985). When glossopterid leaves are found associated with these plants, they make up only a small part of the flora (e.g. Anderson & Anderson 1985,Pant&Pant 1987). Thelack of Triassic elements in the Erehwon flora suggests that the Glossopteris-bearingbeds are older than Triassic. In the analysis of the composition of a flora, one must



consider the roleof taphonomicbias producedby differential preservation or by the local distribution of certain species. For example, one would assume that the preservation potential of leathery Gangamopterisleaves and of robust Dicroidium and LRpdopteris fronds would be similar to thatof Glossopkris, that is, the tough leaves of all of these plants would have the same, high preservationpotential. If these other species had been present in the flora, their remains should have been preserved along with the Glossopteris leaves and should have shown up as one or some of the many specimens collected, especially considering the substantial size of the collection. Similarly,the presence of plants in the flora with lower preservation potential should have also been documented by one or a few of the many specimens collected. In the absence of pollen and spores, which have a greater areal distribution than leaves, the patchiness of the local flora cannot be determined.

2. Henkle Peak Systematic palaeontology Division CONIFWZOPHYTA Order CONIFERALES Family unknown Genus ELATOCLADUS Halle emend. Hanis 1979 Elatocladus planus (Feistmantel) Seward 1918 Fig. 2c

Description. Known from detached needles, leafy twigs at least 4 cm long, and stem axes up to 20 cm in compressed width, all associated together. Leaves helically arranged about the stem although dorsoventrally flattened in one plane, slightly decurrent,closely spaced but not overlapping, free and spreading from the stem at right angles; leaf morphology long and linear with an acute, symmetrical apex,rangingfrom 1.5cm (neartwigapex) to8cm(detached needles) in length, and over 1 mm in width, with a single, distinct midvein extending the length of each leaf. Discussion. The salient features of these leafy twigs that are identicalto those of Elatocladusplanus known elsewhere are the size and shape of the needles and their attachment to the twig axis. Elatocladus planus is the name applied to long, unbranched shoots with long, narrow, bilateral leaves, strongly flattened into one plane and whose cuticle and reproductiveparts remain unknown (Townrow 19676). When found with cones and cuticle, shoots with Elatocladus planustype leaves have been assigned to the genus Rissikia (Townrow 1967b,White 1981,Anderson &Anderson 1985). Although the leafy shoots of Rissikia are morphologically similar to those of Elatocladus planus, Townrow (1967b, p. 121) advocated keeping the two taxa apart until the cuticular detai1sofE.planusareknown. Asalsopointedoutby White (1981), E. planus may be comprised of more than one natural species. Rissikia, known from the Middle Triassic (e.g. Gould

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1975, Retallack 1977, 1980) and Jurassic (White 1981) of eastern Australia and from the Late Triassic of South Africa (Townrow 1967b, 1969, Anderson & Anderson 1985), is assigned to the Podocarpaceae on the basis of associated reproductivematerial. Rissikia talbragarensis, for example, is envisaged as one of the coniferous trees comprising the Jurassic 'Kauri Pine' forest in New South Wales (White 1981, p. 696). Although E. planus at HenklePeak cannot be merged into any of the known species of Rissikia, the morphological similaritybetween the taxa suggests that E. planus may also have some affinity to arborescent podocarps. At Henkle Peak, a tree-like growth habitat for E.planus is supportedby the abundance of wood collected from the south-westem side of Henkle Peak. These structureless petrifications are commonly associated with twigs and isolated needles of E. planus. Although not found in organic attachment, it is highly probable that the wood and foliagepertain to the same plant based on constant association in a low diversity flora. It may thus be deduced from the abundance of wood, branches, and leaves collected from Henkle Peak, that E. planus was probably a large and arborescent,forest-forming conifer. On the Antarctic Peninsula, Elatocladus planus also occurs in the Middle-Late Jurassic Latady Formation on the Orville Coast (Gee 1984). Known mostly from Jurassicsedimentary rocks in the Southern Hemisphere, it also occurs in South America (Arrondo 1972, Petriella & Arrondo 1984), India (Feistmantell879,1882,Seward 1918,Sahni 1928,Sitholey 1944, Baksi 1968) and Australasia (Shirley 1902, Walkom 1917, 1919, 1921, Townrow 1967b). Formal synonymies are given in Townrow (19676, p. 119) and in Petriella & Arrondo (1984, p. 36). Stratigraphical range. Elatocladus planus ranges from the beginning of the Early Jurassic to the end of the Late Jurassic (Townrow 1967b, p. 121).

Palaeoecology Four of the five fossiliferous exposures at Henkle Peak yielded abundant remains of Elatocladus planus only (if wood is included). As may be deduced from the monospecific nature of the specimens,much of the Henkle Peak area was probably covered with forests of the arborescent conifer E. planus at the time of deposition. A similar example of a forest community made up almost exclusively of E. planus is also known from the Orville Coast (Gee 1984).

Age ofthe Henkle Peakflora Given the stratigraphical range of Elatocladus planus, the sedimentary rocks are most likely Jurassic in age. If, however, the Late Triassic age of the comparable Rissikia



media were also considered, the Henkle Peak flora could possibly be Late Triassic. A Jurassic age, however, is more probable as it would be in accordance with the age of the flora of greatest geographic proximity, the Orville Coast flora (Latady Formation),in which E. planus also dominates at one outcrop (Gee 1984). The MiddleLate Jurassic age of the Latady Formation was established by locally abundant invertebrate fossils (summarized in Laudon et al. 1983). 3. Mount Goodman

Systematic palaeontology Division PTERIDOPHYTA Order FILICALES Family unknown Genus CLADOPHLEBIS Brongniart 1849 Cladophlebis antarctica Halle 1913 Fig. 2h

Description. Detached pinna, over 7 cm long and about 2 cm wide, with pinnules slightly overlapping one another, regularly inserted at moderateangles to the pinna axis, linear and slightly falcate in shape with an acute apex, relatively long and narrow, up to 15 mm long (usually about 12 mm) and 4 mm wide. Pinnule margin crenate to senwe. Acroscopic pinnule base expandedand slightly decurrent and basiscopic pinnule base slightly constricted when visible. Midvein prominent but fading away near the very tip of the pinnule. Lateral veins subopposite, weakly catadromic, extending from the midvein at angles from 30" to 40" at regular intervals of 1 mm. Only the bases of the lateral veins usually visible; lateral veins infrequentlyobserved to bifurcate once near the midrib before reaching the margin. Discussion. The one pinna found of this fern is not very well preserved, but does show enough of the salient features of the pinnule morphology and venation to allow assignment to the species Cladophlebis antarctica. Especially diagnostic is the size and linear shape of the pinnules, their crenate to serrate margins and widely spaced lateral veins which bifurcate once near the midvein. During the Mesozoic, Cladophlebis antarctica was widely distributed in southern Gondwana along the Proto-Pacific coastline. It occurs in several other florasfrom the Antarctic Peninsula: the Middle-Late Jurassic Orville Coast flora (Gee 1984),the Late Jurassic or Early Cretaceous Hope Bay flora (Halle 1913, Gee 1987, in press) and the Early Cretaceous Alexander Island flora (Jefferson 1981). In Argentina,it has been found in the Late Triassic flora of the Llantenes Formation (MenCndez 1951), the Early Jurassic flora of the Rio Atuel zone (Herbst 1964),and the Middle-Late Jurassic flora in TaquetrCn (Bonetti 1963,Herbst & Anzotegui 1968). In New Zealand, C. antarctica occurs in the Early Jurassic floras from Mokoia and Matura, and the Late Jurassic flora from Waikato (Arber 1917, Edwards 1934, Guy-Ohlson 1974).

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Stratigraphical range. Cladophlebis antarctica, known only from the Southern Hemisphere, ranges from the Late Triassic to the Early Cretaceous. Geological implications of the floras As mentioned above, the palaeofloras of the English Coast provide one of the few criteria by which the sedimentary rocks may be dated. In the absence of good stratigraphical indicators, such as pollen and spores, marine microfossils, and certain groups of marine invertebrates, the fossil plant assemblages collected from this previously unexplored region must be used for age determination. Although floral diversity is low, the large-scale collecting from both Erehwon Nunatak and Henkle Peak offers a good indication of the floral assemblagespresent in the area at the time. The Glossopteris flora at Erehwon Nunatak suggests a Permian, probably Late Permian, age for the Erehwon beds. This Permian age is of particular geological interest as it indicates that these rocks are significantly older than any other rocks previously known from this part of the province (Rowleyet al. in press). As discussedby Laudon (in press), the Permian age of the Erehwon beds also provides evidence that subduction-related magmatism began in the English Coast area by the late Palaeozoic. The occurrence of Glossopteris also suggests that these beds may be stratigraphicallycorrelatedto the Polarstar Formationof the Ellsworth Mountains. It is likely that theErehwon beds were depositedon or near the Pacific margin of the PolarstarBasin (Laudon in press). The palaeoecology of the flora confirms the petrographicevidence (Laudon in press) which indicates depositionoftheplantremainsinquiet, terrestrialorpossibly paralic environments. The occurrence of Elatocladus planus at Henkle Peak indicates a probable Middle-Late Jurassic age for the sedimentaryrocks.This occurrenceandthat of Cladophlebis antarctica in similar sedimentary rocks at Mount Goodman support the lithological correlation of these outcrops with the Latady Formation widely exposed on the Orville and Lassitercoastsof south-eastemAntarctic Peninsula(Laudon et al. 1983). As at Erehwon Nunatak, palaeoecological evidence supports the petrographic data (Laudon in press) which indicate the Henkle Peak plant remains were deposited in terrestrial or paralic environments. Acknowledgements I am indebted to all the members of the English Coast field party of 1984-85 for their thorough collecting,and especially to Tom Laudon and Pete Rowley, in addition to Ted Delevaryas and Martin Sander for their assistance, encouragement,and editorial suggestions. Thanks should also go to reviewers



Kathleen Pigg and Greg Retallack for their helpful comments, to Urs Gerber for his help with the photographic work, and to Martin Sander for his help in drafting the figures. This research was carried out partly at the Department of Botany, University of Texas at Austin (USA) and partly at the ETHZurich (Switzerland) whose palynological facilities were used and appreciated.

References ANDERSON, J.M. & ANDERSON, H.M. 1985. Palaeoflora of southern Africa: prodromus ofSouth Africa megafloras-Devonian t o b w e r Cretaceous. Rotterdam: A.A. Balkema, 423 pp. ARBER,E.A.N. 1917. The earlier Mesozoic floras of New Zealand. New Zealand Geological Survey, Palaeontological Bulletin, No. 6, 1-80, ARCHANGELSKY, S. 1970. Fundamenios de paleobotanica. La Plata, Argentina: Universidad Nacional de La Plata. Sene Tknica y Didactica No. 1 1 , 3 4 7 ~ ~ . S. 1986. Late Paleozoic fossil plant assemblages of the ARCHANGELSKY, southern hemisphere. In BROADHEAD, T.W., ed. Landpiants: notesfora short course. University of Tennessee, Department of Geological Sciences, Studies in Geology, 15, 128-142. ARCHANGELSKY, S. & ARRONDO, O.G. 1969. The Permian taphofloras of Argentina with some considerations about the presence of ‘northern’ elements and their possible significance. In Gondwana stratigraphy. International Union of Geological Sciences Symposium, Buenos Aires. Paris: UNESCO, 71-84. ARRONDO, O.G. 1972. Estudio geologico y paleontologico en la zona de la Estancia La Juanita y alrededores. Prov. de Santa Cruz, Argentina. Revista del Museo & La Plata, Sec. Paleontologia, NS, 7,1-194. BAKSI.S.K. 1968. Fossil plants from Raghavapuram mudstone, west Godavari District, AP, India. Palaeobotunkt, 16,206-21 5. BONEIT,M.I.R. 1963. Flora mesojurisica de la mna de Taquetrin (Catiad6n del Zaino), Chubut. Revista a21 Mweo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’ e lnstituto Nacional de lnvestigacibn de la Ciencias Naturales (Argentma), Ser. Paleontologia, 1 (2). 1-43. BOUREAU, E. 1964. Trait6 de paldobotanique. 3: Sphenophyta, Noeggerathiophyta. Pans: Masson et Cx, Ed, 544 pp. COLLINSON, J.R., VAVRA, C.L. & ZAWISKIE, J.L. In press. Sedimentology of h e Polarstar Formation, Permian, Ellsworth Mountains, Antarctica. I n WEBERS, G.F., CRADDOCK, C. & SPLEITSTOESSER, J.F., edr. Geology and paleontology of the Ellsworth Mountains, Antarctica. [Geological Society of America Memoir.] CRIDLAND, A.A. 1963. AGlossopterir flora from theOhioRange, Antarctica. American Journal of Botany, 50, 186-195. o C ~ N ER. O ,1983. Paleoecolgiade microsecuenciasplantiferasdel G ~ p Rio Genoa, Pkrmico de Chubut, Argentina. Ameghiniana, 20, 111-131. EDWARDS, W.N. 1934. Jurassic plants from New Zealand. Annales and Magazine ofNatura1 History,Ser. 10.13.81-109. FEISTMANTEL, 0. 1879. Upper Gondwana flora of the outliers on the Madras Coast. Memoirs of the Geological Survey of India, Pafueonfologica Indica, Ser. 2,1(4), 191-224. FEISTMANTEL, 0. 1882. The fossil flora of the South Rewah Basin. Mem0ir.y of the Geological Survey of India, Palaeontologica Indica, Ser. 12.4 (1). 1-52. GEE,C.T. 1984. Preliminary studies of a fossll flora from the Orville Coast -eastern Ellsworth Land, Antarctic Peninsula. Antarctic Journal of the United States, 19 (5). 36-37. GEE.C.T. 1987. Reinvestigation of a Jurassidretaceous boundary flora from Hope Bay, Antarctica. XIVInternationalBotanicalCongress, Berlin - A bstracts, 333.

IP address: 116.228.55.217

PLANT MEGAFOSSILS FROM THE ENGLISH COAST GEE,C.T. In press. Revision of the Late JurassicEarly Cretaceousflora from Hope Bay, Antarctica. Palaeontographica. GouLD,R.E.1968. Morphology of EquisetumlateralePhillips, 1829,andE. bryanii sp. nov. from the Mesozoic of south-eastem Queensland. Australian Journal of Botany, 16,153-176. GOULD,R.E. 1975. The succession of Australian pre-Tertiary megafossil flora. Botanical Review, 41,453483. GUY-OHLSON, D. 1974. Paleobotanisk exkursion i Nya Zeelandsjura: Curio Bay - den forstende skogen. Fauna och Flora, 6,271-282. HWE, T.G. 1913. The Mesozoic flora of Graham Land. Wirsenschaftliche Ergebnisse der Schwedischen Slidpolar-Expedition,1901-1903,3 (14). 1-123. HARRIS,T.M. 1961. The Yorkshire Jurassic flora. I . ThallophytaPteridophyta. London: British Museum (Natural History), 212 pp. HFRBST, R. 1964. La flora liisica de la zona del Rio Atuel, Mendoza, Argentina. Revista de la Asociacibn Geolbgica Argentina, 19,108-13 1. HERBsT,R.& ANZOTEGLX, L.M. 1968. Nuevas plantas de la flora del jurisico medio (matildense) de Taquetrh, Prov. de Chubut. Ameghiniana, 5, 183-190. JEFFERSON, T.H. 1981. Palaeobotanical contribdons to the geology of Alexanderlsland, Antarctica. Ph. D thesis. University of Cambridge. 256 pp. [Unpublished.] LACEY,W.S.,DUK,VAND.E.&GORDON-GRAY,K.D. 1975. Fossilplantsfrom the Upper Permian in the Mooi River district of Natal, South Africa. Annals of the Natal M u e m . 22.349420. LAUDON, T.S. In press. Petrology of sedimentary rocks from English Coast, M.R.A., CRAME, J.A. & THOMSON, eastem Ellsworth Land. In THOMSON, J.W., edr. Geological evolution of Antarctica. Cambridge: Cambridge University Press. LAUDON, T.S., LIDKE,D.J., DEEVORYAS,T. & GEE,C.T. 1987. Sedimentary rocks of the English Coast, eastern Ellsworth Land, Antarctica. In MCKENZIE, G., ed. Gondwana Sir: structure, tectonics and geophysics. Washington,DC: American GeophysicalUnion, 183-189. [Geophysical Monograph No. 40.) .AUDON, T.S., THOMSON, M.R.A., WLUIAMS, P.L., MILLIKEN, K.L., ROWLEY, P.D. & BOWS, J.M. 1983. Jurassic Latady Formation, southwestern Antarctic Peninsula. In OLIVER, R.L., JAMES, P.R. & JAGO,J.B., edr. Antarctic earth science. Canberra: Australian Academy of Sciences & Cambridge: Cambridge University Press, 308-314. ~ N E N D EC.A. Z , 1951. La flora mesomjica de la Formaci6n Llantenes (Provinciade Mendoza). Revirta del InstitWoNacional de Investigacion de las Ciencias naturales, y Museo Argentino de Ciencias Naturales ‘Bernardino Rivaaiaria’,Ciencias Bodnicas, 2, 145-261. O’NEILL,J.M. & THOMSON, J.W. 1985. Tertiary mafic volcanic and volcaniclastic rocks of the English Coast, Antarctica. Antarctic Journal of the United States. 20 (5). 36-38. PANT,D.D. & GUITA,K.L. 1968. Cuticular structure of some Indian Lower Part 1. Gondwana species of Glossopteris Brongniart. Palaeonfographica, B, 124,45-81. PANT,D.D.& PANT,R.1987. SomeGlossopterir leaves from IndianTriassic beds. Palaeontogruphica, B, 205, 165-178. PANT, D.D. & SINGH,K.B. 1974. On the stem and attachment of Gangamopteris and Glossopteris leaves. Part 11. Structural features. Palaeontographica, B, 147,42-73. PETRELA, B. & ARRONW, O.G. 1984. La tafofl6rula lihica de la Estancia La Juanita, Provinciade SantaCruz, Argentina. Ameghinam, 21,3541. PLUMSTFAD,E.P. 1958. The habit of growth of Glossopteridae. Transacfions of the Geological Society of South Africa, 61. 81-94. PLUMSTEAD, E.P. 1964. Palaeobotany of Antarctica. In ADIE,R.J. ed. Antarctic geology. Amsterdam: North-Holland Publishing Company, 637-654. PLUMSTEAD. E.P. 1973. The Late Palaeozoic GIossopterisflora. In HALLAM, A., ed. Atlas ojpalaeobiogeography. Amsterdam: Elsevier, 187-205. RETALLACK, G.J. 1977. Reconstructing Triassic vegetation of eastem Australasia: a new approach for the biostratigraphy of Gondwanaland.



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Alcheringa, 1,247-277. RETALLACK, G.J. 1980. Late Carboniferous to Middle Triassic megafossil floras intheSydney Basin. I n H m , C . e t a l . , e d s . AguidetotheSydney Basin, 385-430. [Bulletin of Geological Survey of New South Wales, No. 26.1 RIGBY, J.F. 1969. Permian sphenopsids from Antarctica. United States Geological Survey Professional Paper, No. 613-F. 1-1 1. RIGBYJ.F. & SCHOFS,J.M. 1969. Stratigraphic implications of Antarctic sfrafigraphy,International Union paleobotanical studies. In G o n d w a ~ of Geological Sciences Symposium, Buenos Aires. Paris: UNESCO, 91-106. W.R. 1985. Geologicstudies in the RowLEY,P.D.,KELLoGG, K.S. & VENNUM, English Coast, eastem Ellsworth Land, Antarctica. Antarctic Journal of the United States, 20 (5). 34-36. W.R, LAUWN, T.S., THOMSON, J.W., ROWLEY, P.D., KELLOGG,K.S., VENNUM, O’NEILL,J.M. & LIDKE,D.J. In press. Tectonic setting of the English M.R.A., &ME, Coast, eastern Ellsworth Land, Antarctica. In THOMSON, J.A. & THOMSON, J.W., edr. Geological evolution of Antarctica. Cambridge: Cambridge University Press. SAHNI, B. 1928. Revision of the Indian fossilplants. Part I. Coniferales, (a) impressionsand incrustations. Memoirsofthe GeologicalSurvey oflndia, Palaeontologica Indica, NS, 11, 1-49. SCHOPF, J.M. 1968. Studies in Antarctic paleobotany. Anturctic Journal of the United States, 3 ( 3 , 176-177. 1980. Permian and Triassic floral SCHOPF,J.M. & ASKIN, R.A. biostratigraphic zones of southern landmasses. I n DLCHER,D.L. & TAYLOR, T.N., eds. Biostratigraphy of fossil plants. Stroudsburg, Pennsylvannia: Dowden, Hutchinson & Ross, Inc., 119-152. SEWARD, A.C. 1918. Fossil plants. 4 . Ginkgwles, Coniferales, Gnetales. Cambridge: Cambridge University Press, 543 pp. & SURANGE, K.R. 1977a. Fertile bracts and scales of the SHAUA CHANDRA Glossopteris fructifications from the Lower Gondwana of India. Palaeobotanist, 24, 195-201. SHAILA CHANDRA & SURANGE, K.R. 19776. Some scale leaves and sporangia from the Raniganj Coalfield, India. Palaeobotanist, 24,245-253. SHAUCHANDRA & SURANGE, K.R. 1979. Revision of the Indian species of Glossopterir. Birbal Sahnilnstitute of Palaeobotany, Monograph,No. 2, 291 pp. SHIRLEY, J. 1902. Fossil plants from Duaringa, Ipswich, Dawson River and Standwell. Bulletin. Geological Survey of Queensland, 18, 1-16. SITHOLEY, R.V. 1944. Jurassic plants from the Tabbowa Series in Ceylon. Spolia Zeylanica, 24.4-17. TAYLOR, T.N. 1981. Paleobotany: an introduction to fossil plant biology. New York: McGraw-Hill Book Company, 589 pp. E.L. 1985. Plant fossils from the Ellswoah TAYLOR, T.N. & SHOOT, Mountains. Antarctic Journal of the United States, 19 (5), 4 8 4 9 . THOMAS, B. 1981. The evolution of plants andpowers. New York: St Martin’s Press, 116 pp. TOWNROW, J.A. 19670. Fossil plants from Allan and Carapace nunataks, and from the upper Mill and Shackleton glaciers, Antarctica. New Zealond Journal of Geology and Geophysics, 10,456-473. TOWNROW, J.A. 1967b. On Rirsikia and Mataia podocapaceous conifers from the Lower Mesozoic of southern lands. Papers and Proceedings of the Royal Society of Tasmania, 101. 103-138. TOWNROW, J.A. 1969. Some Lower Mesozoic Podocarpaceae and Araucariaceae. In Gondwanu Stratigraphy, International Union of Geological Sciences Symposium, Buenos Aires. Paris: UNESCO, 159-180. WALKOM. A.B. 1917. Mesozoic floras of Queensland. Part I -concluded. The flora of the Ipswich series. d) Ginkgoales, e) Cycadophyta, 0 Coniferales. Publications of the Geological Survey ojQueensland, No. 259. 1-49. WALKOM, A.B. 1919. Mesozoic floras of Quemsland. Pans 3 and 4. The florasoftheBurrumandStyx River Series. Publicationsoftk Geological Survey ojQueensland, No. 263.1-76.

IP address: 116.228.55.217

C.T. GEE

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WALKOM, A.B. 1921. Mesozoic floras of New South Wales. Part 1. Fossil plants from Cockabutta Montain and Talbragar. Memoirs of the Geological Survey of New South Wales, Palaeontology, 12, 1-21. W m , M.E. 1978. Reproductive structures of the Glossopteridalesin the



plant fossil collection of the Australian Museum. Recorb of the Australian Museum, 31,473-505. WH~TE, M.E. 1981. Revision of the Talbragar fish beds flora (Jurassic) of New South Wales. Records of the Australian Museum, 33,695-721.

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