Palaeont. afr., 25, 87 - 110 (1984) A REVIEW OF THE REPTILE AND AMPHIBIAN ASSEMBLAGES FROM THE STORMBERG OF SOUTHERN AFRICA, WITH SPECIAL EMPHASIS ON THE FOOTPRINTS AND THE AGE OF THE STORMBERG by Paul E. Olsen* and Peter M. Galton** *Yale University, Peabody Museum, Box 6666, 170 Whitney Ave., New Haven, Connecticut, 06511 USA **Biology Department, University of Bridgeport, Bridgeport, Connecticut 06001, USA. ABSTRACT The Molteno, Elliot, and Clarens formations comprise the continental Stormberg Group of the Karoo Basin of South Africa and Lesotho. The Molteno Formation contains a well preserved macro- and microfloral assemblage but apparently no vertebrates; the Elliot and Clarens formations contain abundant vertebrates but virtually no floral remains. The vertebrate taxa represented by skeletal remains are listed and divided into two assemblages - the lower Stormberg (lower Elliot) and upper Stormberg (upper Elliot and Clarens) assem­ blages. The abundant, diagnosable footprint taxa are revised and their names reduced to eight genera. These ichnotaxa also fall into two biostratigraphic zones that parallel the skel­ etal assemblages. Comparison of the faunal assemblages with those of the European type section strongly suggests that the lower Stormberg assemblage is Late Triassic (Carnian­ Norian) in age while the upper Stormberg assemblage is Early Jurassic (Hettangian-Pliens­ bachian) in age. Comparisons with other continental assemblages from other areas suggest that the upper Stormberg (upper Elliot and Clarens formations) assemblage broadly corre­ lates with the upper Newark Supergroup of eastern North America, the Glen Canyon of the southwestern United States, and the lower Lufeng Series of China- all thought to be of Early Jurassic age on the basis of floral and/or radiometric evidence. Based on these co­ rrelations, previously published paleobiogeographic maps are revised; these show a shift from Late Triassic floral and faunal provinciality to Early Jurassic homogeneity. This shift was synchronous with a widening of the equatorial arid zone. CONTENTS INTRODUCTION ..... . Geological distribution of fossils ..... . SKELETAL ASSEMBLAGES .. Page 88 88 89 Lower Stormberg (lower Elliot) skeletal assemblages . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 Upper Stormberg (upper Elliot and Clarens) skeletal assemblages . . . . . . . . . . . . . . . . . . . . 90 Comparison of the Stormberg skeletal assemblage with assemblages from other areas. . . . . . . 90 Age of Stormberg skeletal assemblages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 FOOTPRINT ASSEMBLAGES OF THE STORMBERG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Lower Stormberg (lower Elliot) footprint assemblage . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Age-significance of the lower Stormberg footprint assemblage . . . . . . . . . . . . . . . . . . . . . . 97 Upper Stormberg (upper Elliot and Clarens) footprint assemblage . . . . . . . . . . . . . . . . . . . 99 Age-significance of the upper Stormberg footprint assemblage . . . . . . . . . . . . . . . . . . . . . 101 IMPLICATIONS OF CORRELATION . _ The Triassic ........ . The Early Jurassic ............ . REFERENCES ..... . ... _ 102 102 104 105 APPENDIX ......................... -..... -. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 MS accepted March 1983 87 88 INTRODUCTION Late Triassic and Early Jurassic terrestrial rep­ tile remains from fluvial, lacustrine, and eolian sediments are found on all continents, but the best known diverse assemblages are from the Stormberg Group of southern Africa (fig. 1). These vertebrate­ bearing beds are virtually barren of other types of fossils such as marine invertebrates and megafossil or mi~rofossil plants. As a result, interpretations of the age of these assemblages have been based on comparisons of the vertebrates with those of other areas that preserve continental deposits. The past few years have seen a revision in opinion on the relative ages of terrestrial assemblages from eastern North America, Europe, and China, and this redating directly affects assessments of the age of the Stormberg. Here we: 1) briefly review the Stormberg !;)keletal assemblages; 2) review and revise the Stormberg footprint assemblages; 3) compare these assemblages to faunules from Europe, North America, South America, and China; and 4) use the redating of all of these early Mesozoic assemblages to arrive at new paleobiogeographic distribution maps for the Triassic and Early Jurassic. Our review and revision of the footprints is al­ most completely based on the work of Ellenberger (1970, 1972, 1974). Our review of the skeletal re­ mains is based on the compilations of Haughton (1924), Haughton and Brink (1955), Crompton (1967), Anderson and Anderson (1971), Kermack ( 1974) Kitching (197 7), Anderson and Cruickshank (1978), and Cooper (1981b). It was, of course, Haughton who first gave us a comprehensive look at Stormberg faunules. It is interesting to note that, although new taxa have been discovered and assign­ ments of the age of the assemblages have bounced back and forth between Triassic and Jurassic, the basic Gestalt of the assemblages and the rationale for dating them have not really changed much since Haughton's seminal work of 1924. Geological distribution of fossils The Stormberg Group of the Karoo Basin co­ vers large portions of South Africa and Lesotho. Over much of that area it overlies earlier Triassic Beaufort beds or older rocks and underlies the Dra­ kensberg Volcanics of Jurassic and younger age (fig. 2). Three sedimentary formations make up the I ~-------+- ---~--~------~~~~~~~~~---+~~~--~----~~+-~~--~r-------,1 30 Figure 1 Positions of major areas discussed in text on a map of the positions of the continents during the Early Jurassic (Pliensbachian): A) Karoo Basin, South Africa; B) Middle Zambezi Valley, Zimbabwe; C) Ischigualasto Basin, Argentina; D) Glen Canyon Group, southwestern U.S.A.; E) Newark Supergroup, eastern North America; F) Germanic Basin, West­ ern Europe; G) "Rhaeto-Liassic" fissure fillings, England; and H) Lower Lufeng Series, Yunnan, China. Base map from Smith (1981 ). Stormberg Group; these are from oldest to youngest (Kent and Hugo, 1978) the Molteno, the Elliot (formerly called the Red Beds), and the Clarens (formerly called the Cave Sandstone), with the Drakensberg Volcanics. on top. These four fo.rma­ tions are formally restncted to the Karoo Basin of South Africa and Lesotho (fig. 1 ), but beds appa­ rently equivalent to these occur in many other areas of southern Africa (Haughton, 1924; Cooper, 1980; Kent and Hugo, 1978). Recent stratigraphic and sedimentologic studies suggest that parts of the Molteno, Elliot and Clarens formations in the main Karoo Basin are, in part, time-equivalents (Van Heerden, 1977, 1979; Tur­ ner, 1971; LeRoux, 1971; Beukes, 1971) (fig. 2) .. Consequently, parts of the lower Elliot are time transgressive. All the assemblages we refer to as lower Elliot, however, come from the oldest por­ tions of the lower Elliot (according to Van Heer­ den 1979), and thus comprise the oldest amphibians and reptiles from the Stormberg Group. Because the assemblages from the upper Elliot and Clarens Formations are not separable at the familial level (see Table 1 and below), the lateral time equiva­ lence of the two formations is not so crucial. Here we refer to the Molteno plus the lower Elliot as the lower Stormberg and to the upper Elliot and Cla­ rens formations as the upper Stormberg, following Ellenberger (1970, 1972, 1974). RADIOMETRIC SCALE EASTERN 89 SKELETAL ASSEMBLAGES A compilation of skeletal remains from the Stormberg is given in Table 1 and the correlation which results from comparison of these forms with those from other areas is shown in Figure 2. The amphibians and reptiles fall into two distinct assemblages, with the break between them occur­ ring within the Elliot Formation (Ellenberger, 1970; Cooper, 1981b). We base our correlations of skeletal assemblages from the Stormberg on compa­ risons with assemblages from the Triassic and Jura­ ssic of Europe and comparisons with other verte­ brate assemblages from continental rocks for which there is cross-correlation with Europe either using pollen and spores or radiometric dates from sect­ ions well dated by marine invertebrates. Lower Stormberg (Lower Elliot) skeletal assemblage The basal beds of the Elliot Formation of the Karoo Basin have produced a sparse assemblage of herptiles (Table 1) that allows limited comparisons with other areas. Only the capitosaurid amphibians and plateosaurid prosauropods (Euskelosaurus - Van Heerden, 1979) are definitely shared (on a familial level) with the European section and they indicate a no more refined correlation than a Late EUROPEAN SOUTH SOUTHWEST N A YUNNAN ARGENT INA STANDARD AFRICA U.S.A Newark CHINA A T ~ p ~ s 8' 165 r-- B ~? ~ T ~ DRAK· p ENSBERG GLEN CANYON GROUP Supergroup .....!.!!1_ M ·~87 S ZONE ~ ARE OF ~ ~ EXTRUSIVES Li68 200 1~2 U ELLIOT -------- - 185·194 N N L ELLIOT ~218 c ~ ~c L ~-\?3.!!.. L 235 ? U. LOWER LUFENG L LOWER LUFENG ? . Figure 2 STAGES AALENIAN TOARCIAN PLIENS- BACHIAN SINEMURI AN HETT· ? ANGI AN U LOS l) COLOR ADOS ~ NORIAN ~ L LOS COLOR ADOS ISCHIGI,;- CARNIAN ALASTO LADINIAN ANISIAN Correlation of the Stormberg Group of South Africa with other areas of continental dep~sit_ion and the European Standard Stages. In the three columns marked RADIOM~TRIC S~ALE th_e letters_ are a~bre_vi atwns of ~ta~e name~ a~ follows: B', Bathonian; B, Bajocian; A, Aalenian; T, Toarcian; P, Pliensbachian; S, Sn~emun~n, H, Hettan_gia~ , N, N~nan , C Carnian· L Ladinian; A', Anisian. The numbers in the same columns are the radiomet:Ically _determme stage o~n­ d~ries Th; n~mbers in the columns marked SOUTH AFRICA and EASTERN N .A. are radwm~tnc. ages for: the extrus~ve k ·. h Th 1 m ked EASTERN N A is a composite of all the formatiOns m the different basms roc s m t at sequence. e co umn ar · · 1 d F · f th of the Newark Supergroup. Abbreviations for formations mentioned in text are as fo!lows: P, Port aa ormr:twnSo . e Hartford Basin, Connecticut and Massachusetts, U.S.A.; M, McCoy Broo~ Formatwn of Fundy roup, ova cotla, Can.; L, Lockatong Formation of Newark Basin, New Jersey and Pennsylvama, U.S.A. 90 Triassic age (Hopson, 1980). However, other rep­ tiles found in the lower Elliot and elsewhere have a much more restricted range and are therefore more useful for correlation. The traversodont cynodont 'Scalenodontoides' (Crompton and Ellenberger, 1957;Cooper, 1981b) is apparently present in the Wolfville Formation of the Fundy Group of the Newark Supergroup (Nova Scotia, Canada) (Hopson, this volume; Baird and Olsen, In Press). Traversodont cynodonts are un­ known above beds confidently dated as Carnian. The Wolfville has produced a diverse although scra­ PPY assemblage of undoubted Late Triassic, proba­ bly Carnian age (Carroll, et al., 1972; Baird and Ol­ sen, In Press; Hopson, this volume). There is also a rauisuchid from the lower Elliot (Hopson, pers. comm.) and this group occurs in beds in Europe, North and South America, and China confidently dated as Late Triassic or older. Furthermore, the lower Elliot appears to be in part a red, lateral equivalent of the upper gray beds of the Molteno Formation, the lower part of which has produced plant . assemblages of Carnian age (Anderson and Anderson, 1970; Anderson, 1974; Anderson, 1978). We conclude that the skeletal remains support a Late Triassic (Carnian and/or Norian) age for this deposit. Upper Stormberg (Upper Elliot and Clarens) skeletal assemblage Of the six families of herptiles known from the Clarens, all but the diarthrognathid therapsids are shared with the upper Elliot (see Table 1 ). The few families found exclusively in the upper Elliot are very rare and imply the same age assessment as do those families present in both formations ( eg. mammals and the theropod Syntarsus). Therefore, we conclude that the assemblages of vertebrates from the upper Elliot and Clarens cannot be distin­ guished objectively on a familial level. Unfortuna­ tely, we regard most distinctions on the generic level to be suspect, especially among the tritylo­ dontids and this is why we do not regard the gene­ ric differences between the Clarens and upper Elliot as significant. At this level of resolution, we con­ clude that whatever age is applied to the Clarens must also be applied to the upper Elliot. This asses­ ment does not, of course, preclude a finer division of the upper Stormberg based on genera or species when we have some confidence at those taxonomic levels. The combination of the upper Elliot and Clarens skeletal assemblages constitutes our concept of the upper Stormberg assemblage. In contrast to the lower Stormberg, most of the reptile families from the upper Stormberg are unknown from stra­ ta of undoubted Triassic age; rather, most upper Stormberg families are known from undoubted Jurassic deposits (eg. European Jurassic, Morrison Formation) or from beds the age of which is as un­ certain as is that of the Stormberg. The division of faunal assemblages corresponds to Cooper's ( 1981 b) Plateosaurus Zone (for the lower Elliot) and Massospondylus + Anchisaurus Zone (for the upper Elliot + Clarens). The Forest Sandstone of Zimbabwe has yielded the plateosaurid prosauropod Massospondylus, the small theropod Syntarsus, a protosuchid crocodile, and a small Glevosaurus-like sphenodontid rhyn­ chocephalian (Cooper, 1981b; Gow and Raath, 1977, Raath, 1969). This assemblage cannot be dis­ tinguished from that of the upper Elliot and Clarens formations, and hence is probably of the same age. To the south of these outcrops in the Limpopo Valley, the Samkoto Formation has produced Mas­ sospondylus (Cooper, 1981b) and these beds prob­ ably correlate with the upper Stormberg and the Forest Sandstone, while the underlying Mpandi Formation has produced Euskelosaurus (Melanoro­ saurus) and thus probably correlates with the lower Elliot (Cooper, 1980). Comparison of upper Stormberg skeletal assemblage with assemblages from other areas A principal problem with any attempt to corre­ late early Mesozoic continental rocks with the Eu­ ropean section is that most of the European Early Jurassic section is marine and the few continental beds that are interbedded with marine beds have produced very few terrestrial vertebrates or are themselves of questionable age ( eg. the Infralias of France). This lack of information on the composi­ tion of unambiguously Early Jurassic continental assemblages makes it difficult to assess the age­ significance of taxa that range to the top of the European terrestrial Triassic but which do not occur in the overlying marine Early Jurassic. An additional impediment to correlation with the European section is the recent tendency not to recognize the Rhaetian Stage of the Late Triassic (Tozer, 1979; Pearson, 1970; Hallam, 1981, 1982) because that stage cannot be distinguished from the Norian on the basis of marine invertebrates in the type area or elsewhere. On the other hand, palynologists do recognize a distinct "Rhaetic" po­ llen and spore assemblage (Schuurman, 1979); "Rhaetian"' microflorules have been recognized on an intercontinental scale, especially in continental rocks (Comet~ 1977). It seems likely that most pa­ lynologically dated continental vertebrate assem­ blages, previously termed Rhaetian, should be termed Late Norian. In contrast, however, most of the European "Rhaetian" megafossil plant florules have proved to be Earliest Jurassic (Achilles, 1981) on the basis of pollen and spores. On top of this confusion, the status of European "Rhaeto-Liassic" bone-bed assemblages and "Rhaetic" continental vertebrate assemblages is very uncertain; some may be Norian, others Jurassic (Clemens, 1980). Thus, the German Stubensandstein and Knollenmergel provide the only secure comparative base for the European Norian and hence the latest Late Triassic. We therefore follow Tozer (1979) and Pearson (1970) and recognize the Norian as the youngest 91 Table 1 LIST OF THE STORMBERG TETRAPOD TAXA KNOWN FROM SKELETAL REMAINS: CLASS, ORDER, FAMILY, GENUS AND SPECIES ARE GIVEN. SOURCE IS ANDERSON AND ANDERSON (1970), EXCEPT AS NOTED. UPPER STORMBERG Clarens Formation Reptilia Crocodiliomorpha Protosuchidae ( Stegomosuchidae) Notochampsa istedana Pedeticosauridae (Sphenosuchidae) Pedeticosaurus leviseuri Saurischia Anchisauridae (includes Plateosauridae) Massospondylus carinatus (see Cooper, 1981) Ornithischia Heterodon tosauridae Geranosaurus atavus Therapsida Tri ty lodon tidae Tritylodontoideus maximus Diarthrogna thidae Diarthrognathus broomi Upper Elliot Formation Reptilia Chelonia ?Proganochelyidae (Kitching, pers. comm., 1980) Crocodiliomorpha Protosuchidae (Stegomosuchidae) Ery throchampsa longipes Orthosuchus stormbergi Pedeticosauridae Sphenosuchus acutus Saurischia Anchisauridae (includes Plateosauridae) (see Galton and Cluver, 1976) Massospondylus carinatus (see Cooper, 1981a) Podokesauridae \Procompsognathidae) Syntarsus sp. (Raath, 1980) Ornithischia Fabrosauridae (see Galton, 1978) Fabrosaurus australis Lesothosaurus .diagnosticus Heterodon tosauridae (see Hopson, 19 7 5) Heterodontosaurus tucki Lycorhinus angustidens Abrictosaurus consors (Thulborn, 1974) Lanasaurus scalpridens ( Gow, 19 7 5) Therapsida Tri ty lodon tidae Tritylodon longaevus (Anderson and Cruickshank, 1978) Tri theledon tidae Pachygenelus manus Trithelodon riconoi Mammalia Docodonta Morganucodontidae Ery throtherium parringtoni Megazostrodon rudnerae LOWER STORMBERG Lower Elliot Formation(= "Passage Beds", "upper Molteno") Amphibia Temnospondyli Capi tosauridae Genus and Species incertae sedis (Ellenberger, 1970; Hopson, this volume) Reptilia Thecodontia . Rauisuchidae (Prestosuchidae) Saurischia Genus and Species incertae sedis (Hopson, this volume); also Seeley, 1894, fig. 1 for large maxilla that was incor­ rectly referred to prosauropod Euskelosaurus -Galton, in prep.) Anchisauridae (includes Plateosauridae and Plateosauravidae) Euskelosaurus browni Melanorosauridae Melanorosaurus readi (Haughton 1924) (regarded as valid taxon following Van Heerden, 1977, and Cooper, 1980 not junior synonym of Euskelosaurus as stated by Van Heerden, 1979 -Galton, in prep.) ?New Genus and Species (Van Heerden, In Press) Therapsida Traversodontidae Scalenodontoides macrodontes (Hopson, this volume) BP-G 92 stage of the Triassic. The dinosaurian families Anchisauridae (inclu­ ding Plateosauridae, Galton, 19 71) and Procomp­ sognathidae (i.e. small theropods = coelurosaurs), and possibly the turtle family Proganochelyidae (Kitching, pers. comm.) occur in the upper Storm­ berg and in the Norian of Germany, but no genera are shared. A newly discovered faunule from conti­ nental rocks in the northeastern France shares mor­ ganucodontid mammals with the upper Stormberg assemblage, but the age of this faunule has not been determined with confidence (Sigogneau­ Russell, 1978; Clemens, 1980). The "Rhaeto­ Liassic" bone beds of Europe lie between fully ma­ rine Early Jurassic rocks and continental Late Trias­ sic rocks. Their exact correlation with the Euro­ pean standard stages is not precisely known, but they could be as old as Norian or Hettangian, and all the occurrences need not be of the same age (Clemens, 1980). The families Tritylodontidae and Morganucodontidae occur in the upper Stormberg and in at least some of the "Rhaeto-Liassic" bone beds; the genus Tritylodon is originally from the "Rhaeto-Liassic" bonebeds at Wurttemberg (Lydek­ ker, 1887); Clemens, 1980) and also occurs in the upper Stormberg (upper Elliot) (Clemens et al., 1979). Fortunately, there are early Mesozoic terrestri­ al vertebrates preserved in fissure fillings in Great Britain associated with marine fossils and/or floral remains that permit direct correlation with near­ by marine rocks of unquestioned age. Some of these small pockets share a large proportion of their taxa with the upper Stormberg assemblage. Robinson ( 19 57) divided the fissure assemblages into two age groups. The older set produces the peculiar gliding reptile Kuehneosaurus and other lepidosaurs. Kuehneosaurus is very similar to Icaro­ saurus from the Lockatong Formation of the New­ ark Basin portion of the Newark Supergroup (Col­ bert, 1966, 1970). The age of the Lockatong is Late Carnian (Comet, 1977; Olsen, 1980a) and on that basis the older set of fissure fills could be of the same age. The younger set of fissure fillings contains mammal (kuehneotheriid, haramiyid, and morgc:nucodontid), tritylodontid, and lepidosaur ~atenal as well as abundant floral remains belong­ Ing to the Himeriella ( = Cheirolepis) association. Pacey (1978, cited in Kermack, Mussett, and Rig­ ney, 1981) has restudied this association and con­ c~uded !hat . it is Early Jurassic (probably early Sinemunan) In age. Morganucodontids, and tritylo­ dontids (Kermack, 1956) occur in both the Jurassic fissure fillings and the upper Stormberg assemblage. At this writing, it is important to stress that there are no records of morganucodontid mammals or tritylodontids in unambiguously Late Triassic rocks. In fact, many morganucodontid and tritylo­ dontid remains from Europe come from rocks of ~ndoubted Jurassic age (such as the Middle Juras­ Sic -Freeman, 1976a, 1976b; Charlesworth 1838· Simpson, 1928) or are correlated with the J'urassi~ on the basis of marine (Oligokyphus : Kuhne, 1956) or floral evidence (Morganucodon : Kermack, Mus­ set, Rigney, 1981). Other deposits that have produced skeletal taxa shared with the upper Stormberg assemblage and have yielded independent age-correlative data in­ clude the Newark Supergroup of eastern North America (Olsen and Galton, 1977), the Glen Canyon Group of the southwestern United States, and the Lower Lufeng Series of China. The younger beds of the Newark Supergroup share a series of taxa with the upper Stormberg assemblage. On a familial level, the Portland Formation of the Hartford Ba­ sin of Connecticut and Massachusetts shares proto­ suchian crocodiles and anchisaurid prosauropods. These remains are associated with palynoflorules ranging in age from Pliensbachian to Toarcian (Cor­ net, 1977; Olsen, 1980a). K/Ar dates from the ba­ salt flows underlying the Portland Formation range from 194-185 Ma (Masterton, 1979), indicating an Early Jurassic age for the basalts (Olsen, Mc­ Coy and Thomson, 1982) and overlying beds. The McCoy Brook Formation of the Fundy Basin of Novia Scotia, Canada is interbedded with and over­ lies the North Mountain Basalt of Early Jurassic age (Olsen, 19 81). Skeletal remains from the McCoy Brook Formation include an anchisaurid prosauro­ pod dinosaur (cf. Ammosaurus), a small fabrosau­ rid dinosaur, a ·?procompsognathid dinosaur (aff. Syntarsus ), and a protosuchid crocodile (Olsen and Baird, 1982 and In Prep.). These beds almost cer­ tainly correlate with the upper Stormberg. In addi­ tion, this latter assemblage is especially similar to that from the Forest Sandstone of Zimbabwe. All the taxa (on at least the familial level) present in the Forest Sandstone are also found in the McCoy Brook. In addition, the sphenodontid present in the Forest Sandstone is generically (and possibly specifically) indistinguishable from the sphenodon­ tid from the McCoy Brook Formation. Both forms are similar, but not identical, to Glevosaurus from the fissure fills of Great Britain (Robinson, 1957, 1973;Pacey, 1978). The resemblance of the Jurassic part of the Newark to the upper Stormberg is espe­ cially obvious when their footprint assemblages are compared (see below). The Glen Canyon Group of the southwestern United States (Wingate, Moenave, Kayenta, and Navajo formations) shares a growing list of skeletal forms with the upper Stormberg assemblage on a familial level and shares a number of genera as well. On a familial level, the Glen Canyon shares tritylo­ dontids (Lewis, 1958; Kermack, 1982), fabrosaurid omithischian dinosaurs (Colbert, 1981), heterodon­ tosaurid omithischian dinosaurs (Crompton, pers. comm.), prosauropod dinosaurs (Galton, 1976), and protosuchian crocodiles (Smith and Crompton, 1980) with the upper Stormberg. On a generic level, the upper Stormberg and the Glen Canyon share the prosauropod Massospondylus (Crompton, pers. comm. ). The upper Newark Supergroup and the Glen Canyon Group share on a familial level sphenodontid rhynchocephalians, protosuchid crocodiles, plateosaurid prosauropod dinosaurs, fa­ brosa~rid dinosaurs, and procompsognathid thero­ pod dmosaurs (Olsen, 1980a; Olsen and Baird, In Press) and they share on a generic level the prosau­ ropod Ammosaurus (Galtort, 1976). It should also be noted that the skull of Ammosaurus Marsh 1889 is very inadequately known (Galton, 1976) and the skull of the American species of Massos­ pondylus Owen 1854 lacks any postcranial skele­ ton. Consequently, it is possible, but by no means certain, that all the material described as Ammosau­ rus major (Marsh) should be referred to Massospon­ dylus. The Glen Canyon Group has produced a pol­ len and spore assemblage from near its base (Moe­ nave Formation) of Early Jurassic age (Sineumurian or Pliensbachian) (Comet quoted in Olsen and Gal­ ton, 1977). In addition, the Glen Canyon Group shares the tritylodontid Oligokyphus, kuehneother­ iid and haramiyid mammals, and ?protosuchid cro­ codiles with the English Jurassic fissure fills ( Cromp­ ton, Jenkins, and Sues, pers. comm.). A tritylodon­ tid recently described from the Glen Canyon Gro­ up, Kayentatherium Kermack 1982, is related to Tritylodon from the Stormberg. The presence of a Tritylodon-like tritylodontid in the Kayenta For­ mation of the Glen Canyon Group has been known for two decades and has been used as evidence by Lewis, Irwin, and Wilson (1961) to conclude that the age of the Glen Canyon Group is Late Triassic because the Stormberg was considered "typical" Late Triassic. Kermack (1982) argues, however, that while at least one Glen Canyon tritylodontid (Kayentatherium) is related to Tritylodon, it actual­ ly suggests an Early to Middle Jurassic age for at least the Kayenta Formation of the Glen Canyon Group (Kermack, 1982). The Lower Lufeng Series of China produces vertebrates very similar to those of the Upper Stormberg. On a familial level, morganucodontid mammals, tritylodontids, plateosaurid prosauro­ pod dinosaurs, fabrosaurid and heterodontosaurid omithischian dinosaurs (Young, 1982), protosuch­ ian crocodiles, and sphenosuchid crocodiliomorphs are shared with the upper Stormberg assemblage (Young, 1951, 1982; Simmons, 1965). On a gene­ ric level, the Lufeng shares Morganucodon with the English fissure fills (Clemens, 19 79). Floral evi­ dence strongly suggests that the lower Lufeng, too, is Early Jurassic in age (Cui, 1976; Sigog­ neau-Russell and Sun, 1981). The only other deposit producing a skeletal assemblage resembling that of the upper Storm­ berg is the Los Colorados Formation of Argen­ tina. It shares plateosaurid prosauropod dino- saurs, protosuchid crocodiles, sphenosuchid croco­ diliomorphs, and tritylodontids on a familial level with the upper Stormberg (Bonaparte, 1971, 1978, 1980, 1981a,b), and in addition the skull of the plateosaurid Coloradia brevis Bonaparte (1981b) is very similar to that of Massospondylus. It also shares stagonolepid, rauisuchid, and omithosuchid thecodonts and plateosaurid prosauropods on the familial level with undoubted Late Triassic beds (Bonaparte, 1978), but the material described as Plateosaurus sp. by Casamiquela ( 1980) is referable to Coloradia. Finally the Los Colorados shares "melanorosaurid" (sensu Van Heerden, 1979, In Press) and plateosaurid prosauropods (Euskelosau­ rus f:om the Elliot [Van Heerden, 19791), and raui­ suchid thecodonts with the lower Elliot. Unfortu- 93 nately, no other forms of age-correlative data have been discovered in the Los Colorados so the assem­ blage is of no real help in dating the Stormberg. The incompleteness of terrestrial vertebrate assemblages from the early Mesozoic of Europe tends to force us to correlate assemblages from other areas with either the Camo-Norian (which is fairly well known in Europe) or the Early Jurassic (which is so very poorly known in Europe). The upper Los Colorados assemblage could, in fact be transitional between "typical" Late Triassic assem­ blages, such as that from the Chinle Formation of the southwestern United States, and what are thought to be Early Jurassic assemblages on the ba­ sis of independent data, such as the upper Newark Supergroup. Without pollen and spores .. megafossil plants, marine invertebrates, or radiometric dates, it is impossible to decide whether the Los Colora­ des assemblage is: 1) of latest Triassic age and the oldest to have several reptile groups otherwise "ty­ pical" of the Early Jurassic; 2) of Early Jurassic age, with the last of the rauisuchid, omithosuchid, and stagonolepid thecodonts surviving; 3) of inter­ mediate age between other known assemblages; or 4) of late Triassic age and indicating that all the other Early Jurassic assemblages discussed above are really Triassic. Our opinion, based on the pre­ ponderance of vertebrates "typical" of well dated Triassic deposits elsewhere, is that the Los Colora­ des is latest Norian (latest Triassic) in age and does contain a true transitional faunule. However, more precise stratigraphical informa­ tion is needed to ensure that this transitional nat­ ure is not the result of mixing finds from different levels because Bonaparte (1978:220) notes that the fauna comes from the top 3OOm. Age of the Stormberg skeletal assemblage On the basis of direct correlation with the European section using taxa based on skeletal re­ mains, the upper Stormberg appears to be no older than very latest Triassic and the bulk of the evi­ dence suggests an Early Jurassic age. This conclu­ sion agrees with that of Kermack ( 19 7 4), Olsen and Galton (1977), and Cooper (1981b). The Early Jurassic age of the upper Stormberg is also suppor­ ted by skeletal evidence from other deposits corre­ lated with the European section by floral means. Finally, the Jurassic age of the upper Stormberg is completely consistent with radiometric dates from the interfingering and overlying lower Drakensberg volcanics which cluster around 18 7 Ma (Fitch and Miller, 1971 ). In summary, we agree with Colbert's (1981, p. 56) comment that, "To place this horizon [the Kayenta Formation] within the Jurassic, it will be necessary to reassign to the Jurassic such formations as the Red Beds and Cave Sandstone in South Africa and the Lufeng Formation in China ... ,., . FOOTPRINT ASSEMBLAGES OF THE STORMBERG The reptilian footprints from the Stormberg re- 94 mained essentially unstudied until the publication of Ellenberger's works. In his most extensive con­ tributions, Ellenberger (1970, 1972, 1974) descri­ bed some 174 new species and 69 new genera of footprints. While we have not had the opportunity to examine the material first-hand, Ellenberger's figures are explicit and, as we will show below, are directly comparable to material from elsewhere. We also feel that Ellenberger's differentiation of the track-bearing horizons of the Stormberg Group into two broad faunal zones reflects a real faunal change through time that is equivalent to the break seen in skeletal remains, and equivalent to the fau­ nal transition seen at the end of the Triassic else­ where. A comparison of figures of Stormberg footprin­ ts known from the Newark Supergroup of eastern , North America (Olsen, 1980a, 1980b) reveals a profound similarity between the upper Stormberg assemblage (Zone B of Ellenberger, 1970) and that of the upper Newark (Zone 3 of Olsen and Galton, 1977). Earlier published works on Newark foot­ prints (eg. Hitchcock, 1848; Deane, 1861; Lull, 1915, 1953) are badly in need of taxonomic, mor­ phologic, and stratigraphic revision; close resem­ blance between the Newark and Stormberg foot­ print assemblages has only become apparent as new material has been found and the older material re­ vised. After careful comparison of Ellenberger's figures with material at our disposal, we conclude that most of the forms described from the Storm­ berg are either congeneric with Newark forms or are indeterminate (figs. 3-5; the valid Stormberg taxa and their synonymies are listed in the Appen­ dix). Of the 24 genera described from the lower Stormberg assemblage (lower Elliot, zone A) by Ellenberger (1972), 15 appear to us to be founded on indeterminate material, seven are congeneric with European forms also found in the Newark (fig. 3), and one very similar to a form found in the Glen Canyon Group of the southwestern United States might be valid. This leaves Pentasauropus as the only definitely valid endemic genus (fig. 3) in the lower Stormberg. Of the 46 genera founded on upper Elliot and Clarens material (Zone B of Ellen­ berger, 1970), 26 appear to be based on indetermi­ nate material, 19 are congeneric with Newark forms, and one (Episcopopus) is distinct but possi­ bly indeterminate. Ellenberger et al. ( 196 7) and Ellenberger (1970) have already made comparisons of Stormberg tracks with tracks from the European early Mesozoic and we agree with the essentials of their correlations. Unfortunately, neither the diver­ sity nor the quality of the European Late Triassic and Early Jurassic tracks compares with those from either the Newark or the Stormberg. The criteria on which we base our assessments of the Stormberg tracks are four; these are listed below along with an explanation of each: f. Tracks are distinct from Trackmakers The first criterion reflects the dichotomy be- tween the trackmaker and its artifact, the track. It is based on Baird's (1957) maxim that "a footprint is not the natural mold of a morphological structure but is, instead, the record of that structure in dyna­ mic contact with a plastic substrate." The trackma­ ker had an existence as an organism belonging.to a population with properties we would use to define species of higher categories. The track is a shadow of the form of the organism, viewed in the dim light of behaviour, substrate nature, and diagenesis. The track never had most of the properties of an organism. Without the body-fossil dead in its tracks we can at best imagine the Platonic ideal of which the tracks are shadows - i.e., the foot. Tracks are best grouped objectively, therefore, by their shape. The dichotomy between the track and track­ maker is reflected by the fact that, although we use a Linnean-style system for the tracks. the system is separate from that used for organisms; the meaning of taxonomic categories at lower levels is very diffe­ rent in ichnology and osteological zoology. This is reflected by the exclusion of ichnofossils from con­ sideration by the International Commission on Zoological Nomenclature (ICZN, 1964). We refer to the components of the binomen as the ichnoge­ nus and ichnospecies to differentiate them from biological taxa; ichnogenera and ichnospecies pro­ bably do not correspond to zoological genera and species, respectively (Baird, 1980). In most cases an ichnogenus probably corresponds to the primi­ tive state for foot structure in an entire group. For example, the ichnogenus Grallator could have been made by any of the conservative members of the suborder Theropoda from any part of the Mesozoic. The ichnogenus Anomoepus could have been made by cursorial members of the families Fabro­ sauridae, Hypsilophodontidae, some Iguanodon­ tidae, Psittacosauridae, and some Leptoceratop­ sidae. Nonetheless the stratigraphic distribution of footprint taxa reflects the distribution of some taxonomic categories of organisms (although we may not know what categories they are) and in that way serve as a parallel biostratigraphic system such as Ellenberger has produced for the Storm­ berg and upon which we are elaborating. II. Determinate tracks show Trackmaker morpho­ logy. Our second criterion follows from the first and reflects the unfortunate fact that most footprints are very poor records of foot structure. Those that reveal little of trackmaker's morphology should not, in our view, be formally named. Operationally, the recognition of tracks that deserve names rests on the presence of pads or some unique feature, such as the five short subequal toes of Pentasauro­ pus (fig. 3). We have judged many of Ellenberger's ichnotaxa indeterminate because the tracks show too little structure of the trackmaker and too much of the condition of the substrate or of the animal's movement. This is despite the tautology - used all too often as a justification for naming bad tracks - that any individual track can be differen­ tiated from all others by its unique shape. However, this uniqueness has no taxonomic significance if it does not relate to the structure of the organism that produced it. III. Most useful aspects of track morphology re­ flect osteology. Our third criterion is based on the suggestion by Baird (195 7) that the most useful attributes of a track are those that reflect osteological characters of the trackmaker's foot. These features are most likely to allow placement of tracks in categories that parallel (but may not be identical to) osteolo­ gical taxa; they are hence most likely to allow the recognition of ichnotaxa that are useful as: 1) bio­ stratigraphic indicators; and 2) clues to animals that lived in an area but left no bones. IV. Footprints in the same "growth series" should be synonymized. Our fourth criterion follows from the first and third by recognizing that vertebrates grow and that the bones of the feet commonly change in shape as their size changes. Shape differences that reflect os­ teological differences are those which are most use­ ful for our purposes. But one category of shape dif­ ferences is not valid for dividing tracks or bones into lower categories: namely those characters that vary continuously with size and that are attributable to, or at least not differentiable from, allometric growth. It makes sense to group all the footprints fitting such a "growth series" in the same taxono­ mic category when the apparently systematic diffe­ rences in shape cannot be distinguished from those due to changes in size during the ontogeny of in­ dividuals of the same species However, some size ranges of a particular ichnotaxon may be restricted stratigraphically and therefore we occasionally use an ichnosubgenus designation to retain the utility of a footprint name (see Grallator, below). Below, we describe and redefine the valid foot­ print taxa from the Stormberg by applying the above criteria to the drawings and photographs given by Ellenberger (1972, 1974). These taxa are listed with their synonymies in the Appendix. Lower Stormberg (lower Elliot) footprint assemblage Ichnofamily Chirotheriidae Abel 1935 Ichnogenus Brachychirotherium Beurlen 1950 Brachychirotherium spp. Discussion: The most abundant recognizable tracks from 95 the lower Stormberg appear to be members of the ichnogenus Brachychirotherium Beurlen 1950 (Haubold, 1971) (Brachychirotherian group of Bai­ rd, 1957) (fig. 3). Brachychirotherium is character­ ized by a five-toed pes impression in which digit V is reduced to an oval pad posterolateral to digit IV. From longest to shortest, the digits of the pes are III, IV, II, I, V. The five-toed manus points more or less anteriorly and has digits of subequallength. The relatively primitive structure of the pes and manus suggest that Brachychirotherium was pro­ duced by a large thecodont, perhaps a rauisuchid (Padian and Olsen, In Prep). Given this assignment it is difficult to imagine how advanced bipedal thecodont (rauisuchids or stagonolepids with a reduced digit V) tracks could be distinguished from the tracks of other archosaurs with relatively primitive feet such as prosauropods or crocodiliomorphs. Most thecodonts, prosauro­ pods, and crocodiliomorphs have the same phalan­ geal formula and relative pedal proportions. The ankles differ, but these differences would probably not have shown up in the tracks. On this basis, we conclude that bipedal Brachychirotherium-like tracks cannot be assigned definitely to either theco­ donts or prosauropods or crocodiliomorphs. Fur­ ther, definite assignment of bipedal Brachychiro­ therium-like tracks to the ichnogenera Brachychi­ rotherium, Navahopus, or Otozoum cannot be accomplished without some external considera­ tions that lessen the independence of the track in­ formation. The diagnostic criteria of these ichno­ taxa pertain to the manus, not the pes. In track assemblages in which Brachychirotherium tracks are definitely present, we prefer to group bipedal Brachychirotherium-like footprints in ?Brachychi­ rother£um sp., with full knowledge that were ma­ nus impressions present in some of these, we might group the tracks in some other ichnogenus. We thus group uncertain tracks with the more "primi­ tive" ichnotaxa present in the same assemblage and we consider this the conservative practice. Ichnofamily Navahopodidae nov. Ichnogenus Tetrasauropus Ellenberger 1970 Tetrasauropus unguzferus Ellenberger 1970 Discussion: One manus and pes set figured by Ellenberger ( 1972) closely approximates the ichnogenus Nava­ hopus recently described from the Glen Canyon Group of the Southwestern United States by Baird (1980) (fig. 3). Like Navahopus, Tetrasauropus is characterized by a Brachychirothen·um-like pes in which there is no impression (or only a slight im­ pression) of the pad beneath digit V, and a manus with an impression of a very large, falciform, me­ dially directed claw on digit I; the other digits of the manus are much smaller with some lateral di- 96 E F I G I I H e I a b c d e Figure 3 Footprints of the lower Stormberg assemblage compared with forms from the Newark Supergroup, Glen Canyon Group, and Europe. All tracks are drawn as left pes or manus impressions. Stormberg taxa (A,C,E,G,H) are traced and simplified from Ellenberger (1970). Scale 20 em.: A) bipedal Brachychirotherium sp. (Pseudotetrasauropus bipedoida of Ellenberger, 1970, pl. II, fig. 28). B) C) bipedal Brachychirotherium sp. from the Pekin Formation (Middle Carnian) of the Newark Supergroup (North Carolina, U.S.A., Sanford Basin) (specimen not collected). quadrupedal Brachychirotherium sp. (Deuterosauropodopus minor (type A) of Ellenberger, 1970, pl. IV, fig. 51A)). D) Brachychirotherium thuringiacum from Middle Keuper (Norian) of Germany (traced from Frey berg, 1965). E) Tetrasauropus unguiferus (traced from Ellenberger, 1970, pl. III, fig. 36). F) Navahopus falcipollex (traced from Baird, 1980, fig. 12.3, from the Navajo Sandstone (E. Jurassic) of the Glen Canyon Group, Arizona. U.S.A. G) Pentasauropus incredibilis (traced from Ellenberger, 1970, pl. IV, fig. 51A). H) Grallator spp. from the lower Stormberg assemblage: a) Prototrisauropus graciosus of Ellenberger, 1970, pl. I, fig. 14; b) Qemetrisauropus minor of Ellenberger, 1970, pl. I, fig. 7; c) Prototrisauropus rectilineus v. lentus of Ellenberger, 1970, pl. II, fig. 19; d) Qemetrisauropus princeps of Ellenberger, 1970, pl. I, fig. 6; e) Prototrisau­ ropus crassidigitus of Ellenberger, 1970, pl. I, fig. 16). I) Grallator sp~. f:om th: Early J~rassic portion of the Newark Supergroup (apparently identical forms occur in the Late Tr.Iassic (Non_an) portiOn of the Newark as well): a) Grallator sp. from the Towaco Formation of Newark Basm (Hettangian) (redrawn from Olsen 1980b, fig. 20, Ab); b) Grallator sp. from Towaco Formation (redrawn from Olsen, 1980b, fig. 20, Ap); c) type of Eubrontes platypus of Lull 1904, original, A. C. 15/4, fr?m. Turners F_alls Sandstone (~e~tangian), Deerfield Basin, Massachusetts, U.S.A.; d) type of Eubrontes dtvancatus of Hitchcock 1865, ongmal, A.C. 58/1, (E. Jurassic)of Connecticut Valley, Connecticut or Massa­ chusetts, U.S.A.; e) Grallator ~P· from Towaco Formation (Hettangian) of Newark Basin, New Jersey, U.S.A. (redrawn from Olsen, 1980b, fig. 20, A, f). • gits often not impressing. Navahopus might belong in the ichnogenus Tetrasauropus, the latter name having priority; however, we do not formally sug­ gest synonymy because, as Baird (1980, p. 228) notes, " ... better material would be required for any definitive comparison." It is possible that Tetrasauropus is a distorted example of Brachy­ chirotherium. Baird (1980) suggests that the falci­ form claw on the manus and the primtive (for saurischians) structure of the foot indicate that both Navahopus and Tetrasauropus could have been produced by prosauropod dinosaurs, whose bones are found in both deposits. Ichnofamily Grallatoridae Lull, 1953 Ichnogenus Grallator Hitchcock 1858 Grallator spp. Discussion: Three-toed footprints referable to the ichno­ genus Grallator are the second most abundant type of track in the lower Stormberg assemblage (fig. 4, Table 2). Grallator, as currently defined (Baird, 1953; LapparentandMotenat, 1967;0lsen, 1980b), has digits II, III and IV always impressing with di­ git III always the longest, and digits IV and II sub­ equal in length. Occasionally, the tip of the claw on digit I impresses. Except for a single possible resting example from the Newark Supergroup, there is never a manus impression. The ichnogenera GratLator, Anchzsaunpus, and Eubrontes as illusted by Lull (1953) and by the type specimens, show differences in proportions that probably reflect real differences in the osteo­ logy of the feet of the trackmakers (Olsen, 1980b; Baird, 1953) and the main factor responsible for these differences a~pears to be the relative length of digit III. Olsen ( 1980b) has shown that the rela­ tive length of digit III changes continuously with the size of tracks traditionally referred to these three ichnogenera, and suggested that this change in shape with size forms a continuum similar to what would be expected in an ontogenetic series of a single ichnotaxon. It is therefore reasonable to synonymize the names Eubrontes Hitchcock 1845 (the type (A.C. 45/8) being indeterminate) and Anchisauripus Lull 1904 with Grallator Hitchcock 185 8, because specimens within this series cannot be objectively distinguished on a generic level. We suggest using subichnogenus designations to denote tracks in the three broad size categories as represen­ ted by the three original generic names. For exam­ ple, large tracks fitting the same allometric curve as Grallator (only larger) are more usefully termed Grallator (Eubrontes) sp. than Grallator sp. alone. Thus, although Grallator spp. are distributed thro­ ugh the entire Newark Supergroup of eastern North American, Grallator (Eubrontes) spp. appear only in the latest Triassic and become abundant only in the Jurassic (Olsen, 1980a). Only Grallator (Gralla- 97 tor) spp. are present in the lower Stormberg assem­ blage. As noted by Heilmann (1927), Lull (1904 ), Schmidt (1959), Peabody (1948), and Baird ( 1953 ), tracks traditionally referred to Grallator were almost certainly made by small theropod dinosaurs and according to Lull (1953) Eubrontes was produced by large theropod dinosaurs. On the other hand, despite the obvious structural inter­ mediacy between Grallator and Eubrontes, Anchi­ sauripus tracks· were interpreted by Lull (1904) as having been produced by prosauropod dinosaurs, such as Anchisaunpus and Ammosaurus from the Connecticut Valley (hence Lull's epithet Anchi­ sauripus). Recently, Baird (1980) has convincing­ ly demonstrated that prosauropods could never have produced Anchisaunpus-like tracks but that these tracks were also made by theropods ( coeluro­ saurs or camosaurs ). The structural continuity among Grallator, Anchisauripus, and Eubrontes suggests to us that Grallator sensu lato could have been made by various taxa of adult theropods of various sizes or by juveniles of one or more larger theropod taxa. This mirrors Ostrom's (1969) ob­ servations on the structural continuity between what are usually called coelurosaurs and camo­ saurs. However, the fact that we recognize only one ichnogenus, Grallator, does not imply that we think these tracks were made by only one dinosaur species, genus, or even family of reptiles. Ichnofamily Pentasauropodidae nov. Ichnogenus Pentasauropus Ellenberger 1970 Pentasauropus maphutsengi Ellenberger 1970 Discussion: Pentasauropus (fig. 3g) is characterized by its large size, very short stride, and subequal manus and pes impressions that are similarly shaped, with manus and pes bearing five subequal toes. No named early Mesozoic tracks approach the configuration of Pentasauropus and despite the fact the tracks themselves are poor, they are unmistakable andre­ present a valid ichnogenus. Tracks that may be re­ ferable to Pentasauropus are found in the Gettys­ burg Shale of the Gettysburg Basin of the Newark Supergroup (Baird, 1957, pers. comm.). These tracks from the Gettysburg Shale are found in association with Brachychirotherium spp. (Baird, pers comm.). The only early Mesozoic rep­ tile group with feet both large enough and with toes short enough to have made Pentasauropus-type tracks is the dicynodontid mammal-like reptiles. Age-significance of the Lower Stormberg footprint assemblage The generally poor quality of the lower Storm­ berg footprint assemblage decreases its age-signifi­ cance, and therefore only limited comparisons are possible with tracks from elsewhere. However, on a 98 broadly defined ichnogeneric level, the lower Stormberg assemblage shares most of its members with assemblages from the Triassic of Europe and portions of the Newark Supergroup that predate the Late Norian (Ellenberger et al., 1967, 1970). Brachychirotherium is unknown outside the Trias­ sic and Tetrasauropus is too poorly known to be of any age-significance. Grallator spp. are universal through the Late Triassic and Early Jurassic. Three­ toed, presumably dinosaurian footprints are very rare in Middle Triassic rocks (Demathieu, 1970). Finally, Pentasauropus may also occur in the Gettysburg Shale of the Newark Supergroup in an assemblage also containing Brachychirotherium; the age of that assemblage is Carnian-Norian, based on palynomorph assemblages (Comet, 1977). In addition, if Pentasauropus was produced by a dicynodont, then it would again indicate a pre­ Jurassic age. In summary, the determinate foot­ prints of the lower Stormberg (i.e. Brachychiro­ therium and Pentasauropus) indicate a Late Trias­ sic, probably pre-late Norian age, an assessment completely in line with the conclusions drawn from the skeletal material. I: D 6b Q ~ w~of A t a 1: ~ ~ ~G W ~Oa B ~ a c d e f \0\ f!)J rl); ~ r~; ~· ~· ~ (. \!}/ a () ': c c:J d c b D b Ftgure 4 Tracks from the upper Stormberg assemblage compared with tracks from the Early Jurassic of the Newark Super­ group. Stormberg tracks traced from Ellenberger (1970 and 1974). A) Grallator spp. from the upper Stormberg (all tracks redrawn as left pes impressions): a) Grallator damane£ of Ellenberger 1970 (pl. VII, fig. 127); b) Moyen£sauropus palmipes of Ellenberger 1970 (pl. VIII, fig. 68C); c) Otouphepus palustr£s of Ellenberger 1970 (pl. VII, fig. 94); d) Neotrisauropus lambereshei of Ellenberger 1970 (pl. VII, fig. 104b); e) Ka£notrisauropus morij£ens£s of Ellenberger 1970 (pl. VII, fig. 125A); f) Ka£notr£­ sauropus moshoeshoei of Ellenberger 1970 (pl. VII, fig. 124B). B) Grallator spp. from the upper Newark Supergroup (Early Jurassic)(all drawn as left pes impressions): a) type of Grallator cursorius of Hitchcock 1858 from the Portland Formation (Sineumurian - Toarcian) of the Hartford Basin, Massachusetts U.S.A. (original, A.C. 4/1); b) type of Anchisaur£pus h£tchcocki of Lull 1904 from the Turners Falls Sandstone (Hettangian) of the Deerfield Basin, Massachusetts, U.S.A. (original, A.C. 56/1); c) type of "Anchisauripus s£llimani" of Lull 1915 (= Brontozoum sillimani of Hitchcock, 1843) from Portland Forma­ tion (Toarcian) of Massachusetts, U.S.A. (original, same specimen as Hitchcock 1841, pl. 21); d) same as fig. 3, I, c of this paper; e) type of Anchisauripus minusculus of Lull 1904 from the Turners Falls Sandstone (Hettan­ gian) of the Deerfield Basin, Massachusetts , U.S.A. (original, A.C. 16/1); f) same as fig. 3,1,d, of this paper. C) Possible examples of Batrachopus spp. from the upper Stormberg (scale as in D and all drawn as right manus-pes sets): a) Plateotetrapodiscus rugosus of Ellenberger 1970 (pl. IX, fig. 81); b) Suchopus bakoenaorum of Ellen­ berger 1974 (pl. Q); c) Molapopentapodiscus pilosus of Ellenberger 1970 (pl. XI, fig. 116); d) Synaptichnium motutongense of Ellenberger 1974 (pl. Q) (mark indicated as digit IV in Ellenberger 1974 is omitted). D) Type specimen of the type species of Batrachopus, Batrachopus deweyi Hitchcock 1843 according to Lull (1904) (original, A.C. 26/6) (drawn as right manus-pes sets): a) characteristic appearance of manus-pes impres­ sions with less than the full complement of toes on the manus showing, and the pad underlying digit V of the pes not impressed; b) composite of all the information on the type slab, showing five toes on the outwardly directed manus and a pad under digit V on the pes. Upper Stormberg (Upper Elliot and Clarens) footprint assemblage The tracks from the upper Stormberg are at once more diverse and better preserved than those from the lower Stormberg. Absent are the brachy­ chirotheriids and Pentasauropus, and in their place are tracks that were probably produced by a variety of dinosaurs and smaller non-dinosaurian forms. Ichnofamily Batrachopodidae Lull 1904 Ichnogenus Batrachopus Hitchcock 1845 ?Batrachopus spp. Discussion: Batrachopus (fig. 4) is the most abundant small, non-dinosaurian track in the late Norian (Rhaetian of Olsen and Galton, 1977) and Jurassic portions of the Newark Supergroup and seems to be repre­ sented in the upper Stormberg assemblage by a few of the ichnotaxa of Ellenberger (1974) (see Ap­ pendix). Unfortunately, as can be seen from Ellen­ berger's figures, the existing upper Stormberg ma­ terial is too poorly preserved for a certain assign­ ment to be made. Batrachopus can be thought of as a Brachychirotherium derivative, differing from the latter group by the reduction in the size and frequ­ ency of impression of the pad underlying digit V and the outward rotation of the five-toed manus impression (Colbert and Baird, 1958). The functio­ nally tetradactyl pes and the outwardly rotated manus are characteristic of crocodiles (Deane, 1861; Baird, 1957; Haubold, 1971; Padian and Ol­ sen, In Press; Schmidt, 1959). Because the majo­ rity of osteological pedal characters seen in croco­ diles are also characteristic of other crocodiliomor­ phs (such as Pedeticosaurus and Hallopus)(Walker, 1968), it is likely that other crocodiliomorphs (such as sphen osuchids) as well as true croco di­ les (such as protosuchids) could have made Batra­ chopus-like tracks. This agrees with Lull's (1904) suggestion that Newark Batrachopus were made by Stegomosuchus, first thought to be a thecodont, but now known to be a protosuchid crocodile (Walker, 1968). In the Newark Supergroup, Batrachopus is often associated with the much larger and rarer Otozoum. Schmidt (1959) assigned Otozoum to the crocodiles, an opinion with which we agree. Otozoum is basically a "scaled up" version of Batrachopus (Baird, pers. comm. ), but in contrast to its diminutive homeomorph, Otozoum rarely has manus impressions. Lull (1953) and Haubold (1971) have suggested that Otozoum was made by prosauropods; this is very unlikely because the manus impression indicates an osteological struc­ ture wholly unlike that of any known prosauropod but like that of crocodiles. ' Ichnofamily Grallatoridae Lull1904 99 Ichnogenus Grallator Hitchcock 1858 Grallator (Grallator) spp., G. (Anchisauripus) spp., G. (Eubrontes) spp. Discussion: The most abundant type of track in the upper Stormberg assemblage, as in the Jurassic part of the Newark Supergroup, is Grallator spp. (fig. 5 ). The variety of Grallator forms in the upper Stormberg assemblage parallels the range seen in the Newark and, because the quality of much of the material is comparably good, we can confidently assign many of the upper Stormberg forms to Newark taxa as shown in our Figure 5. We reinterpret as marks extraneous to the trackways some of what Ellen­ ?erger (1970, 1972, 1974) interprets as extra digits In som~ o.~ .the _tracks we refer to Grallator spp. For~?~ Indistinguishable from Newark ichnospecies trad~tionally called Anchisauripus sillimani, Anchi­ saurzpus. minusculus, and Eubrontes giganteus are present In the upper Stormberg assemblage, and we grouP. these forms in Grallat or spp. (fig. 5). Like the Grallator tracks from the lower Storm­ berg assemblage, the upper Stormberg Grallator were probably produced by a variety of small to large theropod dinosaurs. The only definite thero­ pod skeletal remains found in the Stormberg of the Karoo basin proper are fragments of the small the­ ropod Syntarsus (Raath, 1980), known from much more complete and abundant remains from corre­ lat~ve ~eds in Zimbabwe (Raath, 1969). Despite its ranty In the Stormberg, Syntarsus makes a good match. for ~he abundan~ ~pper Stormberg Grallator (Anchzsaurzpus) sp. This Is the reverse of the situa­ tion seen in the prosauropods of the upper Storm­ berg assemblage: prosauropods are by far the most common dinosaur, but there are no tracks such as Navahopus, assignable to them in the uppe~ Storm­ berg assemblage. Cooper (1981: 797, fig. 89) considered that several of the ichnotaxa of Ellenberger (1970) from the Upper Stormberg fauna were made by the prosauropod Massospondylus but we refer these taxa to Gralla_tor. (Kainotrisauropus mor£jiensis, K. moshoeshoez, Fig. 4A; Neotrisauropus deambu­ lator) or regard them as indeterminate (Megatr£sau­ ro_pus malutz'ensis, Platysauropus spp.) (see Appen­ dix). Ichnofamily Anomoepodidae Lull 1953 Ichnogenus Anomoepus Hitchcock 1848 Anomoepus spp. Discussion: Next to Grallator, tracks unmistakably belong­ ing to the Jurassic Newark genus Anomoepus are the most abundant ichnites in the upper Stormberg assemblage (fig. 5). Anomoepus trackways are most often bipedal, but sitting or resting impressi- 100 A B D ~ em E F ~. · Figure 5 Tracks from the upper Stormberg assemblage, continued: ~I ~ ' 2cm t-------1 20cm .. c-~ c o., a~~C"'~_c~{, .. .. ~ ... · · ·····. - .····· . ........ ~ .. .-- --··· · · · · ·---· ~~· · . •.•.. · 0<~· · r.o~ ~~ G A) Anomoepus sp. from the upper Stormberg (Moyenisauropus natator v. jejunus of Ellenberger 1970 (pl. VI, fig. 64B). B) type specimen of Anomoepus intermedius. Hitchcock 1865 (original, A.C. 48/1). C and D) Ameghinichnus sp. from the upper Stormberg assemblage (C, Aristopentapodiscus formosus of Ellenberg­ er, 1970, (pl. X, fig. 85A): D, Eopentapodiscus mirabilis v. medius of Ellenberger, 1970 (redrawn reversed from pl. IX, fig. 74A).) E) A meghinichnus patagonicus Casmiquela 1964 (left manus-pes set adapted from Bonaparte, 1978 and Casmi­ quela, 1964). F) Ameghinichnus sp., left manus-pes set from the Towaco Formation (Hettangian) of the Newark Basin, New Jersey, U.S.A. (from Olsen, 1980c, fig. 20, E). G) Episcopopus ventrosus Ellenberger 1970 from the upper Stormberg (from Ellenberger, 1975, pl. I). ons in which all four feet are impressed, along with the metatarsi and sometimes the rump or belly, are common. Anomoepus tracks are often very detail­ ed and, because of the large amount of information available from the trackways, they cannot be con­ fused with other ichnotaxa. The pes is functionally tridactyl, with digits II, III and IV always impress­ ed: digit I, which is larger than in Grallator, is sometimes impressed for its full length in sitting tracks and the tip of its claw often impresses even in walking tracks. The pes is broad and digits II, III and IV tend to be subequal in length with toes ten­ ding to be broadly splayed - much more so than in Grallator. In sitting or resting tracks there is often the impression of the metatarsus and the pes tends to be slightly less · splayed than in fully walking tracks. The manus impression when present has four or five subequal toes and is sometimes rotated outwards. There are never big claws on the manus impression. The upper Stormberg forms we refer to Anomoepus (Table ·3) not only match the Newark form in details of stance, gait, and anatomy, but also in the basic form of the resting impressions, which are unique among reptile trackways (fig. 5). The five-toed manus with small claws, and the tetradactyl pes with digits II-IV subequal,indicates that small bipedal omithischian dinosaurs were the likely makers of Anomoepus tracks. Among the skeletal forms from the upper Stormberg assem­ blage, the fabrosaurids are the best candidates. The other Stormberg omithischians, the heterodonto­ saurids, can be ruled out because their manus is strongly modified, with elongated fingers that bear large claws (Santa Luca, 1980). Similarly, the ma­ nus of prosauropods, with the huge falciform claw on digit I, and the manus of theropods with their elongated phalanges and large claws, can be ruled out (contra Haubold, 1971). The structure seen in the manus and pes impressions of Anomoepus is very similar to that of the manus and pes in Hypsi­ lophodon, Scelidosaurus, Camptosaurus Tenonto­ saurus, Psittacosaurus, and primitive ceratopsians. This general form may be primitive for omithi­ schians. Ichnofamily Ameghinichnidae Casamiquela 1964 Ichnogenus Ameghinichnus Casamiquela 1964 Ameghinichnus spp. Discussion: Casamiquela ( 1964) named a series of quadru­ pedal five-toed tracks from the Middle Jurassic La Matilde Formation of Argentina Ameghinichnus patagonicus. A number of tracks from the upper Stormberg seem to be referable to that ichnogenus (Ellenberger, 1974) (fig. 5). Ameghinichnus is characterized by a five-toed manus and a five-toed pes which are subequal in size. The toes on both manus and pes impressions are subequal in length. In the type species of Ameghinichnus the manus is slightly smaller than the pes. Either the meta­ carpus and metatarsus are as short as or shorter than the phalanges, or the trackmaker was digiti­ grade (as Casamiquela believed). The pace is about equal to the stride in walking tracks, with the pes overstepping the manus in the type species ( Casa­ miquela, 1964). The type material also includes galloping tracks. A form tentatively referred to Ameghinichnus has recently turned up in the Juras­ sic part of the Newark Supergroup of New Jersey (Olsen, 1980b; In Prep). The five-toed subequal manus and pes of Ameg­ hinichnus, both without an offset digit V, are not in themselves necessarily characteristic of any par­ ticular group. On the other hand, in the early Meso­ zoic and especially by the Early Jurassic, the varie­ ty of animals retaining this sort of foot structure was restricted to the last of the therapsid reptiles and the earliest mammals. The size of the larger of the upper Stormberg Ameghinichnus is greater than that of any known mammal of similar age, but the size of the smaller Stormberg tracks is about right for the largest Early Jurassic mammal, Sinoconodon (Hopson, pers. comm.). On the basis of their size and abundance, we suggest that trity­ lodontids are more likely candidates for the upper Stormberg forms and could have been responsible for the type material as well. Of course, skeletal material of tritylodontids is relatively abundant in the upper Stormberg. Ichnofamily incertae sedis Episcopopus Ellenberger 197 0 Episcopopus ventrosus Ellenberger 1970 Discussion: Sloppy quadrupedal tracks with a pace equal to the stride, a five-toed manus slightly smaller than the five-toed pes and a broad tail drag were named Episcopopus by Ellenberger (fig. 5). Superficially, these tracks resemble Pentasauropus from the low­ er Stormberg but differ in three ways: 1) the pro- 101 minent tail drag; 2) the manus is slightly smaller than the pes; and 3) digits IV and V appear to be longest in the pes (or the foot was rotated medially during implantation). These features are not only different from Pentasauropus (justifying the gene­ ric difference), but also imply that Episcopopus and Pentasauropus were produced by very diffe­ rent animals. While Pentasauropus suggests a dicy­ nodont, Episcopopus suggests a chelonian (as Ellenberger (1974) has pointed out). The chelo­ nian known from the Stormberg is about the right size for Episcopopus. There is at least a superficial similarity between Episcopopus and both the possible turtle tracks from the Upper Jurassic of Cerin, France (Chelo­ nichnium cerinense) and the recent turtle tracks described by Berner, et al. (1982). Unfortunately, none of the tracks, including those of the living turtle, are really good enough to warrant detailed comparison with the equally muddled Episcopopus. Age-significance of the upper Stormberg footprint assemblage In the possession of small to large Grallator spp., small to large Anomoepus spp., ?Batrachopus, and Ameghinichnus, the upper Stormberg assemblages very closely resemble those of the Jurassic portions of the Newark Supergroup. The Jurassic age of the upper Newark is based principally on pollen and spores (Comet, Traverse, and McDonald, 1973; Cornet and Traverse, 1975; Cornet, 1977; and Ol­ sen, McCune, and Thomson, 1982) and on radio­ metric determinations of the interbedded and und­ erlying lava flows (Olsen, McCune and Thomson, 1982). In the Newark, Grallator spp. occur through­ out the Triassic and Jurassic portions, but the lar­ ger forms (G. ( Anchisauripus) minusculus and Grallator (Eubrontes) spp.) occur only in the por­ tion dated by pollen and spores as late Norian or younger (Rhaetian of earlier authors). Batrachopus is also restricted to beds dated as late Norian or younger. The assemblages from the late Norian portion of the Newark are virtually identical to assemblages from the "Rhaeto-Liassic" of France (Lapparent and Montenat, 1967). The only taxon represented by abundant material that distinguishes the early Jurassic of the Newark from the latest Triassic of the Newark or the French "Infraliassic" is Anomoepus (Olsen, 1980a), and this form is also abundant in the upper Stormberg. Despite scores of productive Triassic footprint localities from many Newark basins, Anomoepus has never been found in beds other than those dated by palynologi­ cal or radiometric methods as Early Jurassic. A form described by Baird (1964) as Anomoepus from the Triassic (Carnian) Chinle Formation has proved on re-examination to be Brachychirotherium -Baird, pers. comm. ). Likewise, Ameghinichnus_ although rare, is known only from Jurassic locali­ ties. Therefore, on the basis of the footprints alone, via correlation with the Newark Supergroup, the upper Stormberg assemblage is Early Jurassic in age. 102 IMPLICATIONS OF CORRELATION Because the Stormberg contains two types of sediments usually thought of as palaeoclimatic indi­ cators (coals in the Molteno Formation and dune sands in the Clarens Formation -Haughton, 1924 ), the redating of the Stormberg group has broad pal­ eoclimatic and biogeographic implications. Robin­ son (1971, 1973b) plotted the position of the pal­ eoclimatic indicators on a map of the position of the continents during the Triassic, and this figure has since been widely reproduced and quoted. However, the relative ages of virtually all of the North American and African Late Triassic and Early Jurassic deposits have been revised since 1973, so new maps are needed. Many of the paleo­ climatic indicator deposits that were thought to be Late Triassic are now thought to be Jurassic, and new deposits of Triassic and Jurassic dune sands have been found; therefore, we provide two new maps (figs. 6 and 7), one for the Late Triassic (Car­ nian - early Norian) and one for the Early Jurassic (Hettangian - Pliensbachian). Also plotted on the Triassic map are the positions of localities that have produced certain fossils which show a latitude­ dependent distribution. Biogeographic provinces are apparent in the maps for both the Triassic and Jurassic and these are reviewed below. The Triassic (fig. 6) Between north and south 30° latitude, phyto­ saurs and metoposaurs are abundant in Late Trias­ sic (Camian-Rhaetic) continental reptile assembla- oC cc c ... ic _.··- .. ~--- · .. ····z.····· r-------~r---~--~----~r--+~~~~~~~~--~~------~------~~-~·+---~~------~30 ..... ··: Figure 6 Position of the continents during the Late Triassic {Carnian- Norian) showing the occurrences of climate sensitive rocks {C, coals: D, dune sands; E, evaporites), the phytosaur-metoposaur province {p', phytosaurs and metoposaur~: p, only phytosaurs; o, good reptile assemblages but neither phytosaurs or metoposaurs), and the Gondwana floral provmce (i, Ipswich-Onslow microflora + Dicroidium-dominated macroflora). Positions of most coals and dunes are from Robinson {1973), others from Hubert (1980), Olsen, McCune, and Thomson {1981), Anderson and Anderson (1971), and Haughton (1924);positions of evaporites are from Rona (1982) and Robinson (1973); phytosaur and metoposaur occurrences are from Olsen, McCune and Thomson {1981), Colbert and Gregory {195 7), Colbert and Imbrie (1956), Roy-Chowdhury (1965), Dutuit (1979), Buffetaut and Ingavat {1982), and Westphal {1970). Occurrences without phytosaurs or metoposaurs are from Anderson and Anderso~ {1_9?1), Robinson (1971), and Rozhdestvensky (1973). Distribution of the Ipswich-Onslow microflora and the Dzcrozdzum macroflora from Dolby and Balme {1976), Anderson and Anderson {1971 ), and Kumaran and Maheswari (1980). Base map is from Smith {1981 ). ges. In the early Late Triassic (Carnian), metopo­ saur amphibians are uniformly found in association with the phytosaurs. Phytosaurs and metoposaurs are found in abundance in Carnian age rocks in In­ dia (Roy-Chowdhury, 1965) and Morocco (Dutuit, 197 7, 1979), as well as in continental Europe and eastern and western North America (Colbert and Gregory, 1967; Gregory, 1980; Jacobs and Murry, 1980). In addition, phytosaurs have also recently been found in Thailand (Buffetaut and Ingavat, 1982) and may be present in Malagasy (Westphal, 1970). Continental vertebrates are abundant in a number of South American basins in intervals which appear wholly to overlap the time span in which metoposaurs and phytosaurs lived elsewhere (An­ derson and Anderson, 1971). While thecodonts in general and a variety of other labyrinthodont amphibians are abundant, phytosaurs and metopo­ saurs are absent. Likewise, the Molteno and lower Elliot appear to lack metoposaurs and phytosaurs, but again other thecodonts and labyrinthodonts are present (at least in the lower Elliot). Similar­ ly, the Australian Late Triassic labyrinthodont- 103 producing deposits lack phytosaurs and metopo­ saurs (Anderson and Anderson, 1971). Plotted on a map showing the position of the continents du­ ring the Late Triassic (fig. 6), the range of phyto­ saurs and metoposaurs appears to be restricted to the e~uatorial zone between North 40° and South 30 paleolatitude (see also Buffetaut and Ingavat, 1982). During the Late Triassic, India was south of the Tethys seaway (fig. 6). The pre­ sence of phytosaurs and metoposaurs in India shows that physical isolation by oceans of the southern continents cannot be used as a simple explanation for the absence of these herptiles from southern Africa and South America because they could clearly get to India, one of the most isolated segments of Gondwanaland at that time. It seems most likely that paleolatitude-dependant climatic differences were responsible for this provinciality. The phytosaur-metoposaur biogeographic pro­ vince closely follows (although not exactly) the contemporaneous plant provinces. In the Late Triassic southern hemisphere, south of 3 0° S paleo- c c c Figure 7 Positions of the continents during the Early Jurassic {Pliensbachian} showing the occurrences of "climate-sensitive" rocks {abbreviations as in fig. 6). Occurrences of dune sands from Olsen {1981), Parrish, Parrish, and Ziegler {In Press), Haughton {1924), Cooper {1981b), and Cordani, Kawashita, and Filho {1978). Evaporite positions from Parrish, Parrish, and Ziegler {In Press) and Rona (1982}. Positions of coals from Parrish, Parrish, and Ziegler {In Press). Base map from Smith {1981). 104 latitude, all vertebrate assemblages are associated with Dicroidium-dominated megafossil florules. Only in India are phytosaurs and metoposaurs found with a Dicroidium-dominated megafossil complex (Kumaran and Maheswari, 1980). In all other areas, the phytosaur-metoposaur province is associated with a typical bennetitalean-conifer assemblage. In addition, most of the extent of the southern hemisphere in which phytosaurs and metoposaurs are absent corresponds to the Ipswich­ Onslow-type microfloras (Dolby and Balme, 1976; Truswell, 1980). In India, Onslow-type microflo­ rules have been found in beds contemporaneous with the phytosaur-metoposaur bearing beds (Ku­ maran and Maheswari, 1980) and this parallels their association with Dicroidium. In the northern hemisphere, phytosaurs are absent from deposits north of about 30° N paleolatitude; however, this does not seem to correlate with any definite mega­ or microfloral provinciality (Truswell, 1980). Both in northern and southern paleolatitudes above 30°, coals are relatively common in the Late Triassic, particularly in the Carnian (Anderson and Anderson, 1971; Robinson, 1971, 1973). Contem­ poraneous dune sands are absent. South of 30° nor­ th paleolatitude in the northern hemisphere, there are occurrences of dune sands (Hubert, 1980; Olsen, McCune, and Thomson, 1982) and evapo­ rites (Wheeler and Textoris 1978; Robinson, 1973; Rona, 1982), which make no obvious geographic pattern when plotted on paleogeographic maps. In the eastern North American Newark Supergroup, lacustrine deposits are the dominant sediment types, and these deposits record a complex history of cyclic change (VanHouten, 1969; Olsen, 1980b, In Press). Studies of physical stratigraphy and sedi­ mentology indicate that precipitation governed the level of lakes, some of which were periodically lar­ ger than 8200 km2 and more than 100 m deep (Manspeizer and Olsen__, 1981 ). Deposits formed be­ neath these giant lakes alternate vertically with playa lake and desert soil deposits, indicating pro­ found changes in precipitation with a period of roughly 21 000 years. Pronounced compound cyc­ les with a periodicity of 100 000 and 400 000 years are also present (Olsen, In Press). Viewed in the light of periodically fluctuating climate, the mosaic pattern of climatically sensitive rocks in the equatorial zone makes more sense. The dune sands and coals of the middle paleolatitudes need not have been contemporaneous on a 20 000 to 400 000 year scale but could have been deposited during the same long interval of cyclic climate. The Early Jurassic (fig. 7). As has been recognized for several decades, the strong floral provinciality that characterized the Late Triassic world gave way in the Early Jurassic to a more homogeneous flora dominated in many areas by conifers (particularly the Cheirolepidaceae: Alvin, 1982). This is especially evident in the pre­ sumed pollen of the Cheirolepidaceae, Corollina (Classopollis). Hughes (1973) has shown that in the Late Jurassic the relative abundance of Corollina is greatest in the equatorial region, and it appears that this pattern was first established in the Early Jurassic (Comet, pers. comm.). Going from south to north in the circum-Atlantic rifting region, there is a clear trend from Corollina-dominated ( + 90%) (Cornet, 1977) to non-Corollina-dominated floru­ les (- 10% ) (Pederson and Lund, 1980) with tran­ sitional assemblages occurring around 25 o North paleolatitude. This pattern is reflected in mega­ fossils as well, with conifers strongly dominant in the south and much rarer in the north (Cornet> 1977; Pederson and Lund, 1980). The more north­ em assemblages are also far more diverse. In the southern hemisphere, data are as yet insufficient for a similar trend to be recognized, if it exists. The relative homogeneity of the Early Jurassic world floras appears also in the faunas. Not only are the assemblages from different continents simi­ lar in taxonomic composition, with a series of genera being shared, but diversity is similar with the same taxonomic groups dominating the faunu­ les (true for both the skeletal and track assembla­ ges). We are at loss to explain this homogeneity of the terrestrial fauna, especially because it coincides with the beginnings of the fragmentation of Pangea (Manspeizer and Cousminer, 1978). Climate-sensitive rocks show an interesting dis­ tribution in the early Jurassic, with coals being vir­ tually restricted to the higher paleolatitudes (Par­ rish, et al. In Press) (fig. 7). In marked contrast to the Late Triassic, dune sands are very common in a broad equatorial zone in the Early Jurassic. Dune sands occur over a very large area of the south wes­ tern United States in the Glen Canyon Group, in the Fundy Group of the Newark Supergroup (Ol­ sen, 19 81), and in Sou them Africa ( Clarens For­ mation of the Stormberg Group). Evaporites are abundant in the Early Jurassic, being present throughout the circum-Atlantic rifting zone and t~rough t~e circum-Tethyan region (Rona, 1982). Like dune sands, they ap£>ear restricted to a zone between 40° North and 50 South paleolatitude. The relatively homogeneous world terrestrial fauna that was ushered in at the end of the Late Triassic seems to have been maintained for the next 50-100 million years or so, despite the conti­ nuing fragmentation of Pangea (Galton, 1977). Ol­ sen and Galton (1977) disputed the broadly cited mass extinctions of terrestrial vertebrates that sup­ posedly marked the close of the Triassic. Such mass extinctions clearly did occur in the marine realm at the end of the Triassic (Hallam, 1981) but the change in the vertebrate fauna seems to have been more gradual. In fact, the taxonomic turnover rate is the same around the Triassic-Jurassic boun­ dary as it is for the rest of the Triassic (Olsen, in prep). The apparent change that does characterize the transition into the Jurassic is a much reduced extinction rate in terrestrial vertebrates and perhaps this change is tied somehow to the reduction in regional provinciality. 105 ACKNOWLEDGEMENTS Rachootin, Bruce H. Tiffney, and Laurie Walter for reading the manuscript and suggesting useful improvements. Finally, We thank Donald Baird, Richard Boardman, Bruce we are grateful for access to the Hitchcock collection of Cornet, James Hopson, William D. Masterton, Kevin Padi~n, reptile footprints in the Pratt Museum, Amherst College, Keith S. Thomson, Alfred Traverse, and Karl K. Turek1an Amherst, Massachussetts without which this paper would for stimulating discussions and various assistance during the have been impossible. Work on this project was supported preparation of this manuscript. We also thru:k Donald Baird, by National Science Foundation Grants to Keith S. Thomson Cynthia J. 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