LATE TRIASSIC - EARLY JURASSIC DINOSAUR ICHNOFAUNAS, EASTERN NORTH AMERICA AND SOUTHERN AFRICA

RAINFORTH, Emma C., LDEO/Columbia Univ., Palisades, NY 10964.

Tetrapod footprints are abundant in Late Triassic - Early Jurassic strata of eastern North America (Newark Supergroup) and Lesotho (Stormberg Group), having enormous potential for biostratigraphic and biogeographic studies. More than 50 Newark ichnotaxa have been described, but current studies have reduced this number by an order of magnitude. When first described, the Stormberg tracks were assigned to new taxa; only one prior attempt has been made to evaluate their taxonomy.

A new examination of the Stormberg material suggests most of these tracks should indeed be referred to Newark taxa, although the details differ from the scheme previously suggested. The Stormberg taxa Moyenisauropus and Kainomoyenisauropus are indistinguishable from Anomoepus (ornithischian track), and Kalasauropus is a small Otozoum (prosauropod track), with only minor morphological differences; all these tracks are restricted to the Early Jurassic. Pseudotetrasauropus differs significantly from Otozoum; this and the other large quadrupedal taxa from the Stormberg Triassic, although poorly preserved, are probably large chirotheres (crurotarsan tracks). Most of the remainder of the tridactyl Stormberg taxa can be referred to Grallator, Anchisauripus and Eubrontes (theropod tracks). The largest of these (Eubrontes) are restricted to the Early Jurassic, while the smaller forms occur throughout the Late Triassic - Early Jurassic. Although detailed morphology is lacking, the "birdlike" Stormberg Triassic (and Early Jurassic, SW USA) taxon Trisauropodiscus is more similar to Anomoepus than it is to grallatorids, and is probably an ornithischian track. The Newark Triassic ornithischian ichnotaxon Atreipus does not appear to be present in the Stormberg. The overall succession of footprint faunas is very similar across the two regions, with a reduction in non-dinosaurian ichnotaxa at the Triassic-Jurassic boundary, and diversification of dinosaurian ichnotaxa in the Early Jurassic. An important difference is the lack of prosauropods in the north American Triassic.
 

Journal of Vertebrate Paleontology vol. 21, Supplement to no. 3, p. 91A.
 



 
 
 
 

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