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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This page last updated October 8th, 2001.
