This new paper suggests the presence of dinosauromorph (cf. Rotodactylus) and turtle-like (cf. Chelonipus) trackmakers from the Lower Triassic of Wyoming.
D. M., and S. D. Lovelace. 2012. Paleoenvironments and paleoecology of a Lower
Triassic invertebrate and vertebrate ichnoassemblage from the Red Peak
Formation (Chugwater Group), central Wyoming. Palaios 27:636-657. doi: 10.2110/palo.2012.p12-011r
Abstract - The
Lower Triassic Red Peak Formation of the Chugwater Group has long been
considered to have an extremely poor paleontological record, although the cause
for the apparent dearth of fossils has yet to be been determined. During the
course of fieldwork in central Wyoming numerous vertebrate and invertebrate
ichnogenera (n ≥ 11) were observed. Vertebrate tracks and trackways
representative of dinosauromorph, archosaur, lepidosaur, and testudinate
trackmakers were found (cf. Rotodactylus,
and cf. Chelonipus
respectively). An invertebrate ichnoassemblage composed of at least 6
ichnogenera consistent with the Scoyenia ichnofacies were also found (e.g., Diplichnites, Lockeia, Fuersichnus communis,
and cf. Scolicia).
The majority of these tracks and traces were found in the upper platy facies
(upper 10–20 m of the Red Peak Formation), which is thought to be no younger
than upper Spathian in age. Sedimentary structures, architectural elements, and
lateral stratigraphic relationships support the interpretation of floodplain,
fluvial, and lacustrine deposition for the upper platy facies in central
Wyoming. The Red Peak Formation vertebrate and invertebrate ichnoassemblages,
along with their associated depositional environments, are consistent with a
fluviolacustrine (continental) setting comparable to those described from Lower
to Middle Triassic strata with a Pangean distribution, including the Moenkopi
Formation in the southwestern United States. This ichnoassemblage provides the
first opportunity to observe paleoecological diversity and associated
paleoenvironments within the Lower Triassic of the Chugwater Group.
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