New ‘rauisuchian’ fossil material from the lower Elliot Formation of South Africa
Date
2023
Journal Title
Journal ISSN
Volume Title
Publisher
Evolutionary Studies Institute
Abstract
‘Rauisuchians’ are a grade of paracrocodylomorph archosaurs that evolved a diversity of body plans and played a key role in ecosystems
worldwide throughout the Triassic. They are widely believed to have gone extinct during the end-Triassic mass extinction event
though the fossil record of rauisuchians in the latest Triassic is still poorly known. In this study, we describe new rauisuchian fossil
remains from the lower Elliot Formation of South Africa. Based on comparative anatomical evidence, we assign these specimens to the
pseudosuchian clade Rauisuchidae. The addition of this material to the existing southern African fossil record allows us, along with
some new insights into the taxonomic affinities of previously published material, to identify the presence of at least three distinct taxa of
rauisuchian in the Norian of southern Africa: two of the clade Rauisuchidae; and one of the clade Poposauroidea. These likely filled
the ecological role of apex predators in the Late Triassic of southern Africa. We also provide a revision of the stratigraphic record
of ‘rauisuchians’ from the Elliot Formation and show that the existing record of rauisuchians in southern Africa, though among the
youngest in the world, does not extend beyond the late Norian. Further exploration of the Elliot Formation and other terrestrial deposits
at the Triassic–Jurassic boundary will be needed to assess whether rauisuchians survived until, or even beyond, the end-Triassic mass
extinction event.
Description
Keywords
Rauisuchidae, Late Triassic, Norian, palaeoecology, biostratigraphy, end-Triassic mass extinction, Stormberg Group