The first skeletal evidence of a dicynodont from the lower Elliot Formation of South Africa

Kammerer, Christian F.
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Evolutionary Studies Institute
Historical fossil specimens from the lower Elliot Formation are identified as representing a large-bodied dicynodont, the first known from skeletal material in the Late Triassic of South Africa. Although fragmentary, these fossils differ from all other known Triassic dicynodonts and are here described as a new taxon, Pentasaurus goggai gen. et sp. nov. Pentasaurus can be distinguished from other Triassic dicynodonts by a number of mandibular characters, most importantly the well-developed, unusually anteriorly-positioned lateral dentary shelf. Phylogenetic analysis indicates that Pentasaurus is a placeriine stahleckeriid. Placeriines include the latestsurviving dicynodonts but their remains are primarily known from the Northern Hemisphere, with their only previously-known Southern Hemisphere representative being the Middle Triassic Zambian taxon Zambiasaurus. The discovery of a placeriine in the Late Triassic of SouthAfrica supports recent proposals that local climatic conditions, not broad-scale biogeographic patterns, best explain the observed distribution of Triassic tetrapods. The tetrapod fauna of the lower Elliot Formation is highly unusual among Triassic assemblages in combining ‘relictual’ taxa like dicynodonts and gomphodont cynodonts with abundant, diverse sauropodomorph dinosaurs.
Synapsida, Therapsida, Dicynodontia, Triassic, Karoo Basin, biogeography