First record of a basal synapsid (‘mammal-like reptile’) in Gondwana

Abstract

Elliotsmithia longiceps is a rare synapsid (`mammal-like reptile9) from the middle part of the Tapinocephalus Assemblage Zone (Beaufort Group; Late Permian) of South Africa that belongs to the basal (`pelycosaur9) clade Varanopseidae. Elliotsmithia is important biogeographically because it is the first discovery of a `pelycosaur9 in the southern Pangaean province of Gondwana and only the second record of a `pelycosaur9 in a fauna that is dominated both numerically and taxonomically by therapsid synapsids. It demonstrates that `pelycosaurs9 were not excluded ecologically by therapsids and restricted to equatorial regions, but spread across the supercontinent of Pangaea with therapsids during the Late Permian. The Pangaean distribution of varanopseids accords well with the worldwide occurrences of several groups of therapsids, pareiasaurs, the gliding diapsid reptile Coelurosauravus and captorhinid reptiles, and supports the hypothesis of cosmopolitan Late Permian tetrapods. With the occurrence of Elliotsmithia in the upper Late Permian of South Africa, the fossil record of Varanopseidae extends from the Late Carboniferous to Late Permian and is the longest of any known lineage of Palaeozoic amniotes.