A second varanopseid skull from the Upper Permian of South Africa: implications for Late Permian 'pelycosaur' evolution

Late Permian terrestrial faunas of South Africa and Russia are dominated ta xonomically and ecologically by therapsid synapsids. On the basis of a sing le specimen from the Upper Permian of South Africa, the varanopseid Elliots mithia longiceps is the sole basal synapsid ('pelycosaur') known from Gondw ana. Recent fieldwork in the Upper Permian of South Africa has produced a s econd varanopseid specimen that is referrable to Elliotsmithia. Data from b oth this specimen and the holotype suggest that Elliotsmithia forms a clade with Mycterosaurus from the Lower Permian of North America and Mesenosauru s from the Upper Permian of Eastern Europe. That postulate is supported by the three most parsimonious trees discovered in a new analysis of varanopse id phylogeny. However, the available data cannot resolve the interrelations hips of these three genera. The new phylogenetic results contrast with earl ier work identifying Elliotsmithia as the basal member of a clade that incl udes the North American taxa Aerosaurus, Varanops, and Varanodon. The new t rees reduce the stratigraphic debt required by the latter scenario, and the one with the least stratigraphic debt identifies Elliotsmithia and Mesenos aurus as sister taxa. Two new taxa are erected, Mycterosaurinae and Varanod ontinae, for the two varanopseid subclades.