Gorgonopsian therapsids (Nochnitsa gen. nov. and Viatkogorgon) from the Permian Kotelnich locality of Russia

The early evolution of gorgonopsians is poorly understood. New material from the Kotelnich locality in Russia expands our knowledge of middle/earliest late Permian gorgonopsians from Laurasia. Two gorgonopsian taxa are recognized from Kotelnich: Viatkogorgon ivakhnenkoi Tatarinov, 1999 and Nochnitsa geminidens gen. et sp. nov. Nochnitsa can be distinguished from all known gorgonopsians by its unique upper postcanine tooth row, composed of pairs of teeth (a small anterior and larger posterior) separated by diastemata. Both Viatkogorgon and Nochnitsa are relatively small gorgonopsians, comparable in size to the South African middle Permian taxon Eriphostoma. Inclusion of Viatkogorgon and Nochnitsa in a phylogenetic analysis of gorgonopsians recovers them in basal positions, with Nochnitsa representing the earliest-diverging gorgonopsian genus. All other sampled gorgonopsians fall into two major subclades: one made up entirely of Russian taxa (Inostrancevia, Pravoslavlevia, Sauroctonus, and Suchogorgon) and the other containing only African gorgonopsians. The high degree of endemism indicated in this analysis for gorgonopsians is remarkable, especially given the extensive intercontinental dispersal inferred for coeval therapsid groups.