Inostrancevia. Illustration and photo-reconstruction of the mammal-like reptile Inostrancevia. Inostrancevia is an extinct genus of carnivorous therapsids, containing the largest members of the family Gorgonopsidae, predators characterized by long, saber-tooth-like canines. The various species inhabited northern Russia during the Upper Tatarian (Vyatskian), a Russian regional stage equivalent to the Wuchiapingian stage of the Late Permian period, dating from approximately 260 to 254 million years ago. The species in Inostrancevia were the largest gorgonopsids known: with total body lengths reaching up to 3.5 m and long, narrow skulls up to 60 cm long. They weighed about 250 kg.