Gorynychus

Gorynychus is a genus of therocephalian from the mid-Permian from Kotelnich, Russia. The genus contains two species, G. masyutinae and G. sundyrensis. It was named after the three-headed dragon Zmey Gorynych (Змей Горыныч) from Russian mythology.

Description
G. masyutinae, only known from its holotype, was wolf-sized and appears to have represented the largest predator in the Kotelnich fauna. Like many theriodonts, it had strongly developed and prominent canine teeth.

Paleoecology
The discovery of such a large therocephalian as the apex predator of its environment coupled with the discovery of a smaller gorgonopsid, the smaller and nocturnal Nochnitsa, in the same formation indicates that a faunal turnover was occurring at the time, with gorgonopsians taking over the therocephalians' role as the dominant predators in their environment.