Dinocephalian stage in the history of the Permian tetrapod fauna of Eastern Europe

The first tetrapods entered continental communities as consumers of the highest order, forming the subdominant and aquatic tetrapod communities. At the end of the Carboniferous, herbivorous tetrapods appeared in North America and Western Europe; the first (pelycosaurian) dominant tetrapod communities were formed. In the Middle Permian, dominant communities are already known in all continents, where they are formed by Dinocephalian (therapsid) faunas. The history of the Dinocephalian fauna is most completely represented in the fossil record of South Africa and Eastern Europe. In the East European region, it is represented in the Mezen, Golyusherma, Ocher, Isheevo, and Sundyr assemblages, displaying successive stages of phylocoenogenesis of Dinocephalian community. The major features of these stages are considered. In the terminal Middle Permian (Guadalupian), Dinocephalian communities were disintegrated worldwide. In Eastern Europe, this occurred during the Severodvinian ecosystem crisis. The main features of the Severodvinian crisis are discussed.