First Record of the Genus Unionites Wissmann (Bivalvia) in the Boreal Permian of Northeast Russia

Abstract

Abstract: Representatives of the bivalve genus Unionites Wissmann are found in the Upper Permian deposits of Northeast Russia, together with the typical high-Boreal Inoceramus-like bivalves Intomodesma sp. Previously, Unionites had been considered exclusively Triassic–Early Jurassic and were only recently found in the Upper Permian of Italy. The finding of representatives of the genus Unionites in the Boreal Upper Permian indicate increased connections of high-Boreal basins and Tethys Superrealm towards the end of the Permian, which began as early as the Middle and Late Wuchiapingian. A new species U. kobyumensis Biakov is described.