The Most Ancient Finding of the Inoceramus-Like Bivalves Aphanaia in the Lower Sakmarian Deposits of Northern Verkhoyanie, Northeast Asia

The most ancient representative of the Permian Inoceramus-like bivalves, Aphanaia sp., which dominated in later (Middle and Late Permian) benthic communities, is found for the first time in the Lower Sakmarian deposits of Northern Verkhoyanie (Northeast Russia). The age of the finding is confirmed by the presence of zonal brachiopod species Jakutoproductus insignis Abramov et Grigorjeva. Previous most ancient finding of the Inoceramus-like forms in the Northern Hemisphere is dated by the end of the Sakmarian Stage. The early appearance of the Inoceramus-like bivalves in the Permian sections of Northeast Asia is related to their invasion from Gondwanan basins in the beginning of the large Echian (Sakmarian–Artinskian) transgression.