A New Most Ancient Permian Inoceramus-Like Bivalve of the Genus Aphanaia Koninck from Northeastern Asia

摘要

The most ancient representative of Permian Inoceramus-like bivalves, Aphanaia kletzi sp. nov., from the Upper Sakmarian of the Western Verkhoyansk Region (northeastern Asia) is described. It is established for the first time that the first kolymiids appeared in the northeastern Asian basins in the latter half of the Sakmarian rather than at the end of the Artinskian. The age of the record is reliably dated by the ammonoid genera Uraloceras and Neoshumardites.