NEW DATA ON THE DISTRIBUTION OF THE BIVALVE GENUS FORTIPECTEN IN THE MARUYAMA FORMATION OF SOUTHEASTERN SAKHALIN

Abstract

The shells of the bivalve genus Fortipecten Yabe et Hatai were found in the Lower Unit of the Maruyama Formation of the Makarov District of Southeastern Sakhalin. Earlier the genus was found only in the middle member of the formation (Middle Maruyama), where the Miocene-Pliocene boundary was placed at the level of Fortipecten's appearance. New finds extend the stratigraphic range of the genus within the Makarov Section, where it occurs not only in Pliocene strata but also in Upper Miocene ones. A new species Fortipecten marujamensis sp. nov. is described.