bivalves

In the ?Ozerki? sections, in the terrigenous and carbonate rocks, a faunal complex has been determined – unusually diversified and relatively abundant for the right-bank part of the Saratov Region. Examination of the specified groups of fossil invertebrates has allowed to propose variants for biostratigraphic division and correlation of the sections under consideration. The carbonate rocks are supposed to belong to the Turonian-Coniacian and the underlying terrigenouscarbonate rocks are regarded as the Lower Turonian ones. Formation of the ?sponge?

Based on the study of cephalopods and bivalves, the paleontological characteristics of the Ryazanian (lowermost Lower Cretaceous) sections were supplemented in the stratoregion located in the Oka River Basin near Ryazan, Central Russia. The data obtained are important for the analysis of the stratigraphic position in subboreal sections of taxa known in the Arctic, and the subsequent qualitative development of the zonal level of scales for belemnites and buchias of the Jurassic-Cretaceous boundary interval of the Russian Plate.