Biostratigraphy and Paleogeography of the Bazhenovo Formation (Upper Jurassic and Lower Cretaceous) Based on Radiolarians, Nannoplankton and Calcareous Dinocysts

New data on the taxonomic diversity of radiolarians, calcareous dinocysts and nannoplankton associations in the Late Jurassic and Early Cretaceous of the Bazhenovo Formation of Western Siberia are presented. Analysis of the distribution of radiolarians in the Bazhenovo Formation confirms the possibility of its division into five biostratigraphic units. The upper part of the Bazhenovo Formation, according to the calcareous dinocysts, includes five biostratigraphic units at the rank of beds with microfauna. The presence of the genus Parvicingula confirms that the Bazhenov Sea was a marginal marine basin connected with the Paleo-Pacific Ocean.