Dinoflagellate cysts (dinocysts) have been studied in the Coniacian-Campanian deposits of the Usa River basin (polar Cis-Urals), where the Canningia macroreticulata, Chatangiella chetiensis, Spinidium spp.- Isabelidinium spp.-Chatangiella verrucosa, and Chatangiella niiga local zones are established. Dinocyst assemblages from the polar Cis-Urals contain characteristic species of the Arctic and Boreal-Atlantic biogeographic realms in approximately equal proportions. The local zones are confidently correlated with dinocyst zones of the Ust'-Enisei and Khatanga areas, where the latter are dated based on inoceramid fauna. The deposits studied are dated and divided into stages and substages. Paleontological characterization of Campanian siliceous sequence considered formerly as "barren of fossils" is presented. The Coniacian, Santonian, and Campanian deposits of the Enisei-Khatanga and polar Cis-Uralss, northwestern Europe, Arctic Canada, and Atlantic coast of the United States are correlated based on their algal floras.
