Paleocene–Lower Eocene paleontological record of the Ulyanovsk-Syzran facial district, Volga-Peri-Caspian region

The stratigraphic subdivisions of the Paleogene included in the updated regional stratigraphic scheme of the Ulyanovsk-Syzran facial district with a wide development of biosiliceous deposits, are described and paleontologically characterized. The biostratigraphic subdivision of the reference sections using diatoms and dinocysts is discussed. The recently recognized stratigraphic units, Smyshlyaevka and Karanino within the Kamyshin (Upper Paleocene) and Proleyka (Lower Eocene) regional stages are described.