The Parastratotype of the Urzhumian Stage in the Vyatka-Kazan Region, East-European Platform

New multidisciplinary studies of the Urzhumian parastratotype confirm its reference status for the Vyatka-Kazan region of European Russia. The purely continental Urzhumian represents the upper unit of the Biarmian Series (Middle Permian) of the Geological Time Scale of Russia and is tentatively correlated with the Wordian of the International Chronostratigraphic Chart. The lower part of the parastratotype corresponds to the Sulitsa Formation and consists of lacustrine red-bed continental rocks containing rare conchostracans and fish scales. The upper part of the parastratotype corresponds to the Isheevo Formation and is composed of red-colored alluvial-lacustrine terrigenous and clayey rocks with interbeds of microbial limestones. The clayey rocks often include a large number of paleosols of differing maturity, among which vertisols and calcisols prevail. This part of the section contains a diverse fauna of non-marine ostracodes, bivalves, conchostracans, fishes and tetrapods. The Urzhumian parastratotype includes the non-marine ostracode assemblage of the Palaeodarwinula fragiliformis Biozone, the non-marine bivalve assemblages of the Palaeomutela krotowi, P. wohrmani and P. numerosa Biozones, and the fish assemblage of the Platysomus biarmicus-Kargalichthys efremovi Biozone. This makes it possible to reliably correlate it with the numerous Urzhumian sections of the east of the East European Platform. New localities for fishes, amphibians and reptilians increase its correlation potential.