Early middle Pleistocene mammalian and molluscan assemblages from the Novokhopersk locality (Don River basin, Russia)

The central part of the Russian Plain is famous for its Pleistocene deposits. This paper describes the geological structure and mollusc and small mammal faunas of one of the most important middle Pleistocene localities on the Russian Plain, the Novokhopersk. The new data on molluscs and small mammals place the Novokhopersk fauna directly between the more archaic Veretio and Ilyinka faunas and more advanced Volnaya Vershina and Kuznetsovka faunas. Both mollusc and small mammal faunas from the alluvial deposits that underlie the Donian till belong to the Tiraspolian faunal complex (Biharian faunal stage) and are early middle Pleistocene in age. Among small mammals, this placement is confirmed by the presence of Mimomys voles along with archaic representatives of Terricola and Microtus. The mollusc fauna contains several extinct gastropod species, such as Tanousia krasnenkovi, Borysthenia intermedia, Viviparus diluvianus, and Litoglyphus jahni, which also indicate that the fauna belongs to the Tiraspolian faunal complex. Further, the mollusc fauna indicates moderate climatic conditions and corresponds to the modern boreal fauna. The pollen analysis and small mammal data suggest that during that time broadleaf deciduous forests existed on that territory, with scattered steppe landscapes, which probably occupied the watersheds. When compared to Central and Western European faunas, the Novokhopersk fauna correlates well with the Stranska Skala and Zlaty Kun faunas in the Czech Republic, with the fauna of the Betfia 7 locality in Romania, with the Süssenborn fauna in Germany, with the Cromerian sensu lato fauna in Great Britain and corresponds to MIS 18.