Biostratigraphy of the upper Neopleistocene in the northeastern European Russia

We revised materials on the biostratigraphy (collared lemming, Dicrostonyx and narrow-headed vole, Microtus gregalis) of the Upper Pleistocene in the northeas- tern Europe. Biostratigraphic method is tested by lithological and palynological data for determining the age of geological bodies. Age biochronological criteria for the evolutional-morphological level of teeth development in collared lemming and narrow-headed vole were suggested. It was found that morph 2 D. gulielmi, as well as high (about 50%) portion of gregaloid morphotype among the first lower molars of M. gregalis is characteristic for the Early Valdai. Lemmings of the morphs 2 and 3 of D. gulielmi lived during the Middle Valdai; morph 3 D. gulielmi and D. ex gr. gulielmi-torquatus - during the Last Glacial Maximum. D. gulielmi morph 3, D. ex gr. gulielmi-torquatus, D. torquatus morphs 1 and 2 are typical for the Late Glacial; morphs 1 and 2 D. torquatus - for the Early Holo- cene, and morph 3 D. torquatus - for the Late Holocene and the Present. Low (less than 25%) portion of gregaloid morphotype of m1 is typical for the Middle- Late Valdai and Recent narrow-headed voles.