Holocene small mammals from caves localities of Usa river valley (Сhernyshev's ridge, north-eastern part of European Russia)

Reconstructing the Holocene history of the small mammal fauna is of special value because it provides an example of the natural development of mammalian communities under the influence of climate changes. We studied 5223 teeth of small mammals from the cave sites and avian pellets in the valley of the Usa River (right tributary of the Pechora River) by standard paleontological methods. Radiocarbon dating of fossil assemblages was made by 14C AMS method. Localities are of zoogenic origin with numerous remains of vertebrates. As a result of the study, three phases of the development of micromammalian fauna in the Chernyshev's ridge were described: of Boreal, Subboreal and modern periods. During the Boreal, when the territory of the north of Eastern Europe was occupied by taiga forests, fauna of small mammals comprised forest and intrazonal species approximately in equal proportions, and only 10-13 % of all remains were represented by tundra and steppe species. It was revealed that during the Subboreal period of the Holocene mammalian fauna consisted of inhabitants of spruce and pine forests. Modern rodent fauna of the Chernyshev's ridge is inhabited only by taiga species.