Systematics and distribution of sheep of the genus Ovis (Artiodactyla, Bovidae) in Eastern Siberia and the Far East in the Pleistocene and Holocene

The fossil and subfossil Siberian snow sheep, Ovis nivicola and giant (arga li) sheep O. ammon found, are analyzed. Snow sheep were wide spread in the late Pleistocene and early Holocene: their range covered most of eastern Si beria and the Far East and the southern part of western Siberia. The argali area in Siberia was also larger in that time than nowdays: they inhabited the southern part of western and eastern Siberia up to the northern Transba ikal territory and southwestern Yakutia. The most ancient form among the sh eep inhabiting southern parts of eastern Siberia from the Eopleistocene was argali-like. The Siberian snow sheep appears to originate from argali-like sheep at the end of the early Pleistocene or the beginning of the Middle P leistocene in the mountains of southern Siberia. In the Middle Pleistocene, O. nivicola started settling to the north and northeast and reached Alaska by the Bering land bridge. A comparison of fossil remains of O. nivicola f rom Yakutia and Transbaikal region with the present subspecies O. n. lydekk eri and O. n. nivicola testifies that the former are similar to the latter. The fossil snow sheep from the southern part of western Siberia is worth c onsidering as an independent subspecies (O. nivicola tomensis Gromova 1947) . The validity of O. ammon fossilis Pavlova 1911, a fossil argali from Tran sbaikal and Cisbaikal regions, is confirmed. An additional description of t his species is given.