The Yukagir Bison: The exterior morphology of a complete frozen mummy of the extinct steppe bison, Bison priscus from the early Holocene of northern Yakutia, Russia

摘要

The paper presents analyses of the exterior morphology of one of the extinct and dominating species of the Late Pleistocene megafauna of Eurasia, the steppe bison, Bison priscus. The frozen mummy of the Yukagir Bison found in northern Yakutia, Russia represents the most complete specimen of this species in the world. It belongs to a young, 4.1-4.5 year old male, which dates back about 10,500 cal BP. The analyses revealed that the overall size of this specimen was comparable to a 6-year old European and American bison. Its horn spread falls within the upper limits of B. bison athabascae and B. bison bison males, as well as within the average sizes of B. priscus occidentalis from East Siberia and North America. While most of the not fully-grown Yukagir Bison body size fell within the average parameters of both grown modern species, the body and hind foot lengths were closer to the lower limits of the European bison. The color and hair pattern appeared to be close to the Blue Babe mummy (B. priscus) and modern Wood bison (modern morphotype of B. bison athabascae) and European (B. bonasus) bison. The geological age of the Yukagir Bison, along with the data from other specimens indicate that this species, which survived the Pleistocene-Holocene boundary, became rare but was still widely distributed in the northern part of centraleastern Siberia until about 8000 years ago. The juxtaposed data from arctic latitude sediments and the Bison priscus stomach content pollen indicate that it was selective grazer in the environment dominated by unfavorable shrub and forest-tundra vegetation. The scarce Holocene steppe bison remains in Eastern Siberia reflects the dramatic decrease of suitable habitats and pastures during the early Holocene climatic optimum in the high Arctic, which was a major factor of irreversible population fragmentation and decline leading to the species' extinction. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.