The steppe bison or steppe wisent (Bison priscus) is an extinct species of bison that was once found on the mammoth steppe where its range included British Isles, Europe, Central Asia, Northern to Northeastern Asia including Japanese archipelago, Beringia, and central North America, from northwest Canada to Mexico during the Quaternary. This wide distribution is sometimes called the Pleistocene bison belt, compared to the Great bison belt. Three chronological subspecies, Bison priscus priscus, Bison priscus mediator, and Bison priscus gigas, have been suggested. Evolution The steppe bison first appeared during the mid Middle Pleistocene in eastern Eurasia, subsequently dispersing westwards as far as Western Europe. During the late Middle Pleistocene, around 195,000-135,000 years ago, the steppe bison migrated across the Bering land bridge into North America, becoming ancestral to modern American bison, as well as extinct forms such as the largest known bison, the long-horned Bison latifrons, and the smaller Bison antiquus. Description Resembling the modern bison species, especially the American wood bison (Bison bison athabascae), the steppe bison was over tall at the withers, reaching in weight. The tips of the horns were a meter apart, the horns themselves being over half a meter long. Bison priscus gigas is the largest known bison of Eurasia. This subspecies was possibly analogous to Bison latifrons, attaining similar body sizes and horns which were up to apart, and presumably favored similar habitat conditions. The steppe bison was also anatomically similar to the European bison (Bison bonasus), to the point of difficulty distinguishing between the two when complete skeletons are unavailable. The two species were close enough to interbreed; however they were also genetically distinct, indicating that interbreeding was in fact rare, possibly as a result of niche partitioning between the species. Extinction The steppe bison distribution contracted to the north after the end of the Pleistocene, surviving into the mid Holocene before becoming extinct. A steppe bison skeleton was radiocarbon dated to 5,400 years Before Present (c. 3450 BCE) in Alaska. B. priscus remains in the northern Angara River in Asia were dated to 2550-2450 BCE, and in the Oyat River in Leningrad Oblast, Russia to 1130-1060 BCE. Discoveries Steppe bison appear in cave art, notably in the Cave of Altamira and Lascaux, and the carving Bison Licking Insect Bite, and have been found in naturally ice-preserved form. Blue Babe is the 36,000-year-old mummy of a male steppe bison which was discovered