Bison in North America migrated from Eurasia in waves via the Bering corridor. Ancestors of modern bison apparently arrived here during the last interglacial episode (Sangamon). The earliest ancestor, represented by Bison antiquus, was up to one third larger than modern representatives and persisted as late as 10,000 years ago. Meanwhile they had spread over most of America, south of the Wisconsin Episode ice. Bison antiquus lived in herds with habits like those of modern bison. That they were hunted by paleo-Indians is demonstrated by numerous kill sites, some containing remains of some 200 individuals. Distinquished by their large size, long horns and a large hump, they apparently were displaced by modern bison, which expanded in great numbers over the western plains and as far east as Illinois.