Bison can be traced back to the Ice Age. Back then they were called Steppe bison, and they ranged over major parts of northern Europe, Asia and North America. They were, for the most part, larger than today’s bison; mostly to prevent heat loss.
There was little difference between the Steppe bison of Europe/Asia and the bison of North America, but by today’s standards, they were huge. Males had horn spreads reaching more than 6 feet and were as much as 40% larger than today. Also, the vertebral spines in the hump were much longer. Clues have come from frozen mummies found in Alaska and Siberia, others were preserved in the permafrost of the Arctic. Along with size and form, the mummified remains showed patterns of hair distribution, color differences, diet, and disease and in some cases, cause of death.