If you were to visit the Pleistocene Ice Age, you would have been able to see muskox (Obivos moschatus) roaming the tundra with wooly mammoths, giant steppe bison, saber-toothed cats, or even enormous short-faced bears weighing 1,900 pounds. Muskox have not changed much since the Pleistocene.
This survivor of the Pleistocene can still be seen wondering the tundra, beach, and beach ridges of Cape Krusenstern National Monument.
Along with other animals, muskox crossed the Bering Land Bridge to enter North America. Their bones have been found as far south as Kansas and Illinois. When muskox lived there, the climate was completely different from what it is today. Great sheets of ice up to a mile thick covered most of North America. The muskoxen lived on tundra that covered the southern edge of the ice.
As the ice melted, prairie grasses and forests advanced northward, replacing the tundra. Muskoxen also moved northward, or else died out. Meanwhile, muskoxen continued to live in smaller ice free parts of Alaska, the Yukon Territory of Canada, and in northern Asia. Finally, when the ice sheets had largely disappeared, the muskoxen were able to colonize the high arctic and even Greenland.