Bears of the Pleistocene

[brotherbear]

Yellowstone Bears in the Wild by James C. Halfpenny.

On the heels of the American black bear came another bear of the genus Ursus, the brown bear/grizzly bear ( see sidebar on page 13 ). At the height of the last ice advance perhaps 50,000 years ago, several populations of brown/grizzly bears occupied Beringia, the area of the Bering Land Bridge including the current state of Alaska. Near the end of the Ice Age, some grizzly bears moved south toward Yellowstone. Common dogma says brown bears reached the continents interior by traveling through a land corridor between the central continental and western mountain ice sheets about 13,000 years ago, give or take 1,000 years. However, a fossil leg bone found by Greg McDonald in an Oregon cave suggests brown bears may have reached the southern areas of the continent 30,000 years ago by a route along the coast.
No matter when or by what route, the arrival of grizzly bears evidently sealed the fate of the giant short-faced bear. Perhaps it was the new competition and perhaps it was climate change, but the net effect was the extinction of the giant bear by the end of the Ice Age. From then on, only grizzly and black bears roamed North America, including the Yellowstone area. Reply