Bears of the Pleistocene

[brotherbear]

Bears of the World by Lance Craighead.

The grizzly or brown bear, Ursus arctos, began to evolve in the Old World from the ancestral Ursus etruscus during the middle Pleistocene about 1.6 million years ago. The oldest known fossils of today's brown bears were found in France and are about 900,000 years old. A more recent fossil was found in China, and is about 500,000 years old. This and other fossil data suggest that brown bears were well established in Europe by the mid Pleistocene about 800,000 years ago. They may have also been in central Asia at that time. They subsequently dispersed into eastern Asia and eventually into North America following the route taken by the black bears.

The brown bear also coexisted with the giant short-faced bear, Arctodus simus. The only known association of these two species south of Alaska is from Little Box Elder Cave near Douglas, Wyoming. The grizzly was probably in competition with the giant short-faced bear throughout its range and eventually replaced it.

Bear populations expanded slowly, one female home range at a time. As grizzlies expanded their range south of the ice sheets they competed with the black bear and in some cases restricted the black bear's range. By the time of the earliest historical records, the grizzlies had expanded as far south as central Mexico.

Half a million years ago, ancestral brown/grizzly bears ranged all across northern Eurasia. At about this time, the European cave bear was also present. Cave bears probably evolved earlier and they went extinct as brown bears increased. Reply