Brown Bear - Taxonomy and Evolution

Taxonomy and Evolution

Brown bears are thought to have evolved from Ursus etruscus. The oldest fossils occur in China from about 0.5 million years ago. They entered Europe about 250,000 years ago, and North Africa shortly after. Brown bear remains from the Pleistocene period are common in the British Isles, where it is thought they outcompeted cave bears. The species entered Alaska 100,000 years ago, though they did not move south until 13,000 years ago. It is thought brown bears were unable to migrate south until the extinction of the much larger Arctodus simus. Several paleontologists suggest the possibility of two separate brown bear migrations: grizzlies are thought to stem from narrow-skulled bears which migrated from northern Siberia to central Alaska and the rest of the continent, while Kodiak bears descend from broad-skulled bears from Kamchatka, which colonized the Alaskan peninsula. Brown bear fossils discovered in Ontario, Ohio, Kentucky and Labrador show the species occurred farther east than indicated in historic records.