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Grizzly and Black Bear "Geneology"

October 07, 2010 | by Diane Tipton
cutthroat

A certain sense of mystery is associated with bears--whether you are a bear hunter pursuing a modern day black bear or a bear researcher pursuing the fossil records of ancient bears.

Today, Montana Fish, Wildlife & Parks works with only two surviving descendents of the many ancient bear species, the grizzly brown bear and the American black bear. The grizzly bear is on the federal list of endangered species south of Canada, and cannot be hunted. However, Montana's plentiful black bear population continues to provide spring and fall hunting opportunities. This fall Montana's general black bear hunting season is Sept. 15 to Nov. 28.

In addition, to a handful of FWP bear managers, a global network of experts studies the extinct bears. This includes wildlife researchers, archeologists, geneticists, and others. Even with all this expertise, the many elusive branches of the bear's family tree are difficult to verify. Here are a few basics on bears once found in the North American west.

Arctodus , also known as the s hort-faced bear , is a genus of extinct bears known only from fossils. One species, the giant short-faced bear ( Arctodus simus ) was the biggest bear ever to have lived.

"At a time when Bering Strait was passable, the great short-faced bears came into North America from Asia to become one of the largest land carnivores present in this area during the Ice Age," said Dr. Charles Jonkel of Missoula, a pioneer of modern bear biology.

Archeologists believe that during the Pleistocene Ice Age a land bridge connected Siberia and North America. The rise and fall of sea levels exposed and submerged the bridging land mass called "Beringia" during several periods of the Pleistocene. Today the area is the 58-mile Bering Strait where the North Pacific and Arctic oceans meet.

Dr. Richard Harington, curator of ice-age animals at the Canadian Museum of Nature in Ottawa, Canada, said bones of the giant short-faced bear have been found in southeastern Montana in Custer County and in central Mexico. Most short-faced bear fossils found in the United States are radio-carbon dated to the later part of its existence, from 90,000 to 11,000 years ago.

"The giant short-faced bear was unusually tall, with relatively long legs, indicating an ability to cover large tracts of range readily. It lacked a well-marked forehead and its short broad muzzle resembled a lion's," Harington said.

This huge bear was about six and a half feet tall at the shoulder when standing on all fours, and was about 11 feet standing upright. It could weigh as much as 2,000 pounds, some experts believe.

The ancestors of modern brown bears in North America are thought to have migrated from Asia to Alaska and the Yukon about 100,000 years ago. Ancient brown bear fossils are not uncommon in Beringia. Although the oldest brown bear fossils in areas like southern Canada and the northern U.S. are about 13,000 years old, new research suggests these bears moved south much earlier, with one fossil dating 25,000 years ago. The Kodiak, Russian and grizzly bear are descendents of these early brown bears.

Harington said the Little Box Elder Cave in Wyoming is the only known location where the bones of the great short-faced bear and early brown bears from Eurasia have been found together.

Some of the ancient predecessors of today's black bear were once as big as grizzly bears. They evolved from the Asiatic black bears, and were generalists when it came to their diet. They had an easier time adjusting to change through the centuries, and our American black bears continue to thrive today.