Cave Bear

The cave bear (Ursus spelaeus) is an extinct species of bear that lived during the Pleistocene epoch in Eurasia. It became extinct about 10,000 years ago.

Facts
An enormous number of cave bear remains have been found, allowing paleontologists to determine a lot about this animal. It had a very broad, domed skull with a steep forehead. Its stout body had long thighs, massive shins and in-turning feet, making it similar in skeletal structure to the brown bear. These animals were comparable in size to the polar bear. The average weight for males was 400–500 kilograms (880–1102 pounds), while females weighed 225–250 kg (496–551 lbs). Of cave bear skeletons in museums, 90% are male due to a misconception that the female skeletons were merely "dwarfs". Cave bears grew larger during glaciations and smaller during interglacial periods, probably to adjust heat loss rate. These bears of the last Ice Age lacked the usual two or three premolars present in other bears; to compensate, the last molar is very elongated, with supplementary cusps. The humerus of the cave bear was similar in size to that of the polar bear, as were the femora of females. The femora of male bears, however, bore more similarities in size to those of kodiak bears.

Portrayal in the series
To be added...

A Mammoth Undertaking
When Nigel Marven entered a cave, he awoke a hibernating cave bear. Nigel slowly exited the cave, but, unfortunately, the creature followed. The bear chased Nigel and the cameraman. Luckily, Nigel was able to escape by climbing a tree. As for the cameraman, the animal swiped the camera with its claws, but the cameraman was not injured. The cave bear then returned to its cave. However, Nigel did not believe he could realistically rescue it, and continued on his journey without attempting to.

Errors

 * Cave bears died out long before 10,000 years ago. Nigel even pointed this out right after the chase.