英语听力：长毛象王国—5

In one remarkable discovery recreated here, the head and hide of a large carcass was exposed – a unique opportunity for scientists to tap some Ice Age secrets. The remains were of an extinct steppe bison, a longer-horned relative of the North American bison of today. An adult bull must have died and been immersed in silt and mummified by the cold for thousands of years. Thick fat deposits found under the skin suggested that the bison did not starve to death and deep, wide scratch marks hinted at a violent end. An Ice Age predator killed the bison, but which one?

Wolves are the bison’s major predators in North America today. And they were certainly around during the Ice Age. Could they have been responsible?

Wolves hunt in packs, surrounding prey and gradually exhausting it through constant hurrying and nipping. But there is no way they could have made these marks.

What about the grizzly bear, another meat-eater that was around in prehistoric North America? The grizzly can be an impressive hunter. But during the Ice Age, there was another even bigger bear -- the giant short-faced bear, the biggest bear that ever lived. So could a bear have made the scratch marks on the gold-mine bison?