So when the Ice Age hit two and a half million years ago, 所以 2500万年前 当冰河时代突然袭来之时
The most dangerous animal the world had ever seen. 这是世界上出现过的最危险的动物
What had been a slow cooling of the planet 过去缓慢的地球降温
the mammals were faced with a new challenge. 哺乳动物面临一个新的挑战
Such is the role of chance in the history of life on our planet. 这就是机遇在地球生命历史中 所扮演的角色
But there is one more chapter in the mammal story still to be told. 但是哺乳动物的故事 还有一章仍待讲述
The asteroid strike had allowed the mammals to go from lowly underdogs... 小行星撞击 使哺乳动物从卑微的弱者…
The mammals have conquered every habitat on Earth. 哺乳动物征服了地球上每一片栖息地