has not been felt for 66 million years. 已经是6600万年前的事了
our story could have been a short one 但如果表现不够出色
there have been more than 50 cycles of ice buildup and melt... 已经发生50多次结冰融化的循环
Age-old enemies that have been locked in battle for millennia. 数千年来 这对宿敌一直缠斗不休
and have been hunting bison in America for more than 100,000 years. 其在美洲捕杀野牛的历史 已经超过10万年
it has been too warm for ice to form. 温度都太高 无法形成冰冻
What had been a slow cooling of the planet 过去缓慢的地球降温
It's the chance he's been waiting for. 等待已久的机会终于到来
Other survivors of the asteroid had also been evolving. 小行星撞击的其它幸存者也在进化