It's in the water that they come alive... 在水中 它们才会活跃起来
knowing that safety lies in numbers 它们知道 庞大的数量和即将到来的黑暗
and an ibex that has fallen to its death. 和一头摔死的羱羊
...adaptations that protect them and their young 这些适应性可以保护它们及幼崽
there rose from the ashes a life-form that had previously only survived 一种此前只在边缘地带幸存的生物
something that would challenge mammals as never before. 这将对哺乳动物提出前所未有的挑战
that helped drive a global cooling. 这有助于推动全球变冷