and evolved into these highly specialized beasts. 进化成了这些高度专门化的巨兽
The mammals' journey into the oceans was a gradual one. 哺乳动物进入海洋的过程是渐进式的
other mammals were moving into the sea... 另一些哺乳动物则正在下海
At the same time as bats were first moving into the air, 在蝙蝠首次上天的同时
The crash forced the land into the sky, 将陆地推向天空
The climate was switching into a new, colder state. 气候正在转入一个新的更寒冷的状态