the mammals didn't stop there. 但它们并未止步于此

248. having learned all the skills they need
     到时它们将学会一切所需技能
249. to survive at the top of the world.
     可以在世界之巅生存下去
250. Although they had conquered the land,
     虽然哺乳动物征服了陆地
251. the mammals didn't stop there.
     但它们并未止步于此
252. One branched out and went in an entirely different direction.
     有一个分支 朝一个完全不同的方向发展
253. Fifty million years ago,
     5000万年前
254. bats opened up a whole new realm...
     蝙蝠通过飞行

来自《我们星球上的生命 第一季 第七集 Life on Our Planet S01E07 地球继承者》第 251 行