At first, they were small creatures, 起初 它们是小型生物

196. was a group of warm-blooded animals
     有一群温血动物
197. that had long hidden in the shadows.
     长♥期♥隐藏在阴影之中
198. The mammals.
     哺乳动物
199. At first, they were small creatures,
     起初 它们是小型生物
200. similar to voles.
     与田鼠相仿
201. With the dinosaurs gone, they were free to come out in the open.
     恐龙灭绝之后 它们可以自♥由♥地出来活动
202. But just five million years after the asteroid,
     但是在小行星撞击之后仅500万年

来自《我们星球上的生命 第一季 第六集 Life on Our Planet S01E06 灰烬中重生》第 199 行