But milk wasn't the early mammals' only secret weapon. 但是母乳并不是 早期哺乳动物唯一的秘密武器
...that early mammals were confined to the shadows. 以至于早期的哺乳动物只能躲在暗处
In the clearing, a herd of early mammals graze. 空地上 一群早期哺乳动物在吃草
And in early South America, 46 million years after the asteroid, 在早期的南美 小行星撞击的4600万年后
Most early mammals didn't have armor or size to protect them... 多数早期哺乳动物 没有护甲来保护它们
we can still find the descendants of those early supersocializers. 我们仍然可以找到 早期超级社会性动物的后代
it's one of the largest predators on land in these early days of the dinosaurs' reign. 是恐龙统治时代早期 最大的陆上捕食者之一