Puffins spend most of their lives at sea but when they return to land, they become burrowers.

海鹦一生中的大部分时间都在海上度过，但当它们回到陆地时，它们就成了会挖洞的鸟。

And you might remember from our episode on synapsids that Thrinaxodon was a burrower.

你可能还记得我们关于突触动物的那一集，Thrinaxodon 是一种穴居动物。

So, the evidence pointed to life as a burrower.

因此，证据表明生活是一种穴居动物。

And burrowing would come to be a quintessential mammalian trait — today, at least half of mammal species are burrowers.

穴居将成为哺乳动物的一个典型特征——今天，至少有一半的哺乳动物是穴居动物。

Paleontologists have ruled out burrowing, though, because their forearms were too short and their hind limbs were too long for a burrower.

不过，古生物学家排除了挖洞的可能性，因为它们的前臂太短，后肢太长，不适合挖洞动物。

And they went on to diversify over the next twenty million years -- evolving into a range of forms, from tiny burrowers to saber-toothed giants, and eventually, you and me.

在接下来的两千万年里， 它们继续多样化——演变成一系列的形式，从微小的穴居动物到剑齿巨人，最终，你和我。

These early mustelids - sometimes called paleomustelids - include Plesictis from Europe, dated to between about 34 and 23 million years ago, which looks to have been a tree-climbing hunter, not a burrower.

这些早期的鼬科动物——有时被称为古鼬科动物——包括来自欧洲的 Plesictictis，其历史可追溯到大约 34 到 2300 万年前，看起来是一种爬树猎手，而不是挖洞动物。