We know this in part because they had classic burrowing traits like big forelimbs and front claws, as well as a short tail and neck.

我们知道一点部分是因为它们具有典型掘土特征， 比如粗壮前肢和前爪，以及短尾巴和短脖子。

For example, one group was mostly fossorial - they were digging animals.

例如，其中一群体主要是掘土——它们是挖掘动物。

Now, the digging beavers stayed pretty small, only measuring about 20 to 30 centimeters long.

现，掘土海狸体型保持得相当小，只有大约20到30厘米长。

Some scientists think that the first snakes descended from burrowing lizards.

一科学家认为最早蛇类是从掘土蜥蜴演化而来。

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.

它们接下来两千万年里继续多样化——进化成了各种形态，从小小掘土者到剑齿巨兽，最终演化出了你我。

Unlike Palaeocastor and its burrowing cousins, these animals were semiaquatic.

与古仓鼠及其掘土亲戚不同，动物是半水生。