This change in lifestyle could be one way toothlessness evolves.

这种生活方式的改变可能是无牙进化的一种方式。

So, what secondary feeding structure could have driven them towards toothlessness?

那么，什么样的二次进食结构可能 导致它们变得无牙呢？

And molecular family trees indicate that toothlessness has evolved independently more than 20 times in frogs.

分子家谱表明，无牙在青蛙中独立进化了 20 多次。

And maybe the most unexpected toothlessness happened in a lineage of purely carnivorous animals - adult amphibians!

也许最意想不到的无牙发生在纯食肉动物的血统中 - 成年两栖动物！

It turned out that toothlessness was a convergent trait that showed up in lots of different groups at different times.

事实证明，无牙是一种趋同性特征，在不同时间出现在许多不同的群体中。

But now we have a real-life example of one way toothlessness could have evolved, which will help paleontologists figure out how it happened to birds.

但现在我们有了一个现实生活中的例子，说明无牙可能是如何进化的，这将有助于古生物学家弄清楚它是如何发生在鸟类身上的。