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 in each case, another feeding structure evolved and overlapped with teeth.

在每种情况下，另一种喂养结构都会 进化并与牙齿重叠。

Another weird thing is, a beak isn't the only innovation that can beat teeth - it looks like other secondary feeding structures can, too.

另一件奇怪的事情是，喙并不是唯一可以打败牙齿的创新——它看起来像其他二次喂养结构也可以。

Because in each case, other feeding structures evolved to take their place -- it looks like, in the game of evolution, a beak often beats teeth.

因为在每一种情况下， 其他的进食结构都会进化来取而代之——看起来，在进化的游戏中， 喙经常会打败牙齿。