And occasionally we still find whales with the vestiges of tiny hind limbs.

并且我偶尔仍能发现鲸鱼残留着微型后肢。

Eventually, their front limbs became flippers and their hind limbs became weak and unnecessary.

最终，前肢变成了鳍状肢，而后肢变得虚弱和多余。

Now, this can be a little confusing because both types have three claws on their hind limbs.

现在，这可能有点混乱，因为这两种类型树懒后肢上都有三个爪子。

Snake embryos, for example, sprout hind limb buds.

比如说，蛇胚胎萌发了后肢芽。

Birds only use their hind limbs, their legs, for walking on the ground.

鸟类只用后肢， 腿，在地上行走。

Another major category in differences in dinosaurs is in the hind limbs.

恐龙差异个主要类别是后肢。

But if the hind limbs couldn't do the same thing, what did they do?

但如果后肢不能做同样事情，会做什么呢？

JACQUES GAUTHIER: What's this dinosaur doing with these aerodynamic feathers coming off their hind limbs?

JACQUES GAUTHIER：这只恐龙用后肢上脱落空气动力羽毛做什么？

If Microraptor couldn't splay its hind limbs, how did it use its leg feathers in flight?

如果小盗龙无法张开后肢，是如何利用腿部羽毛来飞行呢？

GAUTHIER: They certainly can't flap with their hind limbs.

高希尔：当然不能用后肢拍打。

However, according to a 2006 study, they didn't completely lose their hind limbs until about 1 million years later, or 34 millions years ago.

然而，根据2006年项研究，直到大约100万年后，也就是3400万年前才完全失去了后肢。

We can't really make out exactly how the hind limb would have fit.

我无法真正弄清楚后肢如何适合。

Early on it was thought that Hadrosaurus stood straight up on their hind limbs using their tails for support.

早期人认为鸭嘴龙用尾巴支撑后肢直立。

To adapt to an aquatic lifestyle, Ichthyosaurs evolved paddle like front and hind limbs as well as a fin tail.

为了适应水生生活方式，鱼龙进化出了像桨样前后肢以及鳍状尾巴。

So we're articulating the whole hind limb from these elements, is that correct?

所以我用这些元素来表达整个后肢，对吗？

There is anatomically, simply put, no way that it could elevate the hind limb into a horizontal position.

简而言之，从解剖学角度来说，不可能将后肢抬高到水平位置。

If you remember, I mentioned earlier, that the old view of hadrosaurs had them standing almost upright, on their hind limbs.

如果你还记得话，我之前提到过，鸭嘴龙旧观点认为几乎直立，用后肢站立。

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可能性，因为前臂太短，后肢太长，不适合挖洞动物。

And we did see about a 5 to 10 percent difference in the weights of the hind limbs in terms of muscle mass.

我确实看到后肢肌肉质量有大约 5% 到 10% 差异。

So even in this deformed specimen, there is no evidence that the animal could put the hind limb in a horizontal plane.

因此，即使在这个变形标本中，也没有证据表明该动物可以将后肢置于水平面上。