Ornithischian dinosaurs like Triceratops and Stegosaurs lack these air sacs and as a result, most of them weren't very big.

三角龙和剑龙属于鸟臀目恐龙，缺少这些气囊，因此它们大多数的体型并不大。

That makes it an Ornithischian dinosaur.

这使它成为鸟臀目恐龙。

Sometimes, the backwards pointing pubis on an ornithischian dinosaur.

有时，鸟臀目恐龙的耻骨向后指。

Well that’s where a major change occurred in ornithischian dinosaurs.

很好，这就是 鸟臀目恐龙发生重大变化的地方。

And all skulls have the predentary bone present in ornithischian dinosaurs.

所有的头骨都具有鸟臀目恐龙中的原始骨骼。

That's one of the easiest ways to tell an Ornithischian dinosaur from a Saurischian dinosaur.

这是区分鸟臀目恐龙和蜥臀目恐龙的最简单方法之一。

To explore this concept further, let's take a look at some ceratopsians, a major group of ornithischian dinosaurs.

为了进一步探索这个概念，让我们来看看一些角龙类，这是鸟臀目恐龙的一个主要类群。

These species represented the earliest members of the Sertian Theropods and sauropods as well as primitive Ornithischian dinosaurs.

这些物种代表了塞尔提亚兽脚亚目和蜥脚类恐龙以及原始鸟臀目恐龙的最早成员。

They are a diverse group of plant-eating ornithischian dinosaurs that includes animals from the little Dryosaurus to the much larger Edmontosaurus and Iguanodon.

它们是多种多样的以植物为食的鸟臀目恐龙，包括从小型龙龙到体型更大的埃德蒙顿龙和禽龙的动物。

In other words, every dinosaur inside the circle is an ornithischian or bird-hipped dinosaur as we learned back in the first module of this course.

换句话说，正如我们在本课程的第一个模块中学到的那样，圆圈内的每只恐龙都是鸟臀目或鸟臀恐龙。

And that's because the muscles rearrange themselves because they're not moving in the same kind of way and so in an Ornithischian dinosaur, the pubis reorientates itself so that it's back beside the ischium.

那是因为肌肉会重新排列，因为它们没有以相同的方式运动，所以在鸟臀目恐龙中，耻骨会重新定位，使其回到坐骨旁边。