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

三角龙剑龙属于鸟龙，缺少这些气囊，因此它们大多数的体型并不大。

It's a closed relative of Triceratops, and the group called the ornithischians.

它是三角龙的近亲，属于鸟龙。

Ouranosaurus has a spike-like thumb and a dental battery, and was an iguanadont ornithischian.

Ouranosaurus 有尖刺状的拇指牙齿电池，并且是种鬣蜥鸟。

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

很好，这就是 鸟龙发重大变化的地方。

That makes it an Ornithischian dinosaur.

这使它成为鸟龙。

This beak gave ornithischians a tool for slicing off plant stems.

这种喙为鸟动物提供了切下植物茎干的工具。

Sometimes, the backwards pointing pubis on an ornithischian dinosaur.

有时，鸟龙的耻骨向后指。

All the way over on the other side of the dinosaur family tree, there's another, broader group called the ornithischians.

在龙家族树的另边，还有另更广泛的群体， 叫做鸟。

And in the 1990s, researchers studied the nasal regions of three species of theropods and one ornithischian.

在 1990 年代，研究人员研究了三种兽脚类动物种鸟动物的鼻部区域。

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

所有的头骨都具有鸟龙中的原始骨骼。

There are two key traits that distinguish all ornithischians from thischians.

有两关键特征可将所有鸟与蓟亚区分开来。

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

这是区分鸟龙蜥龙的最简单方法之。

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

为了进步探索这概念，让我们来看看些角龙类，这是鸟龙的主要类群。

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蜥脚类龙以及原始鸟龙的最早成员。

First, ornithischians have a hip with a pubic bone that points backwards.

首先，鸟动物的部有向后指向的耻骨。

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龙，包括从小型龙龙到体型更大的埃德蒙顿龙禽龙的动物。

Birds belong among saurischian dinosaurs, not among the ornithischians.

鸟类属于蜥龙，而不属于鸟。

The second trait that distinguishes ornithischians is a special bone in the lower jaw, called the predentary.

区分鸟动物的第二特征是下颌有块特殊的骨头，称为前齿骨。

The ankylosaur and ceratopsian don't have the broad beak of the hadrosaurs, so we'll draw a circle around the hadrosaurs and leave the other ornithischians out.

甲龙角龙没有鸭嘴龙的宽喙，所以我们将围绕鸭嘴龙画圆圈，将其他鸟动物排除在外。

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模块中学到的那样，圆圈内的每只龙都是鸟或鸟龙。