The skulls of archosaurs were lighter than their reptile ancestors.

主龙类的头骨比 它们的爬行祖先轻。

Some archosaurs, like crocodylians, have been shown to exhibit general parenting behavior.

一些主龙，如鳄鱼，已被证明表现出一般的养育行为。

After the Permo-Triassic extinction, pseudosuchians were the first group of archosaurs to diversify and become common.

纪-三纪灭绝之后，伪鳄是第一批多样化并变得普遍的主龙类。

The End-Triassic extinction saw the end of many of the pseudo sukian archosaurs that were dominant during the Triassic.

三纪末的灭绝见证了许多三纪期间占主地位的伪苏氏主龙的终结。

Pterosaurs, another group of archosaurs (or " ruling reptiles" ) like the dinosaurs, may have developed feathers earlier than their dino cousins did.

翼龙是另一种像恐龙一样的祖龙（或“统治型爬行”)，可能比它们的恐龙表亲更早进化出了羽毛。

Most paleontologists consider pterosaurs to be a type of archosaur, a group that includes dinosaurs and crocodiles, among other things.

大多数古生学家认为翼龙是一种主龙类，包括恐龙和鳄鱼等。

Around 250 million years ago, during the Triassic period, a class of reptiles called archosaurs split into two main groups.

大约 2.5 亿年前的三纪时期，一种叫做主龙的爬行分为两大类。

Arbour studied the tail anatomy of ankylosaurs and compared it to that found in living archosaurs, like crocodilians.

Arbor 研究了甲龙的尾部解剖结构，并将其与现存的主龙类（如鳄鱼）进行了比较。

Meanwhile, with these predators running around, another line of plant-eating archosaurs, the aetosaurs, came to be covered in bony armor.

与此同时，随着这些食肉四处奔跑，另一支以植为食的主龙，即始龙，开始披上了骨质盔甲。

But after the extinction event at the end of the Cretaceous, the non-avian dinosaurs and other large archosaurs were gone.

但是白垩纪末期的灭绝事件之后，非鸟类恐龙和其他大型始祖龙就消失了。

During the Triassic Period a group of animals branched off from the archosaur family tree at roughly the same time that dinosaurs did.

三纪时期，一群从主龙科树中分支出来的时间与恐龙大致相同。

But based on its physical features, most studies classify Scleromochlus as an early ornithodiran, one of those " bird-line archosaurs" that include the pterosaurs.

但根据它的身体特征， 大多数研究将 Scleromochlus 归类为早期鸟龙类，是包括翼龙内的“鸟系主龙” 之一。

And some of the archosaurs they used were maternal, meaning that parenting is done by the females, and some were paternal, where the dads do the work.

他们使用的一些主龙是母性的，这意味着育儿是由雌性完成的，而有些是父性的，父亲负责工作。

The study then compared that data with the same info from different groups of living archosaurs, the group that includes birds, non-avian dinosaurs, and also all of the crocodylians.

然后，该研究将该数据与来自不同现存主龙类群的相同信息进行了比较，该类群包括鸟类、非鸟类恐龙以及所有鳄鱼。

Today, we know that pterosaurs are a type of  archosaur, which means that they're part of the larger group that includes dinosaurs, birds, and  crocodilians, but this wasn't always so certain.

今天，我们知道翼龙是主龙的一种，这意味着它们属于更大的类群， 包括恐龙、鸟类和鳄鱼，但这并不总是那么确定。

For example, some lineages of reptiles took on the role of apex predators on land, and by 240 million years ago, a group of archosaurs, the rauisuchids, appear in the fossil record.

例如， 一些爬行谱系陆地上扮演了顶级掠食者的角色，到 2.4 亿年前，化石记录中出现了一群主龙类劳氏鳄。