And amniotes with two temporal fenestrae are called diapsids.

具有两个颞孔羊膜动被称为双孔动。

These arid wastelands would’ve been uninhabitable for early tetrapods, but not for the amniotes.

这些干旱 对于早期四足动来说是不适宜居住，但对于羊膜动来说却不是。

Amniotes with one temporal fenestrae are called synapsids.

具有一个颞孔羊膜动称为突触。

Which group of amniotes do you think dinosaurs belong to?

你认为恐龙属于哪一组羊膜动？

Amniotes can be subdivided into several groups based on the number of holes or fenestra in the skull.

羊膜动可以根据头骨上孔或孔数量细分为几个组。

Some reptiles continued laying eggs like those of early amniotes, which were soft and leathery, like turtles still do today.

一些爬行动继续像早期羊膜动那样产卵，这些卵柔软而坚韧， 就像今天海龟一样。

Amniotes first appeared nearly 315 million years ago, in the Carboniferous Period.

羊膜动出现在大约 3.15 亿年前石炭纪时期。

The evolution of the shelled egg was a milestone in animal evolution, helping those first amniotes take over the land.

带壳蛋进化是动进化一个里程碑，帮助第一批羊膜动占领了土。

The other was a development that altered the course of life's history on planet earth: The amniote egg.

另一个是改变球生命历史进程发展：羊膜卵。

But all that changed after aquatic amniotes started to spread.

但在水生羊膜动开始传播后，一切都变了。

Like sauropsids, early synapsids probably laid primitive amniote eggs with flexible shells, but there's no fossil evidence of their eggs either.

像蜥脚类动一样， 早期合弓类动可能会产下带有柔软外壳原始羊膜动卵，但也没有关于它们卵化石证据。

And in lush forests dominated by ferns and ancient plants, a new kind of tetrapod was taking over: the amniotes.

在以蕨类植和古老植为主茂密森林中，一种新四足动正在接管：羊膜动。

So the initial 30% of the history of the amniote egg unfolded without leaving a trace.

因此，羊膜卵最初 30% 历史展开得无影无踪。

Aquatic temnospondyls managed to hang on for tens of millions of years by sticking to watery habitats and avoiding the amniotes on land.

水生突椎动通过坚持水生栖息并避开陆上羊膜动，成功生存了数千万年。

Now, reptiles are amniotes, and so are mammals.

现在，爬行动是羊膜动，哺乳动也是。

But the amniotes, being better adapted to drier conditions, expanded into a variety of new niches, and dominated the land.

但是羊膜动更好适应了干燥环境，扩展到各种新生态位，并主宰了土。

They saved those animals known as amniotes from extinction and may have set the stage for their invasion of dry land.

他们拯救了那些被称为羊膜动动免于灭绝，并可能为它们入侵旱奠定了基础。

Because, eggs, especially soft-shelled, leathery eggs like we'd expect to see in early amniotes, don't fossilize well.

因为，蛋，尤其是我们期望在早期羊膜动中看到软壳革质蛋，不能很好变成化石。

So by digging into the genomes of these living amniotes, we can start to tell the story of how and when the egg came first.

因此， 通过深入研究这些活羊膜动基因组，我们可以开始讲述卵是如何以及何时先出现故事。

But on an increasingly dry planet, that gave amniotes a critical advantage.

但在一个日益干燥星球上，这给了羊膜动一个关键优势。