And amniotes with two temporal fenestrae are called diapsids.

具有两个颞孔的羊膜动物被称双孔动物。

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

这些干旱的荒地 对于早期的四足动物来说是不适宜居住的，但对于羊膜动物来说却不是。

Amniotes with one temporal fenestrae are called synapsids.

具有一个颞孔的羊膜动物称突触。

Which group of amniotes do you think dinosaurs belong to?

恐龙属于哪一组羊膜动物？

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

羊膜动物据头骨上的孔或孔的数量细分几个组。

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

一些爬行动物继续像早期的羊膜动物那样产卵，这些卵柔软而坚韧， 就像今天的海龟一样。

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

羊膜动物首次出现在大约 3.15 亿年前的石炭纪时期。

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

带壳蛋的进化是动物进化的一个里程碑，帮助第一批羊膜动物占领了土地。

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

另一个是改变地球生命历史进程的发展：羊膜卵。

But all that changed after aquatic amniotes started to spread.

但在水生羊膜动物开始传播后，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.

像蜥脚类动物一样， 早期的合弓类动物能会产下带有柔软外壳的原始羊膜动物卵，但也没有关于它们卵的化石证据。

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

在蕨类植物和古老植物主的茂密森林中，一种新的四足动物正在接管：羊膜动物。

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

因此，羊膜卵的最初 30% 的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.

水生突椎动物通过坚持水生栖息地并避开陆地上的羊膜动物，成功地生存了数千万年。

Now, reptiles are amniotes, and so are mammals.

现在，爬行动物是羊膜动物，哺乳动物也是。

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

但是羊膜动物更好地适应了干燥的环境，扩展到各种新的生态位，并主宰了土地。

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羊膜动物的动物免于灭绝，并能它们入侵旱地奠定了基础。

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

因，蛋，尤其是我们期望在早期羊膜动物中看到的软壳革质蛋，不能很好地变成化石。

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物的基因组，我们开始讲述卵是如何及何时首先出现的故事。

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

但在一个日益干燥的星球上，这给了羊膜动物一个关键的优势。