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

这些干旱荒地 对于早期四足动物来说不适宜居住，但对于羊膜动物来说却不。

And amniotes with two temporal fenestrae are called diapsids.

具有两个颞孔羊膜动物被称为双孔动物。

Amniotes with one temporal fenestrae are called synapsids.

具有一个颞孔羊膜动物称为突触。

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

羊膜动物可以根据头骨上孔或孔数细分为几个组。

Which group of amniotes do you think dinosaurs belong to?

你认为恐龙属于哪一组羊膜动物？

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羊膜动物那样产卵，这些卵柔软而坚韧， 就像今天海龟一样。

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

带壳蛋动物一个里程碑，帮助第一批羊膜动物占领了土地。

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 亿年前石炭纪时期。

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， 早期合弓类动物可能会产下带有柔软外壳原始羊膜动物卵，但也没有关于它们卵石证据。

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

另一个改变地球生命历史程发展：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。

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

在以蕨类植物和古老植物为主茂密森林中，一种新四足动物正在接管：羊膜动物。

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

因此，羊膜卵最初 30% 历史展开得无影无踪。

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物动物免于灭绝，并可能为它们入侵旱地奠定了基础。

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

但羊膜动物更好地适应了干燥环境，扩展到各种新生态位，并主宰了土地。

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

因为，蛋，尤其我们期望在早期羊膜动物中看到软壳革质蛋，不能很好地变成石。

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基因组，我们可以开始讲述卵如何以及何时首先出现故事。

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，爬行动物羊膜动物，哺乳动物也。

What we do know is that the tale of the egg diverged into two separate storylines, around 315 million years ago, when amniotes split into two major groups.

我们所知道，大约 3.15 亿年前， 当羊膜动物分裂成两大类时， 鸡蛋故事分成了两个独立故事情节。