Which group of amniotes do you think dinosaurs belong to?

你认为恐龙属于哪一组羊？

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

这些干旱的荒地 对于早期的四足来说是不适宜居住的，但对于羊来说却不是。

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

因此，羊卵的最初 30% 的历史展开得无影无踪。

Amniotes with one temporal fenestrae are called synapsids.

具有一个颞孔的羊称为突触。

And amniotes with two temporal fenestrae are called diapsids.

具有个颞孔的羊被称为双孔。

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中看到的软壳革质蛋，不能很好地变成化石。

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

羊以根据头骨上的孔或孔的数量细分为几个组。

Now, reptiles are amniotes, and so are mammals.

现在，爬行是羊，哺乳也是。

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。

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

但在一个日益干燥的星球上，这给了羊一个关键的优势。

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

带壳蛋的进化是进化的一个里程碑，帮助第一批羊占领了土地。

Some of our earliest fossil records of amniote eggs are from dinosaurs like Mussaurus patagonicus, which lived around 215 million years in Argentina.

我们最早的一些羊卵化石记录来自恐龙， 例如巴塔哥尼鼠龙，它们在阿根廷生活了大约 2.15 亿年。

As the Permian progressed, amniote predators like Dimetrodon, Ophiacodon, and eventually saber-toothed gorgonopsians became widespread.

随着二叠纪的进展，羊捕食者如异齿龙、蛇夫和最终的剑齿蛇目变得普遍。

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的免于灭绝，并能为它们入侵旱地奠定了基础。

By the time this catastrophe occurred, most lineages of temnospondyls had already gone extinct, under pressure from the amniotes.

到这场灾难发生时，在羊的压力下，大多数突椎的谱系已经灭绝。

But all that changed after aquatic amniotes started to spread.

但在水生羊开始传播后，一切都变了。

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

一些爬行继续像早期的羊那样产卵，这些卵柔软而坚韧， 就像今天的海龟一样。

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的基因组，我们以开始讲述卵是如何以及何时首先出现的故事。

During the Triassic as dinosaurs were evolving to fill large bodied ecological niches on land the other amniote groups were evolving to fill the sea and the air.

在三叠纪期间，随着恐龙进化以填充陆地上的大型生态位，其他羊群也在进化以填充海洋和空气。

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

羊首次出现在大约 3.15 亿年前的石炭纪时期。