The Dimetrodon was in fact a synapsid.

异齿龙实际上是一种下孔亚纲动物。

These ancient animals known as mammaliamorph synapsids had traits linked with mammals.

这些被称为“mammaliamorph synapsids”的古老动物具有与哺乳动物相关的特征。

The synapsids divided into four streams, only one of which survived beyond the Permian.

下孔亚纲分成四支，只有一支闯过了二叠纪。

Synapsids were one of the four main divisions of early reptilian life, the others being anapsids, euryapsids, and diapsids.

下孔亚纲是早期爬行动物的4个主要部之一，其他3个部分别是缺孔亚纲、调孔亚纲和双孔亚纲。

And the other was the synapsids, the ancestors of mammals.

另一个是突触动物，哺乳动物的祖先。

Synapsids had one hole in their lower temples; diapsids had two; euryapsids had a single hole higher up.

下孔亚纲在颞颥下部有1个孔；双孔亚纲有2个孔；调孔亚纲只有上部1个孔。

And that's because dimetrodon is a synapsid.

那是因为异齿龙是一种合弓纲动物。

Nearly all of the dicynodont synapsids went extinct.

几乎所有的双齿兽突弓动物都灭绝了。

And you might remember from our episode on synapsids that Thrinaxodon was a burrower.

你可能还记得我们关于突触动物的那一集，Thrinaxodon 是一种穴居动物。

And they rapidly split into two major groups – the reptiles and the synapsids.

它们迅速分裂成两大类 ——爬行动物和突触动物。

Amniotes with one temporal fenestrae are called synapsids.

具有一个颞孔的羊膜动物称为突触。

And at some point, synapsids even evolved mammary glands, when they were still laying eggs.

在某些时候，突触甚至在它们还在产卵的时候就进化出了乳腺。

This was the last group of synapsids to branch off that still laid eggs.

这是最后一组仍然产卵的突触分支。

Now, the other group, the synapsids, took a much more complicated path.

现在，另一组，即突触，走了一条复杂得多的道路。

This new group of synapsids branched off around 186 million years ago, during the early Jurassic Period.

这群新的合弓纲在大约 1.86 亿年前的侏罗纪早期分支出来。

" They have no living descendants, but they are a member of the larger group called synapsids, which includes mammals as living representatives, " Kammerer added.

“它们没有活下来的后代，但它们是被称为合弓纲动物的更大群体的成员，该群体包括现存代表生物哺乳动物，”卡默勒补充称。

Fossil evidence shows that early synapsids radiated much more quickly than their sauropsid cousins.

化石证据表明，早期的突触动物比它们的蜥脚类表亲辐射得更快。

By the Early Permian, synapsids became much more common in fossil assemblages.

到二叠纪早期，合弓类动物在化石组合中变得更加普遍。

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， 早期的合弓类动物可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。

Synapsids had one pair of openings in the skull, called a temporal fenestra, while the Sauropsids had two pairs.

合弓类动物的头骨上有一对开口，称为颞孔， 而蜥脚类动物有两对。