Now, there are different types of amniotic eggs.

现在，有不同类型的羊膜卵。

In all probability, it reproduced by laying amniotic eggs.

它很可能通过产羊膜卵来繁殖。

So mutations may have changed how the pieces of the amniotic egg were used, leaving mammals with an entirely new reproductive strategy as a result.

因此， 突变可能改变了羊膜卵碎片的使用方式，从而使哺乳动物拥有全新的繁殖策略。

And the sauropsids and the synapsids put their own spins on the amniotic egg, ones that we can see today in living birds, like the chicken!

蜥脚类动物和合弓类动物将它们自己的自旋放在羊膜卵上，我们今天可以在现存的鸟类（如鸡）身上看到这些！

Because, the main membranes of an amniotic egg -- known as the sac, the chorion, and the allantois -- are all present in animals that give birth to live young.

因为，羊膜卵的主要膜——被称为囊、绒毛膜和尿囊——都存在于生下活幼仔的动物身上。