Of all placental mammals, handicaps are the tiniest in comparison to their mother.

在所有胎动中，与母亲相比，残疾是最小的。

This is our best guess at what the first placental mammal looked like.

这是对第一种胎生动外貌的最好猜想了。

These subtle creatures didn't belong to any of the three main mammal groups on the planet today-which are the placental mammals (like us), monotremes (like the platypus) and marsupials (like koalas and kangaroos).

这些小动属于今天地球上的三个主要动群体——胎动(像我们)、单孔目动(像鸭嘴兽)和有袋动(像考拉和袋鼠)。

Apparently, her fall caused a placental abruption, where the placenta separates from the uterus. -Oh, my god.

很明显，她的跌倒导致胎破碎，胎和宫已经分离了。-天哪。

Therefore, you need to get your oxygen from the mother's placental blood flow and all that stuff.

因此，你需要从母亲的胎血流和所有的东西中获得氧气。

It's then carefully removed to ensure that there are no placental remnants left in the uterus.

然后慢慢移除，确保胎遗会在宫腔。

These little creatures didn't belong to any of the three main mammal groups on the planet today—which are the placental mammals (like us), monotremes (like the platypus) and marsupials (like koalas and kangaroos).

这些小动属于当今地球上的三大动群体——即胎动（比如我们人类）、单孔目动（比如鸭嘴兽）和有袋类动（比如考拉和袋鼠）。

Explain to her that while we don't know the exact cause of preeclampsia, it's likely related to placental dysfunction and abnormal blood vessel formation early in pregnancy.

向她解释， 虽然我们尚清楚先兆痫的确切原因，但它很可能与妊娠早期胎功能障碍和异常血管形成有关。

But you have an early placental abruption.

但你过早出现了胎早期剥离。

The three modern mammal groups -- the placentals, marsupials and monotremes -- all made it.

三个现代动群——胎 动、有袋动和单孔动——都成功了。

Australia has a long and well-documented history of marsupial populations coexisting alongside placental mammals.

澳大利亚有袋类种群与胎动共存的历史悠久且有据可查。

Paraceratherium was a placental mammal, like us, meaning that it gestated its young inside its body.

奇蹄兽是一种有胎的动，就像我们一样，这意味着它会在体内孕育幼崽。

In North America and Europe, they were running roughshod over all the placentals that were there.

在北美和欧洲，它们（有袋类动）横行无忌，压倒了当地所有的胎动。

For crown group mammals, our most recent common ancestor is the one shared by placentals like us, marsupials like the kangaroo, and the monotremes like the platypus.

对于冠群动，我们最近的共同祖先是与有胎动（如人类）、有袋类动（如袋鼠）和单孔类动（如鸭嘴兽）共享的。

It turns out that the placental mode of reproduction, that is keeping our babies inside, and we have this problem.

原来， 胎动的繁殖方式，即让我们的宝宝在母体内成长， 却带来了一个问题。

Over the course of many hundreds of years, scientists have noted the ability of marsupials to surpass placentals in competition for resources and niche environments.

数百年来，科学家们已经注意到有袋动在争夺资源和生态位环境方面能够超越胎。

The primitive mammals did exactly what placental mammals did.

原始动完全按照胎动的方式行事。

This includes a number of the placental mammals that are thought to have originated on the supercontinent Laurasia during the Late Cretaceous Period.

这包括了一些被认为是起源于晚白垩世时期超级大陆劳亚大陆的有胎动。

If a dinosaur chases a placental mammal, you know, in the Cretaceous, they're going to catch that placental mammal and that little girl, and then they're going to eat all her babies along with her.

如果一只恐龙在白垩纪追逐一只胎动，你知道的， 它们会抓住那只胎动和那个小女孩，然后连同她一起吃掉她所有的宝宝。

The researchers suggested that the ancestors of placental mammals that lived with the dinosaurs were small, insectivorous, and nocturnal.

研究人员推测， 与恐龙共存的有胎动的祖先体型较小，以昆虫为食， 并且是夜行性的。