Humans weren't at risk of dying out during the PETM, because we didn't exist.

在古新世–始新世极热事件时人类并没有濒临灭危险，因为我们还不存在。

Over the course of the Eocene epoch, the climate slowly began to cool.

在始新世时期，气候 开始慢慢变冷。

Other residents of Eocene Antarctica probably came from South America as well.

始新世南极洲其他居民可能 也来自南美洲。

In the United States, Boverisuchus shows up fully-formed and ready to run in the early Eocene.

在美国，始新世早期，Boverisuchus 已经完全成形并准备好奔跑。

By the late Eocene, practically all of the primates on those continents died out.

到始新世晚期， 这些大陆上几乎所有类动都灭。

As a result, our world is warming faster than it did back in the Eocene.

果，我们世界变暖速度 比始新世早。

Floristic Region, but their family was clearly much more widespread during the Eocene Epoch.

植区地区发现，但它们科显然 要远得多 在始新世时期广泛存在。

Clearly, Antarctica’s biodiversity took a hit after the Eocene.

显然，南极洲生多样性 在始新世之后受到打击。

Though the Cretaceous asteroid cleared the stage, mammals did not really get going until 10m years later, in the Eocene epoch.

尽管白垩纪时期小行星灭居统治地位恐龙，但哺乳动却一直到1000万年后始新世才真正兴起繁盛起来。

But what happened to these Eocene animals?

但是这些始新世动发生什么？

What we do know is that the late Eocene and early Oligocene was a time of global cooling.

我们所知道是，始新世晚期和 渐新世早期是全球降温时期。

Around 34 million years ago, the Eocene-Oligocene Transition  marked the first major period of global cooling and glaciation.

大约 3400 万年前，始新世-渐新世过渡标志着全球变冷和冰川作用第一个主要时期。

So given its size, it was able to support many different ecosystems in the Eocene.

所以考虑到它大小，它能够支持 始新世许多不同生态系统。

The Paleocene-Eocene Thermal Maximum, 55 million years ago, was so warm, crocodiles swam the waters of the Arctic Circle.

5500 万年前古新世-始新世极热期非常温暖，以至于鳄鱼在北极圈水域中游来游去。

So by the time the Eocene Epoch was over, North America no longer had the right habitat for primates.

因此， 当始新世束时，北美不再有适合类动栖息地。

And they arrived in South America by the middle Eocene Epoch, around 42 million years ago.

他们在大约 4200 万年前始新世中期到达南美洲。

This period  of warming, known as the Paleocene-Eocene Thermal Maximum or PETM, was likely caused by  a combination of natural factors.

这一变暖时期被称为古新世-始新世极热事件或PETM，可能是由多种自然因素造成。

And a big environmental change was also underway in the last half of the Eocene, thanks to the chemistry of mountain-building.

由于造山化学作用，始新世后半期也发生巨大环境变化。

Antarctica in the Late Eocene, was home to at least two more species of giant penguin.

始新世晚期南极洲是至少两种巨型企鹅家园。

In the early Eocene Epoch, probably before mustelids appeared, our planet had a warm climate.

在始新世早期，可能在鼬科动出现之前，我们星球气候温暖。