Sometime after 4 million years ago, ancient equid species began trotting across the Bering land bridge.

在 400 万年前的某个时候，古老的马科物种开始穿越白令陆桥。

Scientists believe this happened more than 15,000 years ago over the Bering Land Bridge which no longer exists.

科学家认为这种现象发生在一万五千年前的白令海峡大陆桥上，而现在大陆桥已经不存在了。

That was a few thousand years before rising sea levels covered the Bering land bridge between Asia and North America.

在那之后几千年，海平面才上升覆盖亚洲和北美之间的白令大陆桥。

This includes the idea that the first people in the Americas came over what is known as the Bering Land Bridge around 15,000 years ago.

其中包括美洲第一批人在大约15，000年前穿越白令陆桥这一观点。

But about 14 million years later, they migrated across the Bering Land Bridge and quickly spread south.

但大约 1400 万年后，它们迁移穿过白令陆桥并迅速向南传播。

Mustelid migrations across the Bering land bridge continued until around 5 million years ago, when the Bering Strait severed that route.

鼬科动物穿过白令陆桥的迁徙一直持续到大约 500 万年前，当时白令海峡切断了这条路线。

And mustelids took full advantage; they crossed the Bering Land Bridge between North America and Eurasia in both directions, moving into new habitats on either side.

芥子充分利用了；它们双向穿过北美和欧亚大陆之间的白令陆桥，进入两边的新栖息地。

These early cats certainly lived in North America, as well as Eurasia, though we don't know if it  was they or their ancestors who made the trek across the Bering land bridge.

这些早期的猫科动物肯定生活在北美以及欧亚大陆，尽管我们不知道是它们还是它们的祖先长途跋涉穿越了白令陆桥。