By then though, skinnymorph mustelids had also dispersed into Africa, colonizing savannah habitats.

不过到那时，skinnymorph mustelids 也已经分散到非洲，在大草原栖息地定居。

They seem to have diversified first in Eurasia, but some of the oldest mustelid fossils are from North America.

它们似乎首先在欧亚大陆实现了多样化，但一些最古老的鼬科动物化石来自北美。

But it wouldn't be long before we'd finally have solid evidence of a skinny, burrowing mustelid!

但用不了多久，我们就会最终获得确凿的证据，证明有一种骨瘦如柴的、穴居的鼬科动物！

Now, as for the musclimorphs, well, they would go on to include some of the biggest fossil mustelids of all time.

现在，至于 musclimorphs，嗯，它们将继续包括一些有史以来最大的化石鼬科动物。

Now, in the world of mustelids, there are two main body shapes: long and slinky or big and beefy.

现在，在鼬科动物的世界里，主要有两种体型：又长又瘦，或者又大又结实。

This close-to-25-million-year-old mustelid was found in Nebraska, curled up in the burrow of a beaver.

这种近 2500 万年前的鼬科动物在内布拉斯加州被发现，蜷缩在一只海狸的洞穴中。

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

在始新世早期，可能在鼬科动物出现之前，我们的星球气候温暖。

As their prey adapted to life in the new grasslands of the Oligocene, the mustelids did too.

当它们的猎物适应了渐新世新草原的生活时，鼬科动物也适应了。

And this is where we see those two major mustelid body plans start to take shape.

这就是我们看到这两个主要的鼬类身体计划开始形成的地方。

Based on fossil evidence, the earliest mustelids lived in the Northern Hemisphere, but whether they originated in North America or Eurasia is still debated.

根据化石证据， 最早的鼬科动物生活在北半球，但它们究竟起源于北美还是欧亚大陆仍存在争议。

And the researchers who worked on it don't know what it means yet for the debate about where mustelids got their start and when they got skinny.

从事这项研究的研究人员还不知道这对于关于鼬科动物从哪里开始以及它们何时变瘦的争论意味着什么。

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。

The outcome of all this interchange was a large diversification of mustelids between 24 and 20 million years ago as they encountered the emerging grasslands and exploited new prey.

所有这些交流的结果是在 24 到 2000 万年前，当它们遇到新兴的草原并开发新的猎物时，它们出现了大规模的多样化。

So, it looks like the ecosystem transition towards the grasslands of the Oligocene drove the first wave of burrowing skinnymorph mustelid diversification - but it certainly wasn't the last.

因此，看起来渐新世向草原的生态系统过渡推动了第一波挖洞的瘦形鼬科动物多样化——但这肯定不是最后一次。

Now, this fossil was published while we were writing this episode and actually threw a bit of a wrench into the story, because it's the earliest fossil mustelid that looks like it might've been a tunnel-hunter, like living weasels.

现在，这块化石是在我们写这一集的时候出版的，实际上给这个故事带来了一些麻烦，因为它是最早的鼬科动物化石，看起来就像活的黄鼠狼一样是隧道猎人。