Sabers were closing in on him.

只剑齿虎包围了他。

And then there was the most infamous cat of all, the sabertooth.

而另一个例子就是鲜为人知的剑齿虎。

Well, well-meaning caveman, imagine a saber-toothed tiger is running after you and you need to respond.

好吧，善意的穴居人，想象一只剑齿虎在追你，你需要做出反应。

This giant tooth right here is the canine tooth of a saber-toothed cat from an animal called Smilodon.

这个巨大的牙齿是剑齿虎的犬齿，这是一种有巨大牙齿的猫科动物。

We're at the top of the food chain, we don't have to defend ourselves from saber-toothed Tigers anymore.

现在的人类处于食物链的顶端，不必再去保护自己免受剑齿虎的威胁了。

Here is the skull of a giant sloth and vertebrae and bones from giant saber-toothed cats and dire wolfs.

这是一个巨大的树懒的头骨，巨大剑齿虎的椎骨和惧狼的骨头。

Yeah, what I'm holding here in my hand is pretty much what was walking around inside of the living Smilodon.

对，我现在手里拿着的就是活着的剑齿虎身体里长出的牙齿。

You want the arteries that supply your muscles to dilate so that you can run away from the saber-toothed tiger.

你希望供应肌肉的动脉扩张，这样你就可以逃离剑齿虎。

Just remember to be wary of the saber-toothed tigers that would be running around.

请记住要提防四处奔跑的剑齿虎。

These stripes serve to warn off most attackers, but perhaps the sabertooth is yet to learn exactly what they mean.

这些条纹用来警告大多数的捕，是这只剑齿虎似乎还没有意识到这些条纹的具体含义。

Why are saber-tooth tigers extinct and regular tigers not extinct?

为什么剑齿虎灭绝而普通老虎没有灭绝？

He's an overexaggerated smilodon with comical green hair.

他就像个长着绿毛极度夸张的剑齿虎一样。

Now, being so big probably helped them deal with large Miocene predators, like saber-toothed barbourofelids.

现在， 体型如此之大可能有助于它们对付大型中新世食肉动物，例如剑齿虎科动物。

If our ancestors had not feared cliff-edges or sabre-toothed tigers, we might not be here today.

如果我们的祖先没有害怕悬崖边缘或剑齿虎，我们今天可能就不会在这里。

All right. So why are saber-toothed tigers extinct but regular tigers are not extinct?

好的。那么，为什么剑齿虎已​​经灭绝，而普通老虎却没有灭绝呢？

Well, there's been no shortage of theories about how sabertooths used their fangs.

好吧，关于剑齿虎如何使用尖牙的理论并不缺乏。

So, given a few million years and the right evolutionary nudge, we might still see a smile like Smilodon's again.

因此， 经过百万年的时间和正确的进化推动，我们可能仍会再次看到像剑齿虎那样的微笑。

This may be the ice age, but by midday, temperatures soar, drawing another predator to the spring to drink—the notorious saber-toothed cat.

这可能就是冰河时代，是到了中午，气温则迅上升，另一只捕也来到了泉水处饮水——令人闻风丧胆的剑齿虎。

As famous as Smilodon is, it was only the last and largest of the great sabertooths.

与剑齿虎一样出名，它只是最后一种也是最大的剑齿虎。

One expert looked at the palate of Smilodon and thought its mouth may have been suited for drinking blood.

一位专家观察了剑齿虎的上颚，认为它的嘴可能适合喝血。