鸭嘴兽的灭绝可能为我们揭开恐龙的最后时刻

This is Scientific American's 60-second Science, I'm Susanne Bard.

这里是科学美国人——60秒科学系列，我是苏珊娜·巴德。

In North America, fossils of duckbill dinosaur are abundant.

在北美，鸭嘴兽的化石非常丰富。

So abundant that paleontologists sometimes ignore them in search of more exciting species, like T. Rex or Triceratops.

数量如此之多，以至于古生物学家有时会忽略它们，去寻找更令人兴奋的物种，比如霸王龙或三角龙。

“They were so common we often wouldn't collect them and just left them out in the field.”

“它们太常见了，我们通常不会收集它们的化石，而是把它们留在地里。”

University of Bath evolutionary biologist Nick Longrich.

巴斯大学进化生物学家尼克·隆瑞奇说。

But duckbills had never been found in Africa.

但在非洲从未发现过鸭嘴兽。

So, Longrich did a double take when he was visiting the Natural History Museum of Marrakesh in Morocco and came across the 66-million-year-old jawbone of a previously undocumented duckbill species.

因此，隆瑞奇在参观摩洛哥马拉喀什自然历史博物馆时多看了两眼，偶然发现了一块6600万年前的之前未记录在册的鸭嘴兽的颚骨。

“I instantly knew what it was, and I just couldn't figure out what it was doing there.”

“我立刻就知道它是什么，只是不知道它在那里做什么。”

Its presence in North Africa was problematic because during the Late Cretaceous period the planet was warmer, which means sea levels were higher.

它在北非的存在是有问题的，因为在白垩纪晚期，地球更温暖，这意味着海平面更高。

“Africa was isolated from all the other continents by water, and there didn't seem to be any way that they could get there.”

“非洲与其他大陆被海水隔离开来，他们似乎没有任何办法可以到达那里。”

Unless, perhaps, duckbills swam hundreds of miles across open ocean from what is now Europe.

除非鸭嘴兽从现在的欧洲游几百英里穿过广阔的海洋。

It's not as far-fetched as it might sound.

这并不像听起来的那么牵强。

In fact, paleontologists once thought duckbill dinosaurs were aquatic, but that theory eventually fell out of favor.

事实上，古生物学家曾经认为鸭嘴恐龙是水生动物，但这个理论最终失宠了。

Nonetheless, there's evidence that duckbills were well-adapted for swimming.

尽管如此，有证据表明，鸭嘴兽很适合游泳。

“They have these really big, powerful hind limbs. Great big feet.

“它们有非常大、有力的后肢。有巨大的脚掌。

They've got a long, deep tail they could have used for sculling.

它们有一条又长又厚的尾巴，可以用来划水。

So, they might have been pretty good swimmers.”

所以，他们可能是很好的游泳者。”

Plus, other animal species have been known to cross oceans, albeit rarely.

此外，其他动物物种也曾横渡海洋，尽管很少。

Elephants, monkeys, and even hippos, for example, have all colonized new places after swimming or floating there.

例如，大象、猴子，甚至河马，游到或漂浮到新的地方后，都在那里定居。

“It's incredibly improbable. But over millions of years, these once-in-a-million-year events will happen on average once every million years.”

“这是非常不可能的。 但在数百万年的时间里，这种百万年一次的事件平均每百万年发生一次。”

To better understand the migrations of duckbill dinosaurs, Longrich and his colleagues reconstructed their evolutionary tree.

为了更好地理解鸭嘴龙的迁徙，隆瑞奇和他的同事重建了他们的进化树。

“The duckbills seem to originate in North America.

“鸭嘴兽似乎起源于北美。

They migrate across the land bridge into Asia, jump over into Europe.

他们跨过陆桥，进入亚洲，然后进入欧洲。

And then finally this European lineage, one branch of that evolutionary tree, jumps into Africa.”

最后，这个欧洲世系，进化树的一个分支，进入了非洲。”

Longrich's team dubbed the new species Ajnabia odysseus.

隆瑞奇的研究小组将这种新物种命名为奥式异域龙。

Some duckbills were 50-feet long, but Ajnabia was perhaps the smallest of these Cretaceous vegetarians, about the size of a pony.

有些鸭嘴兽有50英尺长，但异域龙可能是白垩纪最小的素食者，只有小马那么大。

And while North American duckbills were being hunted down by hungry T. rex, in Africa, Ajnabia likely had to contend with fearsome Abelisaurs, which were smaller, but similar to T. rex.

当北美的鸭嘴兽在非洲被饥饿的霸王龙猎杀时，异域龙可能不得不与可怕的阿贝尔龙搏斗，它体型较小，但与霸王龙相似。

The study is in the journal Cretaceous Research.

这项研究发表在《白垩纪研究》杂志上。

Insights into Ajnabia could help answer questions about the end of the age of the dinosaurs.

对异域龙的深入了解有助于回答有关恐龙时代结束的问题。

“This is just before the asteroid hit.

“就在小行星撞击地球之前。

So, we're getting a snapshot of the dinosaurs in their final moments.

所以，我们得到了恐龙最后时刻的大致情况。

The sort of twilight of the dinosaurs.

恐龙的衰退期。

Along with things like T-Rex and Triceratops, these were the last dinosaurs on earth.”

与霸王龙和三角龙一样，它们是地球上最后的恐龙。”

Thanks for listening for Scientific American's 60-second Science. I'm Susanne Bard.

谢谢大家收听科学美国人——60秒科学。我是苏珊娜·巴德。