群居行为帮助恐龙统治地球

This is Scientific American’s 60-Second Science. I'm Christopher Intagliata.

这里是科学美国人——60秒科学系列，我是克里斯托弗·因塔利亚塔。

Just like cows, sheep and bison roam in herds today, so, too, did plant-eating dinosaurs.

就像今天的奶牛、绵羊和野牛成群结队地游荡一样，食草恐龙也是如此。

And it appears they began flocking together much earlier than we used to think—just as the Jurassic period was beginning to unfold.

它们聚集在一起的时间似乎比我们过去认为的-—侏罗纪时期开始出现，要早得多。

(This is) a critical time in the evolution of dinosaurs.

这是恐龙进化的关键时期。

(This is) pretty early on. So the idea is: this type of social behavior, may actually contributed to the evolutionary success of dinosaurs.

这是相当早的。 所以这个想法是:这种这种社会行为类型，可能实际上有助于恐龙进化成功。

Jahandar Ramezani of the Massachusetts Institute of Technology is a geochronologist. In his words ...

麻省理工学院的贾汉达尔·拉米扎尼是一位地质年代学家。 他说……

I date things. And I date old things, things in the millions and billions of years—not the really young stuff.

我确定事物的年代。 我对古老的事物，对数百万、数十亿年前的事物进行了年代测定，而不是那些事实上年轻的事物。

In this case, Ramezani was dating tiny zircon crystals, in fact,in a fossil bed in Patagonia, near the southern tip of South America.

在这个案例中，拉米扎尼在靠近南美洲南端的巴塔哥尼亚的化石层中测定微小的锆石晶体的年代。

Those crystals dated back to nearly 193 million years ago.

这些晶体可以追溯到近1.93亿年前。

And the fossils preserved there—an array of nearly 200 specimens of a plant eater named Mussaurus patagonicus—provide a snapshot of the dinosaur at all stages of its life.

保存在那里的化石——一组近200个食草动物的标本，名为巴塔哥尼亚鼠龙(Mussaurus patagonicus)——提供了这种恐龙所有生命阶段的快照。

Eggs and hatchlings, clumps of juveniles and then—further out—adults.

卵和刚孵化的幼崽，成群的幼崽恐龙化石，远远多于成年的恐龙化石。

So this kind of undisturbed distribution of fossils and this kind of age segregation basically shows these dinosaurs had a social structure.

所以这种未受干扰的化石分布和这种年龄隔离基本上说明了这些恐龙有一个社会结构。

They lived in a colony. And everybody has got things to do—duties—with respect to the young and the juveniles.

他们居住在群落里。对于幼崽来说，每个都有自己的事情要做—职责。

The study—in the journal Scientific Reports—suggests dinosaurs developed complex social behavior 40 million years earlier than previously thought.

这项发表在《科学报告》杂志上的研究表明，恐龙发展出复杂的社会行为的时间比之前认为的要早4000万年。

And Ramezani says the work also advances long-standing questions about the social structure of dinosaurs.

拉米扎尼表示，这项工作还推进了关于恐龙社会结构这一长期存在的问题。

Was it more like primitive taxa like the crocodiles?

它是不是更像鳄鱼那样的原始类群?

Or did it look like more evolved types of animals like birds and mammals?

还是它看起来像进化的动物类型，比如鸟类和哺乳动物?

And we’re beginning to see that, yes, it looks more like a mammal- or bird-type colony.

我们开始发现，是的，它看起来更像哺乳动物或鸟类的群落。

Whatever type of social structure it was, the scientists hypothesize that it helped large plant eaters first spread across the planet—kick-starting tens of millions of years of dominion on Earth.

无论它是哪种社会结构，科学家们假设它首先帮助大型食草动物在地球上扩张，开启了其在地球上数千万年的统治。

Thanks for listening for Scientific American's 60-second Science. I'm Christopher Intagliata.

谢谢大家收听科学美国人——60秒科学。我是克里斯托弗·因塔利亚塔。