腱龙体型庞大且笨重。

Tenontosaurus didn't necessarily make a mistake.

它不一定是犯了致命的错误。

It was numbers that took him down.

它是败给了庞大的数量。

One dinosaur even as big as Tenontosaurus can not withstand an onslaught from a pack of Raptors.

即使像腱龙这样庞大的恐龙，也无法单独抵抗大群的迅猛龙猛烈的攻击。

Raptor pack kills would've continued for millions of years until their world eventually vanished.

迅猛龙杀手团伙将继续杀戮数百万年，直到它们的世界最终消失殆尽。

No one knows exactly what happened, but scientists have pieced together at least part of the puzzle.

没有人准确的清楚发生了什么，但科学家们至少能拼凑出谜题的一部分答案。

Extinction of course is something that happens not just once, it happens all the time over and over again, I mean,

大灭绝事件其实并不是只有一次而是一直在一次次地发生，

for example, no dinosaur actually lasted more than a couple of million years and all the species went extinct at different times.

比如说就没有哪种恐龙生存超过两百万年，各种物种会在不同的时间灭绝。

The thing about extinction events is that of course they're very bad for the animals that go extinct, but they open up a door of opportunity for a lot of other animals and plants.

说到大灭绝事件，对灭绝的动物当然是一件很糟糕的事，但也为其它的动植物开创了新的生存机遇。

And basically once certain species disappear, than other species will evolve and change and take over their place in that particular ecosystem or habitat.

某些物种一旦消失，其它物种就会进化并且接管前者在生态系统或栖息地的地位。

During the mid-Cretaceous period, the world's environment was changing globally.

白垩纪中叶正值全球环境不断变化的时期。

And these changes can be seen in the fossil plant record.

这些变化可以从植物化石中看到。

Well, dinosaurs like Tenontosaurus and Deinonychus, for whatever reason, were unable to deal with these changes and they were replaced by other dinosaurs that were better suited for the new environment.

像腱龙和恐爪龙这样的恐龙，不管原因如何都无法应对这些改变，最终被其它的能更好地适应新环境的恐龙取代。

Long before recorded time, packs of dinosaurs roamed the Earth, hunting and killing beasts ten times their size.

在有记载之前很久，这些杀手成群徜徉于地球之上猎捕并杀死比它们大十倍的巨兽。

But in this attack, the victim struck back and 115 million years later, the evidence unraveled with modern science lives to tell about it.

但这场战斗中受害者反戈一击，一亿一千五百万年后现代科学下的化石证据还在诉说这一故事。