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Giant long-necked Sauropods were able to browse at treetop levels, while other plant eating dinosaurs were perfectly adapted to take advantage of the low-growing vegetation.
巨大的长颈蜥脚类恐龙能够吃树顶上的嫩枝，而其它的植食恐龙完美地适应了利用较低处生长的植物。
When you look at Stegosaurus and Camarasaurus, you'd be hard pressed to find two dinosaurs with such different feeding habits.
在观察剑龙和圆顶龙时，你会惊讶地发现这两种恐龙的进食习性迥异。
Camarasaurus feeds high in the trees, where as Stegosaurus was a low browser.
圆顶龙在树的高处进食，而剑龙则在一个低处进食者。
Since both of these dinosaurs went extinct at the end of the Jurassic, then it's safe to suggest that all plants, from the tallest trees to the lowest shrubs,
因为这两种恐龙都在侏罗纪末期走向灭绝，这就很容易推测所有植物，从最高的树木到最低的灌丛，
were affected by some sort of environmental change and if the plants were changing, this would have a huge impact on the plant eaters who relied on them for life.
都受到某种环境变化的影响，而且如果植物在变化，就会对以它们为食的植食者造成巨大影响。
The late Jurassic period also saw predators develop all around the globe, Allosaurus and Ceratosaurus were the deadliest.
晚侏罗纪时期也见证了掠食者在全球的发展，异特龙和角鼻龙是最致命的。
Ceratosaurus was more of a niche predator.
角鼻龙更是一种小生境的掠食者。
It certainly would have had to been specialized on a certain type of behavior with feeding.
它当然必须要有某种专门的进食行为。
It may have fed solely on Sauropods, it may have fished, it may have gone after smaller prey.
它可能只以蜥脚类恐龙为食，它也许以鱼类为食，它可能攻击更小的猎物。
Big animals like Allosaurus and Ceratosaurus are the first to suffer during a dramatic climate change.
像异特龙和角鼻龙这样的大动物在剧烈的气候变化中最先受难。
Because of their sheer size, they require a certain amount of food and a certain amount of water.
因为它们的巨大体型，它们需要一定量的食物和一定量的水。
But just as dinosaurs were beginning their ascent, a massive explosion in deep space would start a countdown to their demise.
不过在恐龙开始渐渐繁盛之时，深远的太空中一次巨大的爆炸开始了它们灭绝的倒计时。
Two giant asteroids collided.
两颗巨大的小行星相撞了。
The larger of the two was called Baptistina.
两颗中较大的那颗被称作巴蒂斯缇娜。
We think it was probably on the order of about a 170 kilometers across.
我们认为它的直径大概有170千米。
And then, something very large slammed into it, we think about 170 million years ago.
后来有个很大的东西撞上了它，我们认为是在一亿七千万年前。
The size of the impactor isn't quite known, but we think it might be on the order of about 60 kilometers or so.
撞击物的大小并不确定，但我们认为大概是60千米（的直径）。
And that completely pulverized we call the Baptistina parent body.
那完全粉碎了巴蒂斯缇娜母体。
The impact between these two celestial missiles caused Baptistina to break up, shooting fragments out of orbit and into the solar system.
这两枚天体导弹的碰撞导致了巴蒂斯缇娜的解体，碎片从其轨道上射出进入了太阳系。
Most of these fragments ended up floating harmlessly in space, but a few headed toward a collision with earth.
这些碎片中的多数在太空中无害地漂浮着，不过有一些却向着地球迎头撞来。
This massive asteroid strike would ultimately wipe out the dinosaurs for good.
这次巨大的小行星撞击最终会让恐龙永远消失。
But strangely, this cataclysm from space was not the first massive disaster that the dinosaurs faced.
但奇怪的是，这来自太空的大灾难并非恐龙们面对的第一次大灾难。
100 million years earlier, the dinosaurs suffered another less complete extinction.
在此一亿年前，恐龙遭受过另一次没那么彻底的灭绝事件。
This first extinction came towards the end of the Jurassic period.
这一次灭绝事件在侏罗纪的末期到来。
It is estimated that 25% of all life forms were wiped out.
据估计所有物种的四分之一消失不见。
When the environment changed at the late Jurassic, it really caused problems for the bigger dinosaurs.
当环境在晚侏罗纪时期发生变化时，真的对较大的恐龙造成了麻烦。
Allosaurus and Ceratosaurus could simply be victims of their inability to adapt to this new environment.
异特龙和角鼻龙可能就因为无法适应新环境而成为牺牲品。
Today, it's still a mystery.
如今，这仍是个迷。
Some believe that they may have been the victims of their own success.
有些人相信它们可能是自己成功的牺牲品。
They seemed to have been driven to extinction by their own success.
它们好像是被自己的成功推向灭绝。
That sounds strange, but once you think about it, a successful dinosaur is one that produces descendants, and in the next time period,
那听起来很奇怪，不过要是仔细想想，一种成功的恐龙就是能产生后代的恐龙，而在接下来的时期，
the early Cretaceous, there are new Allosaurs and new Ceratosaurs in different parts of the world.
在早白垩纪，在世界各地会有新的异特龙和新的角鼻龙。
More sophisticated descendants of each of these forms.
它们都是这些更为复杂的后代。
Things that were too sophisticated for the original Ceratosaurus and the original Allosaurus to compete against.
对原始的角鼻龙和原始的特异龙来说它们太复杂的东西，以至于无法跟它们抗衡。
So as old fashion Ceratosaurus and old fashion Allosaurus themselves, they both disappeared.
所以老式的角鼻龙和异特龙自己就都消失不见了。
But in every major extinction, no matter how catastrophic, there are always some survivors.
不过每次大规模灭绝中，无论灾难性多大，总有一些幸存者。
And for those plants and animals that are able to adapt quickly enough, the world is theirs for the taking.
而对那些能够很快地适应的植物和动物来说，世界就是它们的了。
It's easy to think that all dinosaurs lived and died at the same time, but that's not the case.
人们很容易认为所有恐龙都在同一时期生活和消亡，但并非如此。
For instance, dinosaurs like Stegosaurus, Allosaurus, and Camarasaurus lived in the Jurassic Period and died out tens of millions of years before dinosaurs like Tyrannosaurus Rex showed up.
比如，生活在侏罗纪时期的恐龙，像剑龙、异特龙和圆顶龙，消失于像雷克斯暴龙这样的恐龙出现数千万年前之前。
In fact, the time that separates those dinosaurs from T-Rex is longer than the amount of time that separates T-Rex from us.
其实，那些恐龙和霸王龙间的时间间隔要比霸王龙和我们之间的间隔还要长。
