恐龙研究专家认为，现代鸟类直接起源于手盗龙类，其他已灭绝的恐龙现在被称之为“非鸟恐龙”。
Modern birds are direct descendants of Maniraptoran dinosaurs, experts say. The creatures that went extinct millions of years ago are now called "non-avian dinosaurs."
例如，如果没有恐龙的灭绝，我们这些哺乳动物就不会有机会繁荣昌盛。
For instance, if it hadn't been for the extinction of the dinosaurs, we mammals would never have had an opportunity to flourish.
也许恐龙无法忍受这些极端的温度变化于是灭绝了。
Perhaps dinosaurs could not tolerate these extreme temperature changes and became extinct.
化石记录表明，在地球有动物居住的所有时期，已经有五次大灭绝发生，恐龙是最近的一次。
The fossil record indicates that in all the time that animals have inhabited Earth, there have been five great mass extinctions, dinosaurs being the most recent.
人们对恐龙灭绝的传统解释感到不满，导致了一个令人惊讶的发现，转而引发了新的假设。
Dissatisfaction with conventional explanations for dinosaur extinctions led to a surprising observation that, in turn, has suggested a new hypothesis.
一些科学家假定，小行星撞击地球导致了恐龙的灭绝。
Some scientists hypothesize that the extinction of the dinosaurs resulted from the effects of an asteroid collision with Earth.
据推测，这些环境灾难可能是物种大规模灭绝的成因，包括恐龙的灭绝。
Presumably, those environmental disasters could have been responsible for the mass extinction, including the death of the dinosaurs.
不管什么原因，恐龙以及地球上几乎半数以上的物种灭绝了。
Whatever the cause, dinosaurs, as well as about half of all species on the planet, went extinct.
在此之前，气候的变化导致了海平面的剧烈波动，恐龙因此灭绝。
Changes in climate before that period caused severe fluctuation in sea level, resulting in the extinction of the dinosaurs.
人们提出了许多关于恐龙灭绝的理论，但大多数都是不成立的。
Many theories have been put forward for the extinction of the dinosaurs, but most of them can be dismissed.
虽然在地质记录中有十几次甚至更多的大灭绝，但白垩纪的大灭绝总是引起古生物学家的兴趣，因为它标志着恐龙时代的结束。
While there are a dozen or more mass extinctions in the geological record, the Cretaceous mass extinction has always intrigued paleontologists because it marks the end of the age of the dinosaurs.
白垩纪以前的气候变化导致了海平面的剧烈波动，引发了恐龙的灭绝。
Changes in climate before the Cretaceous period caused severe fluctuation in sea level, resulting in the extinction of the dinosaurs.
在这一系列周期性物种灭绝事件里，白垩纪晚期恐龙和菊石的灭绝仅仅是其中一个比较严重的事件。
The late Cretaceous extinction of the dinosaurs and ammonoids was just one of the more drastic in a whole series of such recurrent extinction episodes.
一些天文学家认为他们可以看到更多的恐龙与宇宙之间的联系，这种大规模灭绝的模式就像地质记录上的时钟一样。
A few astronomers thought they could see even more of a dinosaur-cosmos link, a pattern of mass extinctions occurring like clockwork in the geologic record.
作者说，行星的影响和恐龙的灭绝可能不是发生在同一时期，而是在大约300 000年前分别发生的。
The asteroid impact and dinosaur extinction, say the authors, may not have been simultaneous, instead occurring 300, 000 years apart.
随着其他大型恐龙的灭绝，使得Raptorex有机会将体型进化成硕大型，最终成为巨大的霸王龙。
As other large dinosaurs became extinct, this left the path clear for Raptorex to expand in body size and ultimately become the giant Tyrannosaurus rex.
那么，既然可能是陨星造成了恐龙的灭绝，今天的我们是否应该对天空心存惧意？
So, if a meteor helped to wipe out the dinosaurs, does this mean we should be terrified of the skies today?
曾经称霸地球显赫一时的恐龙，在白垩纪时代的这次温度巨变中，似乎全都灭绝了。
The temperature drop during the Cretaceous period would almost certainly have wiped out an 'abundance' of the world's dinosaurs.
小行星为恐龙的灭绝“负责”这一说法毕竟留下了比希克苏鲁伯的陨石坑更多的证据。
The asteroid charged with killing the dinosaurs, after all, left more than the Chicxulub crater as its calling card.
约有20%的海生群落以及多数类似哺乳类的生物，很多大型的两栖动物，和所有的非恐龙的祖龙都灭绝了。
About 20 percent of all Marine families went extinct, as well as most mammal-like creatures, many large amphibians, and all non-dinosaur archosaurs.
相对立的观点则认为哺乳类和鸟类在恐龙灭绝之后才成功并演化为各种不同的物种。
The opposing view is that mammals and birds did not become successful and radiate into many different species until after the demise of the dinosaurs.
自然界将前五次灭绝带给了恐龙和地球上的其它居民，它们以冰河、陨星或火山的形式到来。
The previous five extinctions were visited upon the dinosaurs and other denizens of the earth by the natural world, coming as glaciers, meteorites, or volcanoes.
无论如何，尽管恐龙没有留下可用的DNA，其他更晚灭绝的生物却更加慷慨。
In any case, though dinosaurs have left no usable DNA, other more recently departed creatures have been more generous.
牙形刺在三叠纪末期灭绝了，这正是恐龙开始演化的时代。
Conodonts went extinct at the end of the Triassic Period, about the time dinosaurs were evolving.
他举了一个非常有说服力的例子——他指出在离孟买海岸不远处有一座名为“孟买高山”的水下山恰好是在恐龙灭绝的时候形成的。
He makes a compelling case, identifying an underwater mountain called Bombay High, off the coast of Mumbai, that formed right at the time of the dinosaur extinction.
科学家知道体型庞大的哺乳类们在恐龙灭绝后的几百万年就进化了出来。
Scientists knew that extremely large mammals evolved within a few million years after the end of the dinosaurs.
恐龙的灭绝很可能是由于一颗巨大的流星导致地球温度降到了它们生存的临界值以下。
Dinosaurs were most likely wiped out by a giant meteor that cooled Earth's temperatures below their threshold for survival.
许多科学家认为，地球遭受小行星或彗星的直接撞击可能是恐龙灭绝的原因。
Many scientists believe the Earth suffered a direct hit from an asteroid or that a comet could be to blame for the extinction.
许多科学家认为，地球遭受小行星或彗星的直接撞击可能是恐龙灭绝的原因。
Many scientists believe the Earth suffered a direct hit from an asteroid or that a comet could be to blame for the extinction.
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