它们将成为第二大灭绝的鸟类。
They will tum out to be the second-largest species of birds to become extinct.
每一次大灭绝可能都有不同的原因。
在这种假设下，大灭绝的发生是非常突然的。
The mass extinction would have occurred very suddenly under this hypothesis.
许多物种在地质上很短的时间间隔内灭绝的情况称为大灭绝。
Cases in which many species become extinct within a geologically short interval of time are called mass extinctions.
科学家将白垩纪末期的大灭绝与地球上的陨石撞击联系起来。
Scientists have linked the mass extinction at the end of the Cretaceous with a meteorite impact on Earth.
如果你仔细想想，这第六次大灭绝的核心问题是人类的干扰。
If you think about it though, the core problem with this sixth mass extinction is human interference.
随着二叠纪生命形式的衰退，它们达到了一个致命的临界点，物种最终走向了大灭绝。
As Permian life-forms declined, they reached a fatal threshold and species succumbed to mass extinction.
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.
大约2.5亿年前，在地球历史上最严重的一系列大灭绝中，几乎所有的生命物种都消失了。
Roughly 250 million years ago, in the worst series of mass extinction in Earth's history, almost all species of life simply vanished.
在每一次物种大灭绝后，都有一次突然的进化爆发，因为会有新物种出现来填补灭绝创造的生态位。
Following each mass extinction, there is a sudden evolutionary burst as new species develop to fill the ecological niches opened by the event.
地质记录中的其他几次大规模物种灭绝也被认为影响重大，但没有哪一次像白垩纪大灭绝那样夸张。
Several other mass extinctions in the geological record have been tentatively identified with large impacts, but none is so dramatic as the Cretaceous event.
二叠纪大灭绝事件比其他大灭绝事件受到的关注要少得多，因为那时灭绝的大多是我们不熟悉的物种。
The Permian event has attracted much less attention than other mass extinctions because mostly unfamiliar species perished at that time.
今天，我们正在见证第六次物种大灭绝，但与其它几次不同的是，目前生物多样性的丧失可以追溯到人类活动。
Today we are witnessing a sixth mass extinction, but unlike the others, the current loss of bio-diversity can be traced to human activity.
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.
但中生代本身便是以一次大灭绝开始的。
——生物从大灭绝中恢复的能力远强于原先预期。
Life recovered from its worst extinction much faster than previously realised.
这也进一步证明我们正在走向下一次大灭绝的厄运。
This is further evidence that we are well on the way to the next great extinction event.
当然，人类正在引发地球历史上第6次物种大灭绝。
Of course, humanity is currently setting off the sixth mass extinction event in Earth's history.
从化石可以证明，在过去的五次大灭绝中，75%动物物种消失。
Evidence from fossils suggests that in the "Big Five" extinctions, at least 75 percent of all animal species were destroyed.
高过百分之九十海绵类、珊瑚类以及腕足类生物在大灭绝中消失了。
More than 90% of Permiangenera of sponges, corals and brachiopods vanished in the extinction.
科学家们对地球上有史以来最大的二迭纪末大灭绝的原因依然有争议。
Scientists are still debating the cause of the end-Permian extinction, the biggest the Earth has ever known.
嵌入加拿大古代岩石的微粒为引发地球大灭绝的原因提供了新的线索。
Tiny particles embedded in ancient Canadian rocks have provided new clues about what might have triggered Earth's deadliest mass extinction.
化石证据显示，中小型动物比较大型物种更有可能在大灭绝中幸存下来。
Fossil evidence suggests that small and medium sized animals were more likely to survive the mass extinction than larger species.
只有2亿5000万年前史上空前的二叠纪大灭绝盖过这次灭绝。
The die-off was surpassed only by the gargantuan Permian extinction 250 million years ago.
这些大灭绝中最近的一次也是人们最熟悉的一次，终结了恐龙时代。
The most recent of the Big Five is the most familiar one—the cataclysm that ended the Age of Dinosaurs.
大多数人认为是西伯利亚大量的火山活动引起全球变暖导致了大灭绝。
Most believe it was brought on by global warming triggered by massive volcanic activity in Siberia.
然而，有一些研究者认为，大约4.5亿年前的奥陶纪大灭绝是伽马射线爆引起的。
However, some researchers believe that a GRB was responsible for the Ordovician mass extinction approximately 450 million years ago.
地球正在经历他的第六次大灭绝事件，许多物种甚至在我们认知它之前就飞速地消逝了。
Earth is experiencing its sixth mass extinction event, species winking out of existence before we even know them.
Melott有关大灭绝的假想表明“宜居地带”不能只在空间上衡量，还得包括时间。
Melott's hypothesis about mass extinctions shows how habitable zones may be measured not just in space but also in time.
虽然天体撞击的毁灭性不容置疑，但是没有证据表明彗星导致了地球物种周期性的大灭绝。
While there’s little doubt about the destructive power of cosmic impacts, there is no evidence that comets have periodically caused mass extinctions on our planet.
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