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.
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.
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.
根据自然资源保护者的重要回顾报告，地球正经历“第六次大灭绝事件”，因为疾病和人类活动正在令脆弱的物种遭受到灾难性打击。
Earth is experiencing its "sixth great extinction event" with disease and human activity taking a devastating toll on vulnerable species, according to a major review by conservationists.
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.
据认为，那次古老冲撞的碎片在六千五百万年前曾经撞击地球，引发了消灭恐龙的大灭绝。
One fragment of that ancient smash is thought to have struck Earth 65 million years ago, triggering a mass extinction that wiped out the dinosaurs.
相反，栖息地的破坏继续有增无减，一些专家警告说，地球现正面临其第六次大灭绝阶段-自6500万年前恐龙消失最新的一次。
Instead, habitat destruction has continued unabated, and some experts now warn that the planet faces its sixth mass extinction phase — the latest since dinosaurs vanished 65 million years ago.
美国自然历史博物馆脊椎古生物学家Jack Conrad解释说，k - T大灭绝之后，不但哺乳动物开始主宰地球，鲨鱼也开始在海洋中扩张。
Not only did mammals sweep across the planet after K-T, but sharks expanded across the seas, explained American Museum of Natural History vertebrate paleontologist Jack Conrad.
闯入地球的小行星一般被认为是白垩-第三纪灭绝，即恐龙遭受大灭绝的主要原因之一。 那次毁灭性事件灭绝了地球上超过一半的物种，为哺乳动物成为地球上的首要物种扫清了道路。
The extinction was caused by a massive asteroid slamming into Earth at Chicxulub in Mexico.
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.
作为世界上第三大热门的沙漠，戈壁拥有数个地球上最大的沙丘以及独一无二的野生动物象濒临灭绝的戈壁熊。
The world's third largest "hot" desert, the Gobi is home to some of Earth's largest dunes, as well as unique wildlife like the endangered Gobi bear.
到目前为止，古生物学家认为恢复需要几千万年的时间——原因要么是由于大灭绝的深重影响，要么是由于火山爆发导致地球变成有毒的荒漠。
Until now, paleontologists have thought the recovery took tens of millions of years-a reflection either of the profundity of the Great Dying or of the toxic desert planet that the eruptions created.
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.
澳大利亚科学家担心，随着海洋死区范围和数量不断加大，地球已到了另一次大灭绝的边缘。
Australian scientists fear the planet is on the brink of another mass extinction as ocean dead zones continue to grow in size and number.
作为地球史上消亡物种排行第三的大灭绝，奥陶系-志留纪大灭绝有两个死亡高峰期，其中相隔数十万年时间。
The third largest extinction in Earth's history, the Ordovician-Silurian mass extinction had two peak dying times separated by hundreds of thousands of years.
令人放心的研究结果表明，天文学家已经掌握了90％以上大型的小行星的空间位置，它们是一些可能导致地球表面生物物种大灭绝的，巨大的杀手行星。
The study reassuringly suggests that astronomers already know the location of more than 90 percent of the very largest asteroids — the huge planet-busters that could cause mass extinctions.
铱：如果铱听起来让你觉得熟悉，那可能是因为很多通讯卫星都是以这种硬而脆的大密度金属元素命名的，也可能是因为恐龙在白垩纪末从地球灭绝，与铱有关的缘故。
Iridium (Ir): If iridium sounds familiar, that might be because there’s a group of communications satellites named after this element, a hard, brittle and dense metal.
科学家称，地球上的生命每隔2700万年就会被灭绝一次，我们到下一次大灭绝之前还有约1600万年时间。
Life on Earth is wiped out every 27 million years -and we have about 16 million years left until the next extinction, according to scientists.
Andean - Saharan冰河期横跨了Ordovician冰河期的后期和Silurian冰河期的前期，大灭绝成为了其标志性事件，那是地球历史上第二个气候最恶劣的时期。
Straddling the late Ordovician period and the early Silurian period, the Andean-Saharan ice age was marked by a mass extinction, the second most severe in Earth's history.
从另一个角度看，“巧妙之处在于，大灭绝事件就像重启按钮，通过它可以改变主宰地球的物种，”Conrad说。
Otherwise, "one neat thing about mass extinction events is that they're often reset buttons, where you change what dominates the globe, " Conrad said.
上一次大灭绝事件是在1100万年前发生的，当时地球上10%的居住者遭到灭绝。
The last extinction event, 11 million years ago, saw 10 per cent of the Earth’s inhabitants wiped out.
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.
比如，白垩纪至第三纪所发生的大灭绝。当时，可能由于一颗小行星撞击地球，恐龙和众多同时代的物种都灭绝了。
An example is the KT Mass Extinction when the last dinosaur and ammonite species, among others, became extinct, perhaps as a result of an asteroid striking the Earth.
当大规模的流星淋浴威胁着地球上的生物大灭绝级别的事件，是世界上最伟大的头脑想出一个危险的计划，将采取关闭星球的轴线，以避免撞击。
When a shower of massive meteors threatens an extinction level event on Earth, the world's greatest minds devise a dangerous plan that will take the planet off its axis in order to avoid the impact.
科学家研究了过去5亿年间地球上发生的所谓的“灭绝事件”，时间跨度是先前任何一项研究的两倍。此次研究证实大灭绝的出现是有时间规律的。
Research into so-called 'extinction events' for our planet over the past 500 million years - twice as long as any previous studies - has proved that they crop up with metronomic regularity.
地球的第六次物种大灭绝正在上演。一项新的研究发现，人类是其背后的推动力。
Earth's sixth mass extinction is already underway - and humans are the driving force behind it, according to a new study.
地球的第六次物种大灭绝正在上演。一项新的研究发现，人类是其背后的推动力。
Earth's sixth mass extinction is already underway - and humans are the driving force behind it, according to a new study.
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