Once, Lives on Earth are reshuffled by extinction events, but the evolution never stops.
曾经，地球上的生命因遭遇灭绝而重新洗牌，但演化从未停下脚步。
There have been five planetary extinction events in the last half-billion years. The sixth is happening now.
在过去几千万年漫长岁月中，曾经有五个行星消失，现在第六个行星的消失正在发生。
In previous extinction events it took hundreds of thousands to millions of years for the planet to re-diversify.
在以前的大规模灭绝之后，地球要花上几十万到几百万年的时间才能重新实现物种多样化。
Otherwise, "one neat thing about mass extinction events is that they're often reset buttons, where you change what dominates the globe, " Conrad said.
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。
Some scientists think that massive ocean extinction events in the past caused Earth's carbon cycle to fluctuate wildly for millions of years afterwards.
一些科学家认为过去大量海洋生物的灭绝，将引起数百万年后地球碳循环上下幅度变大。
However, the invasion of the so-called elpistostegalians—distant relatives of the coelacanth—"got wiped out by these extinction events, " McGhee explained.
但是，腔棘鱼的远亲elpistostegalians（译注：大概是一种爬上陆地的古鱼，没找到对应的中文）向陆地进发的努力“被这次大灭绝毁于一旦，”McGhee 解释说。
Even if the scientific consensus is that extinction events don't occur in a predictable cycle, there are now other reasons to suspect a dark companion to the Sun.
即使在“物种大灭绝事件不会在一个可预测的周期中发生”这一观点上达成科学共识，我们也没有理由去怀疑太阳有一颗黑暗的伴星。
The earliest of the Big Five, the end-Ordovician or Ordovician-Silurian extinction events some 444 million years ago, are reckoned by many to be the second largest.
五次大灭绝中发生最早的一次是奥陶纪末期或者奥陶纪-志留纪大灭绝事件，发生在大约4亿4千4百万年前。许多科学家估计这次规模是五次当中第二大的。
But research is uncovering how these extinction events dictated the fate of life on this planet-for instance, determining which animals first crawled onto land and which ruled the oceans.
但是，科学研究正在揭示这几次大灭绝如何改变地球生物的命运——比如，决定了首先出现在陆地的动物和统治海洋的生物。
Although the four other Big Five extinction events led to huge changes in which animals rose to prominence, the same animals that dominated before the end-Ordovician dominated afterward.
其它四次大灭绝对生物进化产生了巨大的影响，动物因此逐渐处于优势地位，但是，奥陶纪末期大灭绝发生前后，处于支配地位的动物物种没有发生变化。
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.
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。
Now the closest look yet at events 252 million years ago is linking those eruptions even more closely not only to the biotic cataclysm in the sea but also to the mass extinction on land.
目前对这个2.52亿年前发生的大事件的深入研究表明，这次爆发不但导致了海底生物的灭绝，连陆地上的生物亦难免于难。
However, unlike the five before this, this extinction is caused not by natural events, but by humans.
与前五个大绝种时期最大的不同是，这次并非自然现象，而是来自人为。
However, unlike the five before this, this extinction is caused not by natural events, but by humans.
与前五个大绝种时期最大的不同是，这次并非自然现象，而是来自人为。
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