This break in Earth's history is marked by a mass extinction, when as many as half the species on the planet became extinct.

地球历史上的这次重大灾难以物种的大量消亡为标志；当时，地球上多达一半的物种都灭绝了。

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But the Mesozoic, too, began with a mass extinction.

但中生代本身便是以一次大灭绝开始的。

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In this movie, a comet miles across is headed toward Earth, sure to cause a mass extinction if it hits.

在这部影片里，以颗直径几英里的彗星直奔地球而来，一旦撞上，就会是天崩地裂的大灾难。

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It suggests that the Internet Age is now about to end, with a mass extinction of dot-coms as sweeping and complete as the one of reptiles at the end of the Jurassic.

FORBES: Opportunity Knocking

ABSTRACT:A REPORTER AT LARGE about the sixth mass extinction.

NEWYORKER: The Sixth Extinction?

But, for those of a nervous disposition, the tying of an ancient greenhouse warming to an ancient mass extinction might suggest lessons for the future.

ECONOMIST: A geological burp may have led to the dinosaurs�� domination