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Mystery Undersea Extinction Cycle Discovered


  • Aug 22 2010 3:34 PM

    MaryRose Lovgren

    This resource was matched by a member of the Brokers of Expertise Standards Matching Team.

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In this National Geographic News article, read about the discovery that the number of marine-animal species rises and falls every 62 million years. Scientists haven't nailed down a cause yet, but comet impacts could play a role. Links to related stories and Web sites are also found on this page.

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