Scientists sifting through ancient sediments laid down just after Earth’s most devastating episode of extinctions may have found minuscule fragments of the massive extraterrestrial object suspected to have caused the catastrophe.
About 250 million years ago, at the end of the Permian period, 95 percent of the species in the oceans and 70 percent of those on land went extinct (SN: 2/1/97, p.
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