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Radiation in the clear over dinosaur deaths

点击量:   时间:2017-11-06 01:02:03

We can scratch a couple of suspects from the list of possible dinosaur killers. Too few dinosaur fossils show evidence of bone cancer to conclude that a lethal dose of ionising radiation did them in – or that they took up smoking, as Gary Larson once whimsically suggested in a Far Side cartoon. Adrian Melott, an astrobiologist at the University of Kansas in Lawrence, has suggested that periodic overdoses of cosmic rays or bursts of gamma rays might have caused mass extinctions. Past periods of heavy radiation leave little direct trace,