In their search for the cause of the mass extinction at the end of the dinosaur age, geologists already had a smoking gun: a 180-kilometer impact crater on the Yucatan Peninsula. Now they may have a piece of the bullet. At last week's Lunar and Planetary Science meeting in Houston, geochemist Frank Kyte of the University of California, Los Angeles (UCLA), flashed slides of a chip of rock that he thinks may be a tiny fragment of the 10-kilometer object that blasted Earth 65 million years ago. From theage and makeup of the 3-millimeter chip, found in the ooze at the bottom of the North Pacific, Kyte is "personally convinced that it is a piece of the bolide," a conclusion other researchers say is at least plausible. "What all the implications are, I'mstill trying to figure out," he adds. "The unfortunate thing is that it's mainly mud and rust" after sitting in Pacific sea-floor sediments for 65 million years. But it is already offering some clues to the nature of the catastrophe. A first look at therock chip's makeup implies the fatal object was an asteroid, not a comet, as some researchers have speculated, and its survival supports an earlier suggestion that the parent body struck Earth at a shallow angle--which may have been the crudest possibleblow.
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