Was there a Stone Age apocalypse or not? One theory has it that about 13,000 years ago a comet blasted North America, wiping out the continent's megafauna -as well as its early settlers.rnIt's a compelling story that offers a simple explanation to the mystery of why mammoths, mastodons, and Clovis humans disappeared. But it's highlyrncontroversial, and new research suggests the impact was far too small to have done any serious damage.rnDoubts spring from the speed of extinctions, the fate of the Clovis culture and the presence, or lack, of supposed impact signatures. Advocates of the comet-blast theory say they will present new data at the American Geophysical Union (AGU) meeting in San Francisco, where they will share the stage with sceptics.
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