News Focus

Mammoth-Killer Impact Flunks Out

Science  03 Sep 2010:
Vol. 329, Issue 5996, pp. 1140-1141
DOI: 10.1126/science.329.5996.1140

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Summary

Did a continent-searing comet impact wipe out the mammoths and other great beasts? Impact specialists have now weighed in on that widely publicized possibility. Their verdict: There never was a mammoth-killer impact. Proponents' evidence "is not internally consistent, not reproducible, and certainly not consistent with being produced by impact," says a geochemist who has been publishing on impacts for 27 years. Since impact specialists went looking on their own, he says, "nobody has found anything." The final blow, in the eyes of some, comes this week in a paper reporting a failure to find proponents' most promising trace of an impact, a particular crystal form of nano-size diamond. But core supporters of the impact scenario are sticking to their guns.