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Report Questions Role of Mexican Crater

 Report Questions Role of Mexican Crater

By Associated Press

March 1, 2004, 5:05 PM EST

WASHINGTON -- A Mexican crater often cited as evidence that a single asteroid 
wiped out the dinosaurs may not have been involved in that extinction at all, 
according to a new report. 
A group of researchers led by Gerta Keller of Princeton University contends 
that the impact that caused the crater occurred 300,000 years before the 

In a paper appearing in this week's online edition of Proceedings of the 
National Academy of Sciences, the group cites a layer of sediment it found 
the impact layer and the co-called K-T boundary that marked the mass 
extinction 65 million years ago. 

Because it would have taken hundreds of thousands of years for the limestone 
layer to form, they argue the impact must have occurred well before the