According to Princeton University paleontologist Gerta Keller and her collaborators Thierry Adatte from the University of Neuchatel, Switzerland, and Zsolt Berner and Doris Stueben from Karlsruhe University in Germany the Chicxulub impact may have been the lesser and earlier of a series of impacts, massive volcanism in India, and climate changes that culminated in the end of the Cretaceous Period.

A still unidentified impact 65.5 million years ago appears to have been the last straw, exterminating two thirds of all species in one of the largest mass extinction events in the history of life. If so its that impact and not Chicxulub which left the iridium layer found in rocks worldwide that marks the impact that led to the final extinction of the dinosaurs, Keller said that the Chicxulub impact predates the mass extinction 300.000 years and left small marine animal microfossils were left virtually unscathed.

`The Deccan volcanism as well as with climate change did the nudging by releasing vast amount of greenhouse gases into the atmosphere over a period of more than a million years leading up tothe mass extinction. By the time Chicxulub struck, the oceans were already 3-4 degrees warmer, even at the bottom, on land it must have been 7-8 degrees warmer` Keller said.

The ghost crater that created the iridium layer may have hit in India, where a crater of about 500 kilometers in diameter is estimated and named Shiva by paleontologist Sankar Chatterjee from the Museum of Texas Tech University in Lubbock. The evidence for it, however, is not very compelling at this time.\\\\\\\"

Keller is scheduled to present that evidence at the Annual Meeting of the Geological Society of America in Philadelphia, 22-25 October. The results of her research, which was funded by the National Science Foundation, will be discussed in two technical sessions and a public lecture sponsored by the Philadelphia Geological Survey.

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