LOS ANGELES -- Scientists still mourning the demise of the dinosaurs 65 million years ago now suspect the behemoths may have succumbed to the sulfurous atmosphere created when an immense asteroid smashed into a region of Central America's Yucatan peninsula uniquely rich in brimstone.


Researchers at the Jet Propulsion Laboratory in Pasadena and the Russian Academy of Sciences in Moscow say the release of sulfur fumes caused by the impact would have been enough to plunge the planet into a global winter lasting decades, shrouding the planet in sulfuric acid clouds like those veiling the planet Venus.


The discovery provides a key piece of evidence in support of the long-standing theory that an impact could have triggered a global catastrophe lasting long enough to cause mass extinctions. The location of the impact itself -- in an area thick with sulfur-bearing rock -- was crucial. Had the asteroid hit almost anywhere else, the scientists suggested, dinosaurs might still be with us.


"Sulfur does rather nasty things when it gets vaporized and shot up into the atmosphere,'' said Kevin Pope, a private research consultant at Geo Eco Arc Research in La Canada, California, who led the international team of researchers. "That is why it was so lethal to the dinosaurs.''


The work results from an unusual collaboration between U.S. experts in exotic planetary atmospheres and a Russian specialist in the dynamics of how impact craters form.


They also analyzed car-sized boulders of impact debris quarried near the crater.


The new evidence, published in the European journal, Earth and Planetary Science Letters, is the latest addition to a long-running scientific controversy over what killed off the exotic creatures that ruled the planet unchallenged for much of Earth's history.