Gases resembling modern air pollution may have killed off the dinosaurs, according to findings announced by international researchers Sunday at a scientific conference.
It has long been thought that dust and debris thrown up when a 16-kilometer (10-mile) wide meteor struck a shallow sea 65 million years ago created a giant particle cloud around the earth, cutting off sunlight and killing the dinosaurs.
Such a collision is believed to have created the 200 kilometer (125-mile) wide Chixulub crater on Mexico's Yucatan Peninsula.
Recent computer and field studies, in fact, indicate that the collision 65 million years ago may not have been powerful enough to drive debris skyward to shroud the planet for long enough to kill off life.
Scientists presented findings at a American Geophysical Union gathering here, to indicate that mineral dust from the impact reacted with the earth's atmosphere, creating a deadly sulfuric acid and carbon dioxide mist.
"It had to be some kind of atmospheric chemistry," concluded Virgil Sharpton, a researcher with the University of Alaska. "That's the only way the impact would have had a global reach."
In June, scientists will drill 2.4 kilometers (1.5 miles) into the crater to find further samples to test their theory -- SAN FRANCISCO (AFP)
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