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Did hurricanes blow dinosaurs away?

Pity the poor dinosaurs. Though the immense saurians and many of their neighbors disappeared from the planet 65 million years ago, scientists never tire of dreaming up ways to kill off the beasts.

The newest theory, proposed by Massachusetts Institute of Technology atmospheric scientist Kerry A. Emanuel and his colleagues, revolves around monster hurricanes called hypercanes. While studying factors that limit hurricane size, Emanuel recognized that tropical storms could, in theory, grow much larger than they do at present if ocean water warmed to 50oC, almost double current temperatures in the tropics. Ocean water does not get that warm under normal conditions, but a large meteorite impact into the ocean or a major volcanic eruption in shallow water could drive temperatures into the hypercane zone, according to simulations done with a computer model of the atmosphere, the scientists report in the July 20 Journal of Geophysical Research.

Therein lies the dinosaur connection. Emerging evidence suggests that a large extraterrestrial body hit the Gulf of Mexico at the end of the Cretaceous period, about the same time as the mass extinction recorded in the fossil record. The crash could have warmed water enough to spark a series of hypercanes that reached altitudes of 45 kilometers, well up into the stratosphere. Normal hurricanes top out at the base of the stratosphere, about 19 kilometers up.

Because of their height, the storms could have transported water vapor, ice particles, and dust into the stratosphere, where they would block out sunlight and decimate the life-protecting ozone layer, speculate the researchers. "The idea is a little far-fetched," admits Emanuel. "But I don't think it's so far-fetched as to be outrageously unlikely."
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Title Annotation:Earth Science; "hypercanes" may have caused mass extinction at end of the Cretaceous period
Publication:Science News
Article Type:Brief Article
Date:Sep 23, 1995
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