Date 01-26-91 231 Subj Dinosaurs Wiped out Quickly? MUFONET-BBS Network - Mutual UFO Netwo

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Date: 01-26-91 2:31 From: JOHN KOMAR Subj: Dinosaurs Wiped out Quickly? MUFONET-BBS Network - Mutual UFO Network ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ =START= XMT: 12:02 Wed Dec 05 EXP: 12:00 Wed Dec 12 SCIENTIST SAYS EVIDENCE SHOWS SUPPORT FOR MASS-CATASTROPHE DEMISE OF DINOSAURS SAN FRANCISCO (DEC. 5) UPI - New evidence bolsters the view that dinosaurs and many other life forms suddenly disappeared 65 million years ago after a huge comet or asteroid struck Earth, a leading scientist says. The report, presented Tuesday at the annual meeting of the American Geophysical Union, was sure to rekindle debate on the controversial topic of how the ancient animals abruptly vanished. More than 2,000 papers have been written on the topic since Nobel laureate Luis Alvarez and his son, Walter, first proposed their ''extraterrestial'' theory of dinosaur extinction in 1980. In an overview of the latest findings, Walter Alvarez, a geology professor at the University of California at Berkeley, said research along an ancient sea floor in southern Spain showed a species of single- celled marine plankton, called foramnifera, suddenly became extinct at the end of the Cretaceous period of history. Similarly, he said, University of Washington scientists have found many species of mollusks died out precisely at the end of the Cretaceous period - about 65 million years ago. And, new studies of dinosaur fossils in Montana has shown an extinction pattern ''consistent with a catastrophic extinction,'' rather than a gradual decline, Alvarez said. Studies have shown as many as 75 percent of all life forms on Earth perished at that time, he said. However, University of Colorado researchers recently reported the discovery of two sets of dinosaur fossils in Wyoming that they say are at odds the sudden extinction theory. Robert Bakker and his colleagues said the dinosaurs appear to have lived 1 million years after their species were thought to have died out. ''Every major extinction of dinosaurs occurred in a series of pulses, '' said Bakker, who argues the mass-catastrophe theory of dinosaur extinction ''is simply not true.'' But Alvarez told the 3,000 scientists attending the geology meeting that there is evidence that at least two large extraterrestrial objects struck what is now North America about the time the many life forms died 65 million years ago. One crater, discovered in Iowa, dates to the end of the Cretaceous era. Crystals dating to the same period have been found a similar crater, 100 kilometers in diameter, on Mexico's Yucatan Peninsula. Other scientists believe they have found evidence of a giant asteroid or comet striking Earth at two sites in the Caribbean Sea. Scientists have calculated that an object with a diameter of 6 miles, falling at 12 miles per second, would have the impact of a 70 million megaton bomb. Alvarez cited a recent University of Chicago study that indicates the impact of such a comet-like object would trigger winds up to 300 miles an hours, tidal waves that run for hours, increased global darkness withcold temporatures for months, and acid and toxic chemical rain for years to decades. ''At first, our critics challenged the impact theory by asking how a comet impact could wipe out as many species as the geological record shows,'' Alvarez said. ''Now they are asking how any species could survive.'' =END= ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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