Meteorite not responsible for dinosaurs' extinction

20 November 2004 | 12:02 Code : 4491 Geoscience events
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A study conducted by researchers from the University of Princeton has revealed that dinosaurs that roamed the Earth some millions of years before mankind's evolution on this watery planet, ...
A study conducted by researchers from the University of Princeton has revealed that dinosaurs that roamed the Earth some millions of years before mankind's evolution on this watery planet, did not get extinct due to the great meteorite impact earlier believed to be the sole cause of their extinction. According to ABC online, geologists carrying on excavations at the Chicxulub crater have claimed that dinosaurs suffered in two stages rather than one catastrophic impact at Chicxulub crater, the latter according to the experts having taken place nearly hundreds or thousands of years too early for their extinction, as much as 300,000 years before the mass die-off.
The latest study presented at the annual meeting of the Geological Society of America, in effect completely pours water over the previous theory that the meteorite impact at the crater was the "smoking gun" for the annihilation of nearly 70% of living species at the Cretaceous-Tertiary (or the K-T) boundary, 65 million years ago.
Excavations at Yaxcopoil 1 a borehole expected to provide final irrefutable confirmation of Chicxulub's role in the K-T boundary mass extinction didn't reveal anything substantial.
Studies revealed that the layers of rocks at Yaxcopoil 1 borehole were stacked like old newspapers, rather than the one found at Chicxulub impact site, which were interspersed with broken "breccia" rocks. More over the iridium signal, the extraterrestrial element that first gave scientists clue on the involvement of asteroid for the K-T extinction was also found missing from the Yaxocopil 1 borehole site.
"Breccia is about 60 centimetres of gently-laid-down, thinly layered seafloor mud built up over 300,000 years. Those 60 centimetres of ho-hum, post-impact mud have the fossils, carbon isotopes and magnetic signal of the late Cretaceous, before the mass die-off. It's not until 300,000 years later, and about 60 centimetres higher, that a sharp change in carbon isotopes and changes in microfossils signal the massive K-T extinction event," Keller was quoted as saying.
Keller presently is of the opinion that the reason for the dinosaurs' extinction was the asteroid impact combined with intense volcanic activity.
"What Gerta Keller is showing us is that there is reason to doubt.[The smoking gun] can't be even a 100 years older than the K-T boundary. There is room for inquiry here," said Dr Spencer Lucas, curator of palaeontology and geology at the New Mexico Museum of Natural History and Science Lucas he added.

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