[NetBehaviour] Microfossil Data Show Yucatan Impact Did Not Wipe out Dinosaurs.
marc.garrett at furtherfield.org
Mon Jan 29 17:23:59 CET 2007
Microfossil Data Show Yucatan Impact Did Not Wipe out Dinosaurs.
Recent microfossil evidence casts fresh doubt as to whether an asteroid
wiped out the dinosaurs, according to micropaleontologist Gerta Keller
of Princeton University in Princeton, N.J., and her collaborators. Their
analysis of ancient marine-dwelling microorganisms, called foraminifera,
suggests that global warming caused by massive volcanism in India “led
to dwarfing of all species and a gradual decrease in their diversity
beginning 400,000 years prior to the mass extinction,” she says.
This analysis challenges a hypothesis formulated more than 25 years ago
by geologist Walter Alvarez of the University of California, Berkeley,
his father Luis, a physicist who had won the Nobel Prize, and their
collaborators. They argued that a catastrophic cosmic event, often
called the Chicxulub impact, on the northern Yucatan Peninsula of Mexico
led to the demise of the dinosaurs. They traced that impact to the
Cretaceous Tertiary (KT) boundary period 65.5 million years ago and
claimed it caused extinction of 60% of all life on Earth from dinosaurs
to microscopic marine organisms such as the foraminifera.
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