Dinosaur’s extinction date reexamined

Those who nostalgically look back on our early school-years of science fairs and baking-soda volcanoes might remember learning a little bit about the abundant and ambiguous theories provided to explain the extinction of the dinosaurs.  Among these theories you may racall the giant, killer asteroid that impacted the Earth.

Until as recently as this February, scientists could only predict that the extinction occurred sometime around 66 million years ago.

“Surprisingly, the fact that our best time estimates for the impact event were only reliable within several thousand years of accuracy didn’t seem to bother anyone,” Paul Renne, professor of geology at University of California at Berkley, recalls.

Renne and his team, however, have finally remedied this problem and removed all ambiguity.  Published in Science, their research proposed a new date for the asteroid impact, setting the event at 66,038,000 years ago.  Although the radioactive argon-argon dating technique used was not a novel technique, through a combination of more thorough, comprehensive and careful experimental design and implementation, the margin for error was narrowed to within the same margin of error as the extinction.

“This makes it difficult to argue that [the asteroid impact] didn’t have to do with the extinctions,” Renne said. The asteroid may not have been the sole cause for the mass extinction, however. “There were clearly some significant changes from terrestrial biota before the impact,” Renne said.

In addition to his recent work on extraterrestrial processes, Renne was awarded in 2005 by the American Geophysical Union for his extensive research into the relationship between volcanism and mass extinctions, including a geological phenomena known as flood basalt.  Flood basalt phenomena occur when large coats of basalt lava  stretch over land or ocean floors after a volcanic eruption.

“A major player among these earlier phenomena may have been flood basalt [events],” Renne mentioned.  The Deccan Traps of Central India were estimated with comparable precision to have occurred within the same timeframe as the asteroid impact.

The next step for geologists is to investigate these volcanic events occurring around the time period.  Renne is currently working on submitting a proposal to the National Science Foundation (NSF) for just this purpose.

Despite the study’s obvious historical implications, Renne concurs that greater understanding of the geological events that contributed to the mass extinction of the dinosaurs and other flora and fauna on Earth may yield benefits to more modern-day concerns.  While the intensity of eruptions occurring today does not compare to that of prehistoric volcanism, instead showing up in isolated events such as the recent eruption of Mount Etna, the study of how past global environmental catastrophes transpired may indicate what warning signs to look for in the future.

“If we can tease out how much role they each play, we can understand the ecological effects of modern [phenomena] in producing major mass extinctions now,” Renne said.