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Asteroid Extinction Event Also Killed Many Early Snake And Lizard Species

December 11, 2012
Image Caption: In the foreground, the carnivorous lizard Palaeosaniwa stalks a pair of hatchling Edmontosaurus as the snake Cerberophis and the lizard Obamadon look on. In the background, an encounter between T. rex and Triceratops. (Artwork by Carl Buell)

Lee Rannals for redOrbit.com – Your Universe Online

Despite the name, a new species of lizard reported about in the scientific journal Proceedings of the National Academy of Sciences is not related to our President, because it went extinct when the giant asteroid hit Earth millions of years ago.

Obamadon gracilis was one of the lizard species that suffered from the asteroid event that ended the reign of the dinosaurs 65.5 million years ago.

Previous studies suggested that some snake and lizard species became extinct after the asteroid struck the Earth, but new research argues that the impact was more serious for snakes and lizards than previous thought. Researchers from Yale and Harvard suggest that the bigger the species, the better the chances of extinction.

“The asteroid event is typically thought of as affecting the dinosaurs primarily,” said Nicholas R. Longrich, a postdoctoral associate with Yale’s Department of Geology and Geophysics and lead author of the study. “But it basically cut this broad swath across the entire ecosystem, taking out everything. Snakes and lizards were hit extremely hard.”

The research is based on results of a detailed examination of previously collected snake and lizard fossils in western North America. The scientists examined 21 previously known species, and also identified nine new lizards and snakes.

They found a range of reptile species lived in the last days of the dinosaurs, some of which fed on the eggs of young dinosaur species.

“Lizards and snakes rivaled the dinosaurs in terms of diversity, making it just as much an ‘Age of Lizards’ as an ‘Age of Dinosaurs,’” Longrich said.

Scientists conducted an analysis of the relationships of these reptiles, including many archaic lizard and snake families that disappeared at the end of the Cretaceous period.

While reassessing previously collected fossils, the team came across an unnamed species of lizard and called it Obamadon gracilis.

The Obamadon measured less than one foot long and most likely ate insects, according to the researchers. Although naming an extinct lizard species after a president in an election year could have some form of hidden meaning, the researchers said they were “just having fun with taxonomy.”

The researchers said extinction of snakes and lizards helped pave the way for evolution and diversification of the survivors, by eliminating competitors. There are about 9,000 species of lizards and snakes alive today.

“They didn’t win because they were better adapted, they basically won by default, because all their competitors were eliminated,” Longrich said.

Bhart-Anjan S. Bhullar, a doctoral student in organismic and evolutionary biology at Harvard University and co-author of the paper, said an important innovation in the work was the ability to reconstruct the relationships of extinct reptiles from very fragmentary jaw material.

“This had tacitly been thought impossible for creatures other than mammals,” Bhullar said. “Our study then becomes the pilot for a wave of inquiry using neglected fossils and underscores the importance of museums like the Yale Peabody as archives of primary data on evolution – data that yield richer insights with each new era of scientific investigation.”


Source: Lee Rannals for redOrbit.com - Your Universe Online



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