Volcanic activity in modern-day India, not an asteroid, may have killed the dinosaurs, according to a new study.
Tens of thousands of years of lava flow from the Deccan Traps, a volcanic region near Mumbai in present-day India, may have spewed poisonous levels of sulfur and carbon dioxide into the atmosphere and caused the mass extinction through the resulting global warming and ocean acidification, the research suggests.
The findings, presented on Dec. 5 at the annual meeting of the American Geophysical Union, are the latest volley in an ongoing debate over whether an asteroid or volcanism killed off the dinosaurs about 65 million years ago in the mass die-off known as the K-T extinction.
"Our new information calls for a reassessment of what really caused the K-T mass extinction," said Gerta Keller, a geologist at Princeton University who conducted the study.
For several years, Keller has argued that volcanic activity killed the dinosaurs.
But proponents of the Alvarez hypothesis argue that a giant meteorite impact at Chicxulub, Mexico, around 65 million years ago released toxic amounts of dust and gas into the atmosphere, blocking out the sun to cause widespread cooling, choking the dinosaurs and poisoning sea life. The meteorite may impact may also have set off volcanic activity, earthquakes and tsunamis.
The new research "really demonstrates that we have Deccan Traps just before the mass extinction, and that may contribute partially or totally to the mass extinction," said Eric Font, a geologist at the University of Lisbon in Portugal, who was not involved in the research.
The Deccan traps, which are no longer volcanically active.