Developments in Brief : Dinosaur Extinction Theory Questioned

Australian scientists examining fossils of what they call “dinosaurs of darkness” are questioning the theory that dinosaurs became extinct after a large comet or meteor hit Earth and plunged it into prolonged darkness.

Recent finds suggest that 110 million years ago, dinosaurs lived in the Antarctic Circle, where they survived sunless winters lasting three to four months, said Tom Rich, curator of vertebrate fossils at the Museum of Victoria in Sydney.

He said the period of darkness would need to have lasted 10 years or more to wipe out the prehistoric reptiles, the predominant species at the time. “The question is whether the Earth was in darkness for a period of years.”

Rich said he is not discounting theories that an atmospheric dust cloud blocked sunlight and killed plants that provided dinosaurs with food. But that cannot be the only cause of the mass extinction, Rich said. “We don’t say it’s fallacious, but the theory needs to be modified or reviewed. We know a few months of darkness couldn’t have knocked them out.”

Other theories that have been advanced to explain what killed the dinosaurs 65 million years ago range from volcanoes to acid rain produced by comet showers.