Bones of Arctic Dinosaurs Show Signs of Hibernation

Dinosaurs may have survived a cataclysmic collision between an asteroid and the Earth 65 million years ago by hibernating, casting doubt on a theory blaming the event for their extinction, a researcher says.

Scientists have speculated in recent years that a huge object from space crashed into Earth with such force that a cloud of dust filled the air, blocking sunlight and killing plants and animals, including dinosaurs.

Other researchers have disputed the theory, arguing that dinosaurs became extinct over a long period, rather than as the result of a calamity.

William Clemens, a University of California paleontologist, said a study of dinosaur bones found in the Arctic suggests the reptiles could have survived the endless night caused by the collision by cutting down on their activities or by going into hibernation.

Bones, Teeth Analyzed

He made his report of the first results of a U.S. Geological Survey analysis of the bones and teeth at the annual meeting of the Geological Society of America in Orlando, Fla.

Clemens said the bones studied “most likely” came from an ancient Arctic freshwater bay that had a mild climate but supported little vegetation during the long, dark winters.

The bones--which were from a species of crested hadrosaur, or duck-billed dinosaur--were found in August, 1984, in a three-foot-thick deposit of fine clay silt with many fragments of twigs, stems and conifer needles, Clemens said.

The professor said a study of the plant materials “shows that the predominant vegetation was broad-leaf deciduous trees, which went bare during the long winter months.

“The finding suggests that the most abundant plant-eating dinosaurs of this region had little if anything to eat during the winter.

“They may have hibernated or, at least, greatly reduced their activity and body temperature during the winter as turtles, crocodiles and other reptiles do today in the northernmost reaches of their ranges.”

Would Have Survived Blackout

Clemens said the evidence of sparse vegetation during dark winters “further strengthens the view that these dinosaurs would have survived a similar blackout caused by an asteroid smashing into the Earth.”

The asteroid theory was proposed in a 1979 paper by Luis W. Alvarez, a Nobel Prize winner in physics; his son, Walter, a geophysicist, and their colleagues at the University of California.

The paper, which is based on soil analysis, suggested an asteroid struck the Earth about 65 million years ago, throwing up a cloud of dust, and perhaps smoke from forest fires, dense enough to block sunlight for a long period.