Bones of Contention : Dinosaur Fossils Above Arctic Circle Add Fuel to Debate
A “rich bed” of dinosaur bones has been found north of the Arctic Circle by a team of scientists from the University of California, Berkeley, and the University of Alaska, adding fresh fuel to the debate over the theory that dinosaurs were pushed to extinction by a massive bombardment of the Earth by asteroids or comets.
The bones, found on the northernmost edge of Alaska, prove that some dinosaurs were able to withstand long periods of cold and darkness because they survived in an area where the winter nights are two to three months long.
Suggesting of Discovery
According to UC Berkeley paleontologist William Clemens, the discovery offers a serious challenge to the theory that the reign of the dinosaur ended because comets or asteroids struck the Earth, kicking up clouds of dust that plunged the world into a period of darkness for several weeks, wiping out the food supply.
“Our discovery suggests at least some dinosaurs were able to deal with several months of darkness,” Clemens said in a telephone interview from the University of Alaska, Fairbanks.
If they could routinely survive the long winter nights at that latitude, which had a temperate climate at that time, why would they have been wiped out by sudden darkness brought on by extraterrestrial bombardment?
“I wish I had a good answer for that,” answered Richard Muller, a UC Berkeley physicist and one of the leading proponents of the bombardment theory.
“Obviously, there were some dinosaurs that were adapted to cold and darkness,” said Muller, who insists that the Alaskan discovery does not discredit the widely held belief that the age of the dinosaur ended after a period of intense bombardment from space. He said a catastrophic bombardment of the Earth would do far more than make the world dark and cold.
“We expect there might have been a substantial impact from acid rain, there is the possibility of earthquakes and volcanic activity, and the pollution of the food supply” resulting from the bombardment, he said.
Muller was chief scientist on a project last year that produced evidence showing that “periodic mass extinctions” have coincided with large comets hitting the Earth. That evidence supports a theory advanced by Luis Alvarez, a Nobel laureate, and his son, Walter Alvarez, a Berkeley geologist, who have contended that dinosaurs died from hunger and cold resulting from the dust released into the atmosphere by the impact, thus obscuring the sun.
Faith in Evidence
Muller said the patterns of extinction of various species, coupled with the evidence of celestial bombardment, are so conclusive that the work of Alvarez should be labeled a “discovery, not a theory.”
“They found the body,” Muller said, referring to worldwide evidence that links extinctions with massive meteor showers. “When you find the body, that’s pretty good evidence that a murder occurred. Nobody has offered any alternative hypothesis that has held up.”
Clemens and his colleagues contend, however, that their work now casts doubt on the Alvarez “discovery.”
“The bottom line is the North Slope discoveries add a new dimension to our understanding of the biology of these extinct animals,” Clemens said, noting that the bones found in Alaska show the dinosaurs could withstand both cold and darkness for considerable periods.
“You can’t just knock the dinosaurs off by putting them in the dark,” added Carol Allison, a paleontologist from the University of Alaska and a member of the team.
The team found bones from at least five species of dinosaurs in the Alaskan tundra near Prudhoe Bay “west of Deadhorse,” Clemens said. The dinosaurs roamed that area at least 65 million to 70 million years ago, he said, when the polar region had a temperate climate. The area where the bones were found would have been at least as far north as it is today, well above the Arctic Circle, he added.
Adaptation to Darkness
At that latitude, “the sun goes down in November and doesn’t come up until February,” said Allison, who is also the curator of the paleontology museum at the Fairbanks campus.
“This suggests that there was some adaptation to the darkness” by the dinosaurs, Allison said.
“They might have entered into a period of torpor with a low metabolic rate,” she suggested. Under those conditions, the dinosaurs “would not have a high food requirement.”
The most common bones found at the site are of duck-billed dinosaurs known as hadrosaurs, plant-eating reptiles that stood 12 to 15 feet high. Scientists also discovered two kinds of carnivorous dinosaurs and parts of an aquatic reptile, indicating that the site was near an ancient swamp, Clemens said.
Signs of dinosaurs have been found in the area over the years, but the first bones were dug out of the tundra in 1961 by an oil company geologist. That discovery was not made public until last year, when the U.S. Geological Survey decided to finance an expedition.
Although the bones found this summer were not surprising, the size of the find was, Clemens said.
“We went up there knowing we would find something,” he said. “But I’m intrigued by the abundance at this site. It is one of the richest bone beds that I’ve ever seen.”
The team lived in tents at the site for 10 days. The exact location is being kept secret because of fears of vandalism even in that remote area, Clemens said.
Although Clemens and his colleagues hope the find will enrich the understanding of the age of the dinosaur, some scientists, including Muller, doubt that it will end the debate over what caused them to die out.
“People who look at the pattern of extinctions have a difficult job because of the complexities of life, the fragility of life, and the robustness of life,” Muller said. “Some creatures can adapt and others can’t.”
Without finishing his thought, he wondered aloud, “So when you are trying to look back, and ask how come they (dinosaurs) went out and many of the mammals didn’t. . . .”