Dinosaur Find

What caused the death of dinosaurs? Scientists have blamed their demise on everything from lowered sea levels to lowered sperm counts. Now William Clemens, a paleontologist at the University of California, Berkeley, has added to the mystery. His expedition, sponsored by the U.S. Geological Survey, uncovered a cache of 180 dinosaur bones in Alaska, several hundred miles farther north than the creatures had previously been found. Among the fossils are skeletal remains of hadrosaurs, plant-eating duck-billed dinosaurs that stood up to 15 ft. high, and the teeth of a Tyrannosaurus-type carnivore.

In Clemens' view, the discovery indicates that at least some dinosaur species were not sensitive tropic dwellers but were able to survive through chilly and dark Arctic winters lasting from November to February. That theory tends to undermine the currently popular asteroid version of the apocalypse. According to that model, all dinosaurs perished when an asteroid or comet collided with the earth and tossed obscuring dust into the air, blocking sunlight and lowering ground temperatures. Clemens counters that dinosaurs living up north would hardly have noticed the difference, let alone be wiped out. Says he: "It doesn't matter if your long winter night is the result of an asteroid cloud or just a seasonal period of darkness."

Some scientists remain unconvinced, pointing out that the Alaskan climate may have been milder 65 million years ago. Alternatively, northern dinosaurs may have migrated to more temperate climes or lapsed into a kind of hibernation every winter. Says David Stone, a geophysicist at the University of Alaska: "This is a very limited number of dinosaurs we're talking about. It doesn't have much to say about the adaptability of dinosaurs around the world to sudden darkness."