Polar Dinosaurs Tougher than Nuclear Winter?
A colossal meteorite that slammed into Earth about 65 million years ago may have killed the dinosaurs, but there's a good chance it did not. The proof may be locked in the permafrost of Alaska's north slope.
A 60-mile stretch of the Colville River holds layers of well-preserved dinosaur bones that researchers can't reach using conventional methods. Roland Gangloff and his colleagues hope to get funding soon to mine the permafrost for fossils and possibly unearth one of the greatest riddles of history—what killed the dinosaurs?
Gangloff is earth science curator of the University of Alaska Museum in Fairbanks and an associate professor of geology and geophysics. He teamed with Australian colleagues Thomas Rich and Patricia Vickers-Rich to write a paper on polar dinosaurs published in the February 8, 2002 issue of the journal Science.
The far-north and far-south dinosaur hunters suggest that polar dinosaurs were some of the most adaptable creatures to ever live, perhaps too resilient to be killed by the affects of one giant asteroid. The prevailing theory on the demise of the dinosaurs is that a meteorite struck Earth about 65 million years ago, kicking up dust that blocked the sun's rays and chilled the planet to temperatures intolerable for dinosaurs.
"If dinosaurs adapted to such a variety of environments, how did one nuclear winter knock them off?" Gangloff said. "Anyone who explains the whole picture of dinosaur extinction has to explain high-latitude dinosaurs."
Arctic dinosaurs first made the news in the early 1960s, when geologists and paleontologists poking around the north found dinosaur footprints embedded in rock on the island of Spitzbergen and found dinosaur bones falling from the banks of the Colville River in Alaska. Since then, researchers have found scattered evidence of the creatures from the high Arctic of Canada to near the South Pole.
The Colville River remains the richest deposit in Alaska. Gangloff and many of his colleagues have found thousands of dinosaur bones from cutbanks along the river and bird-like tracks as large as a human hand embedded in nearby rocks. Paleontologists have found dinosaurs in a few other Alaska locations. "Lizzie," a hadrosaurus named after Lizzie May, was co-discovered by her stepfather Kevin May in the Talkeetna Mountains. Gangloff and other National Park Service-sponsored researchers found the first dinosaur footprint in Aniakchak National Monument and Preserve recently.
Alaska was a different place when dinosaurs roamed here. According to plant fossils dating to the period from 85 to 100 million years ago—a time consistent with the fossilized dinosaur tracks—Alaska had a climate similar to the southern California coast. Alaska's climate was more like the coasts of Oregon and Washington 68 to 85 million years ago, the period to which paleontologists have dated most of the bones found near the Colville River.
The Australian researchers found dinosaur bones alongside prehistoric evidence of permafrost in southeastern Australia. Using oxygen-isotope methods to determine the average temperatures at the time the far-south dinosaurs lived, the scientists came up with a reading of about -2 degrees Celsius. The modern mean annual temperature of Fairbanks is -2.9 degrees Celsius.
Alaska and Australia paleontologists have both discovered species of dinosaur with bulging eyes and brains, which may have been an adaptation to low light. Far-north hadrosaurs left behind skulls with hundreds of teeth, possibly to grind up silica-rich ferns and horsetails that thrived in colder climates.
Dinosaurs that lived far from the warmth of the equator—possibly in climates as extreme as present-day Fairbanks—may make people rethink how dinosaurs lived and died. Hundreds of clues wait beneath the floodplain of the Colville River, frozen where dinosaurs died en masse millions of years ago.
