Dinosaurs are usually associated with lush tropical forests and swamps. But a new species of hadrosaur, or duck-billed dinosaur, whose existence was just announced this week, came from a decidedly unsteamy locale: the North Slope of Alaska. Despite living in a milder age, this hardy hadrosaur suffered through months of darkness each winter and in all likelihood snow.
The first inkling of what researchers call a “lost world” of Arctic dinosaurs came in 1961, when a geologist for Shell Oil Company stumbled upon a cache of bones while mapping along the Colville River in northern Alaska. Assuming they belonged to large Ice Age mammals, he made no further effort to study them. But after dinosaur footprints were found elsewhere in the state, a second geologist took a look in 1984 and, with the help of some paleontologists, identified them for what they were: Alaska’s first dinosaur bones. (Around the same time, dinosaur remains were likewise discovered in Antarctica.)
Since then, scientists have excavated several thousand bones from the Alaskan site, over 6,000 of which belong to the same type of hadrosaur. “It’s the best-known polar dinosaur in the world,” says Patrick S. Druckenmiller, Earth sciences curator at the University of Alaska Museum of the North. “We have every single bone in the body multiple times over.” Scientists had previously lumped it in with the similar-looking Edmontosaurus, which lived further south. But in a paper published Tuesday in the journal Acta Palaeontologica Polonica, Druckenmiller and two colleagues declared it a separate species due to differences in skull anatomy. In collaboration with native Iñupiaq speakers, they named the new dinosaur Ugrunaaluk kuukpikensis (ancient grazer).
Although an adult Ugrunaaluk kuukpikensis could reach 30 feet in length, most of the bones found so far came from 9-foot-long juveniles. Druckenmiller speculates that a herd of them was wiped out in a sudden and catastrophic event some 69 million years ago. “It could be that these animals died crossing a stream,” he says, perhaps after rapid snowmelt from the nearby Brooks Range caused it to swell.
Owing to the vagaries of plate tectonics, Alaska was even further north then than it is now. Yet because the so-called age of dinosaurs was a much warmer era, the climate resembled modern-day British Columbia’s. Instead of treeless tundra, the North Slope was covered with deciduous conifers, as well as broadleaf shrubs, ferns and horsetails. The mean annual temperature was a comparatively balmy 41 to 43 degrees Fahrenheit. As Druckenmiller points out, though, “it still would have been a really tough existence.” Well equipped with hundreds of teeth, Ugrunaaluk kuukpikensis likely survived the winter by gobbling up twigs and bark, much like a reptilian moose, Druckenmiller explains. “Moose get pretty skinny up here by the time spring rolls around,” he says, “but most of them make it.”
Ugrunaaluk kuukpikensis is just one of 13 dinosaurs, including a relative of Tyrannosaurus rex, to be discovered in that part of Alaska, though it’s only the fourth that has been identified to the species level. None of these have turned up anywhere else, leading Druckenmiller to believe they were specially adapted to the Arctic’s harsh conditions. They may have even been warm-blooded, like today’s birds and mammals, or at least partially warm-blooded. “It looks like the northernmost dinosaurs that ever lived were these dinosaurs,” Druckenmiller says. “It’s a unique community. They’re not just northern populations of other species.” He points out that crocodile, turtle and lizard fossils have never been found on the North Slope, even though these cold-blooded reptiles were abundant elsewhere at that time.
Getting to the bonebed, located within the National Petroleum Reserve-Alaska about 100 miles south of the Arctic Ocean, is no easy task. Druckenmiller and his team must drive from Fairbanks to Prudhoe Bay, a two-day trip along a bumpy gravel road that parallels the Trans-Alaska Pipeline, and then charter a flight. “Believe me, we are about as remote as you can get,” Druckenmiller says. Yet he has already been seven times and has no plans to stop, expressing that new bones are constantly being exposed. “This is ground zero, really, for studying Arctic dinosaurs anywhere in the world,” he says.