A new species of duck-billed dinosaur was discovered in a remote part of northern Alaska. Called Ugrunaaluk kuukpikensis, it’s the northernmost dinosaur discovered thus far, and researchers think it was a cold-adapted plant-eater that thrived in the wintry darkness of the polar region. It may have even seen snow. 

"The finding of dinosaurs this far north challenges everything we thought about a dinosaur's physiology," Florida State University’s Greg Erickson said in a statement. "It creates this natural question. How did they survive up here?"

More than 9,000 bones from various animals were unearthed along the Colville River in the Prince Creek Formation, 6,000 of which were from hadrosaurs (duck-billed dinosaurs). Most of the fossils were collected from a single rock layer called the Liscomb Bonebed, which was deposited on a coastal flood plain about 69.2 million years ago. During the Late Cretaceous, the site was located well above the paleo-Arctic Circle, and that means the dinosaurs were living as far north as land was known to have existed. Arctic Alaska at the time was covered with trees, and the average temperature was about 5-6 degrees Celsius (42-43 degrees Fahrenheit), which is milder than nowadays. But because they were so far north, the dinosaurs likely spent the winter months – when it dropped down to 2 degrees Celsius (36 degrees Fahrenheit) – living in darkness. 

Ugrunaaluk had scales, plates on its back, a broad bill for grazing low-lying plants, teeth for grinding, and it may have walked on two feet. Researchers initially thought the skeletal remains belonged to Edmontosaurus, another duck-billed dinosaur that lived roughly 70 million years ago in Montana, South Dakota, and Alberta, Canada. However, by analyzing the bone structure, Hirotsugu Mori from the University of Alaska Fairbanks (UAF) and colleagues revealed that certain features of the skull – especially around the mouth – weren’t present in any known duck-billed species. 

After working with Alaskan Iñupiaq language speakers, the team arrived at the name Ugrunaaluk kuukpikensis, which means “ancient grazer” of the Colville River. The work was published in Acta Palaeontologica Polonica this week. 

One of the things that made identifying this new species difficult at first – besides the frigid, remote location that required bush planes, inflatable boats, and rappelling down a cliff face – is how most of the fossils came from younger or juvenile dinosaurs. Likely a herd of juveniles was killed suddenly. "A challenge of this study was figuring out if the differences with other hadrosaurs was just because they were young, or if they were really a different species," said UAF’s Patrick Druckenmiller. "Fortunately, we also had bones from older animals that helped us realize Ugrunaaluk was a totally new animal." The adults were about 9 meters (30 feet) long.

The researchers estimate that the fossil-rich area contains at least 13 different dinosaur species. "Alaska is basically the last frontier," Erickson adds. "It's virtually unexplored in terms of vertebrate paleontology. So, we think we're going to find a lot of new species."