How did duck-billed dinosaurs survive in Alaska?

In a study published Tuesday, researchers have found evidence for a species of polar dinosaur unique to Northern Alaska.

Researchers announced Tuesday the discovery of a new species of plant-eating dinosaur in Northern Alaska. 

The existence of hadrosaurs, also called duckbills, in Alaska's Prince Creek Formation area has been known since the first fossils were found in 1961, but scientists have only recently classified them as having belonged to a distinct species. Authors of the paper published in the Acta Palaeontologica Polonica suggest that the species grew up to 30 feet long and had hundreds of teeth to chew the coarse vegetation native to the area 70 million years ago. Researchers also believe the species was able to walk on either two or all four legs.

The species was identified as a hadrosaur and named Ugrunaaluk kuukpikensis, which means ‘ancient grazer’ in the language used by native Alaskan Inupiat Eskimos.

Hirotsugu Mori, a graduate student at the University of Alaska Fairbanks and a co-author of this paper, said in a press release,“The new species has a unique combination of characteristics not seen in other dinosaurs,” such as a distinct skull shape.

Recognizing these dinosaurs as their own species is crucial for paleontologists, because it suggests that Ugrunaaluk lived in the same place year-round, instead of migrating south in the winter, as was previously expected.

"The types of dinosaur we're finding are all unique to Alaska," said Patrick Druckenmiller, an Earth Sciences curator at the University of Alaska Museum of the North and author of the paper, in a interview with The Christian Science Monitor. Researchers have discovered 12 or 13 dinosaurs species distinct to northern Alaska, making it home to "unique inhabitants of a polar community."

“We are finding a lot of young and old [Urgrunaaluks], and we don’t have similar dinosaur evidence at lower latitudes, at this time in history,” Gregory Erickson, a professor and researcher at Florida State University, explained during an interview with the Monitor. And “unusual growth lines in their teeth” also serve as evidence that these were polar dinosaurs. “Because they are constantly replacing their teeth, and because they are always showing the same evidence, it proves they didn’t move south.”

But if they didn’t migrate, how did they survive?

“This area was warm relative to what it is today,” explains Dr. Erickson. His research suggests that the area was around 40 degrees Fahrenheit on average, and he compares the climate to that of British Columbia. 

Erickson suggests that this evidence is extraordinary, even if it was more temperate than what we see today. At 80 degrees north, these dinosaurs experienced snow and lived in complete darkness for three to five months of the year. And for these vegetarians, these dark months meant hard times for food.

"They were probably living off of poor-quality foliage off the forest floor," during the dark months, says Dr. Druckenmiller. Such as "twigs and bark from weird conifers living during that time."

“They were living under conditions we don’t normally associate with dinosaurs,” Erickson adds. “This adds to the mystery.”

Specifically, the mystery surrounding whether dinosaurs were cool-blooded or warm-blooded.

Only endothermic species, that is, animals that can make their own heat, have been discovered in this area. Because Urgunaaluk could tolerate the cold weather, the findings “favor the warm-blooded hypothesis,” says Erickson. It is also noteworthy that we have never found evidence of cold blooded reptiles, such as crocodiles or lizards, living in this area, he says. Urgunaaluks are acting as “a natural test of dinosaur physiology.”

Researchers are excited for future discoveries in Alaska.

“We think we’ve found a lost world of dinosaurs,” says Erickson. “Alaska is unexplored paleontologically. Down the road, I think you are going to see some intriguing discoveries about the biology of dinosaurs.”