Jun. 27—Newfound remains of baby dinosaurs tell a fascinating story about the lives of the creatures that used to inhabit the Arctic tens of millions of years ago.
The discoveries, involving mostly baby dinosaur bones and teeth, suggest that dinosaurs may have survived far north in Alaska for the entire year and laid eggs there, even though previous theories held that they likely migrated south to warmer areas during the harsh winter.
"Not only were they capable of living there during the summer, somehow, but they're actually reproducing up there — and not just one or two species but several different species, meat and plant eaters alike," said University of Alaska Museum of the North director Pat Druckenmiller, who worked on the findings.
A baby dinosaur didn't hatch until as many as five months after the egg was laid, he said. That means baby dinosaurs were just hatching by early fall — giving them a tiny window to begin migrating before winter set in.
By that time, Druckenmiller said, it's hard to imagine such a small, little dinosaur traveling on such a long journey south.
"They just didn't have time to migrate, so they had to be there year round," said Greg Erickson, a Florida State University professor who worked on the research. "There was no choice, it's just not possible."
Researchers found hundreds of specimens from baby dinosaurs at sites along the Colville River in northern Alaska, including some that were hatchlings as well as embryos.
The research is a culmination of over a decade's worth of work. And it's tedious. Researchers drove from Fairbanks up to Prudhoe Bay before they hopped into a plane or helicopter to land on a gravel bar in the Colville River, then traveled by boat to their research sites.
From there, they found what Druckenmiller called "little gold mines," or small deposits with a particular look that have a high number of bones, teeth and other fossils. Researchers then excavated the bones and saved the sediment before washing and screening it.
"We save every particle of sediment larger than half a millimeter," Druckenmiller said. "That's tiny stuff."
Back at the lab, researchers then looked through a microscope for more small teeth — some of which could fit easily on the head of a pin, he said.
Such small teeth are really hard to find, which makes the work impressive, said Michael D'Emic, an associate professor of biology at Adelphi University who studies the dinosaur teeth and bones but did not work on the study.
Winter in the Arctic when the dinosaurs were alive was a bit warmer than it is now, somewhat like Juneau's current climate, Druckenmiller said. There were freezing temperatures and presumably snow, he said.
Plus, winter meant three or four months of total darkness with little in the way of vegetation to eat.
That's why this research asks more questions than it answers, Erickson said.
How exactly did the dinosaurs survive the cold and the dark months?
That's yet to be known, Erickson said, though he speculated some smaller dinosaurs may have burrowed underground to hibernate.
But that leaves the question of how the bigger dinosaurs stayed alive through winter.
He guessed that perhaps the larger dinosaurs fasted in winter or may have done what musk ox or moose do in the winter these days, scrounging for things like bark, rotting wood, ferns or moss.
He also said he suspected some dinosaurs up north may have had thick feathers to keep warm, though it's really all speculation at this point.
The new research, detailed in the journal Current Biology, also adds evidence to the idea that the dinosaurs may have been warm-blooded in order to live in such cold environments, Erickson said.
"We know they could live in desert environments. We know they could live in very tropical environments," Erickson said. "Now, we know that they can also tolerate pretty darn cold environments, too."