The High Arctic experiences months of darkness in winter, which can pose a challenge for human inhabitants, just as it did for dinosaurs who occupied the region some 70 million years ago. Paleontologists have long wondered whether dinosaur species found along Alaska's North Slope migrated south in winter to evade the perpetual darkness and freezing temperatures. Now, the rare discoveries of hundreds of fossils from baby dinosaurs of many species, who were incapable of traveling long distances, offers "the strongest evidence yet that Alaska’s dinosaurs stayed year-round," per Smithsonian. Baby dinosaur fossils are notoriously hard to find because they're so tiny—some as small as "pinheads or dandruff flakes," one expert tells the Guardian—and because young dinos were easy prey. But on cliffs along the Colville River, paleontologists hit the motherload.
Over three decades, the Prince Creek Formation, the largest Cretaceous formation of baby dinosaur fossils in North America, has given up more than 100 bones and teeth from baby dinosaurs of seven species, per Live Science. "Not just one of the dinosaurs was nesting up there, but it looks like almost all of them, if not all of them," Florida State University palaeobiologist Gregory Erickson, co-author of the study published Thursday in Current Biology, tells the Guardian. These Arctic dinosaurs were likely warmblooded. Some studies suggest they grew quickly during the warm season and stopped growing in the cold season, "creating rings in their bones, similar to tree rings," per Smithsonian. But lead author Patrick Druckenmiller of the University of Alaska wants to dig deeper. "What food helped the herbivores survive in the winter?" he asks. "Did the small species burrow and hibernate?" (Read more dinosaurs stories.)