Science has known since the 1950s that dinosaurs also lived in the Arctic. But it was long thought that the animals would move south in the winter and return in the summer – as are many migratory birds today. But the discovery of fossil juveniles now suggests that at least some species spent entire years in polar latitudes giving birth and raising their offspring there. A group around Patrick Druckermiller of the University of Alaska Museum of the North reports in “Current Biology.”.
Druckermiller and Company excavated hundreds of tiny teeth and bones that were only a few millimeters in size in the Prince Creek Formation in northern Alaska. The team was able to assign a total of seven species of dinosaurs that died in eggs or after hatching. This region was beyond the Arctic Circle 70 million years ago. To reach the regions south of it, dinosaurs would have to cover a distance of at least 3,000 kilometers: on foot, as scientists insist.
They therefore assume that the species involved remain at the site throughout the year and thus even during the long polar night. The incubation period of dinosaurs was estimated to be five or six months. If they had laid eggs in spring, the young would not lay eggs until autumn: given the long migration, it is too late. It is unlikely that they will be able to avoid it. Instead, the animals could have already been brooded in winter, so that the offspring could gather enough strength for the long, cold season in the summer.
Evidence of dinosaurs in this fossil site is by far the farthest north. Petrified trees from the time suggest that conditions were not as snowy as they are today. Still, the animals had to survive the long, cold polar night. At the time of the dinosaurs, this area was ten degrees further north than it is today.
