Hot dinosaurs have captured the public’s imagination. Our favorite prehistoric giants are often depicted roaming dry savannas or munching on tropical leaves.
But some dinosaurs had a cold lifestyle. Baby dinosaur bones and teeth deposit in northern Alaska, Reported on Thursday in Current Biology, suggest Many species survived year-round above the Arctic Circle – freezing temperatures, food shortages and four straight months of darkness, as well as the occasional snow storm.
footprints of the first polar dinosaur were found in 1960Entered the Svalbard archipelago. In the following decades, evidence of dinosaurs in both Arctic and Antarctic Latitudes arose. This aroused curiosity about how they managed – particularly in northern regions, which are warmer than they are today, yet perpetually turn into a nocturnal frozen landscape during the winter.
“How did they do this?” said Patrick Druckenmiller, a paleontologist at the University of Alaska Museum of the North who worked on the new study. He said the dinosaurs were probably snowbirds, spending the summers before migrating south. “Or did they somehow make it harder? Or do something crazy, like hibernation?”
For this study, researchers headed to the Prince Creek Formation in northern Alaska above the Arctic Circle and “the most polar dinosaurs we know,” Dr. Druckenmiller said.
While the popular image of fossil-hunting also comes from warmer climates – sun-baked paleontologists scrambling for clues, female hambones peeking out of the ground – Prince Creek is less glamorous. “The ground is frozen, the bones are frozen,” said Tyler Hunt, a Ph.D. he said. Florida State University students working on the project. “Everything is muddy.”
During several visits, Mr. Hunt, Dr. Druckenmiller and other researchers removed icy sand and mud from the Prince Creek hills and allowed it to melt in the sun. Then he always sifted the dirt through a fine mesh screen, keeping nothing bigger than a poppy seed. The haul was taken back to the lab, where several students and volunteers combed through a spoon at a time under microscopes, examining small pieces of bones and teeth, called microfossils.
Often overlooked in favor of “large, shiny” remains, microfossils “provide a window into the life of baby dinosaurs,” said Holly Woodward Ballard, a paleontologist at Oklahoma State University, as well as animals and plants. can coexist. who was not involved in the study.
The team found microfossils from at least seven different late Cretaceous dinosaur species, including tyrannosaurs, ridge-headed ceratopsians and duck-billed hadrosaurs.
Dr. Druckenmiller said finding evidence of young dinosaurs – including some that have not yet hatched – helps our understanding of polar dinosaur lifestyles. recent estimates of Dinosaur egg incubation time – in some cases it can take up to six months – the timeline for winter migration becomes much stricter, he said, adding that they “have to hatch out of eggs and start running south.”
Instead, dinosaurs may have found ways to keep themselves and their offspring warm and fed. It’s possible that some of them have their wings facing down, Dr. Druckenmiller said. The finding also supports the increasingly popular idea that dinosaurs were not “cold, lizard-like creatures” but endotherms, capable of generating their own body heat, he said.
Other behaviors, such as hibernation, are “entirely possible,” Dr. Ballard said, but not yet borne out by the evidence at any of the fossil sites.
“It’s exciting to see that the whole story comes together so beautifully,” said David Fastowski, a paleontologist at the University of Rhode Island who was not involved.
The team plans to return to Prince Creek to uncover more details, looking for signs of fossilized feathers and comfortable dinosaur bills. When Mr. Hunt moves from sunny Florida to a cold Arctic excavation site, he thinks of the unlikely pioneers who came before him.
“You don’t see a picture of dinosaurs in the snow, you know?” he said. “But clearly they can grow there.”