Madrid, 24 (European Press)
Almost all Arctic dinosaurs, from small, bird-like animals to giant dinosaurs, bred in the area and likely stayed there all year long.
That’s the conclusion that scientists from the University of Alaska Fairbanks and Florida State University report in a new article in the journal “Current Biology.”
“People were surprised not so long ago when they discovered that dinosaurs lived in the Arctic 70 million years ago,” recalls Pat Druckenmiller, lead author of the paper and director of the University of Alaska Museum of the North. It is the first time it has been shown that dinosaurs could reproduce at such high latitudes.”
The results contradict previous hypotheses that the animals migrated to lower latitudes for the winter and laid eggs in those warmer regions. It is also convincing evidence that they were warm-blooded.
For more than a decade, Druckenmiller and Gregory Erickson, professor of biological sciences at Florida State University, have been doing fieldwork at Prince Creek Formation in northern Alaska. They have discovered many types of dinosaurs, most of them new to science, on the cliffs above the Colville River.
His most recent finds are teeth and tiny bones from seven species of perinatal dinosaur, a term describing baby dinosaurs that are about to be born or are just being born.
said Erickson, one of the authors of the research paper. Training: “One of the biggest mysteries about Arctic dinosaurs was whether they migrated seasonally north or stayed year-round. It was like prehistoric maternity.”
Healing bones and teeth, some no bigger than a pinhead, requires persistence and a keen eye. On land, scientists drag buckets of sediment from the cliff face to the riverbank, where they launder the material through smaller and smaller sieves to remove larger rocks and dirt.
Once in their labs, Druckenmiller, Erickson and co-author Jaelyn Eberle of the University of Colorado at Boulder examined the material again. Then, with a teaspoon, the team, which included undergraduate and graduate students, examined the remaining loose particles under microscopes to find bones and teeth.
Druckenmiller says, “Recovering these microfossils is like searching for gold. It takes a great deal of time and effort to sort through tons of sediment grains by grain under a microscope. The fossils we find are rare, but scientifically rich in information.”
The scientists then worked with Caleb Brown and Don Brinkman of the Royal Tyrrell Museum of Paleontology in Alberta, Canada, to compare the fossils with those from other sites at low latitudes. These comparisons helped them conclude that the bones and teeth were from perinatal dinosaurs.
Once they learned that dinosaurs nested in the Arctic, they realized that the animals lived their entire lives in the area.
Erickson’s previous research revealed that the incubation period for these types of dinosaurs ranged from three to six months. Since summers in the Arctic are short, even if dinosaurs laid their eggs in the spring, their young would be too young to migrate in the fall.
Global temperatures were much warmer during the Cretaceous, but arctic winters would have included four months of darkness, freezing temperatures, snow, and little fresh vegetation to feed.
“As bleak the winter was, the summer had 24 hours of sunlight, ideal conditions for a growing dinosaur if it could grow fast enough before winter came,” says Brown, a paleontologist at the Royal Tyrrell Museum.
Erickson added that the year-round residence in the Arctic provides a natural test of the animals’ physiology.
“We’ve solved many ancient mysteries about the age of the dinosaurs, but we’ve opened a new can of worms, but how they survived the arctic winters,” he wonders. “The young may have gone into hibernation. Others may have lived on poor-quality forage, like today’s elk, until spring,” Druckenmiller says.
Scientists found fossils of warm-blooded animals in the area, but not snakes, frogs or turtles, which were common at low latitudes. This indicates that the cold-blooded animals were not prepared to survive the cold temperatures of the region.
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