A team of paleontologists has been scraping away at the mud on a riverbed in far northern Alaska. They discovered evidence of dinosaurs mating towards the top of what is now North America, indicating that dinosaurs lived full-time in cold temperatures throughout the late Cretaceous period.
The revelation has ramifications for our knowledge of dinosaur bloodlines, morphology, and behavior. The discoveries were found in the Prince Creek formation, located in a section of Alaska so far north that it takes four days to get there by car, aircraft, and boat from Fairbanks. For the past 70 years, scientists have traveled to remote areas of federal property to learn how dinosaurs survived.
Climate Throughout the Ages
Although the climate was warmer 70 million years ago, dinosaurs living in the far north would have had to contend with temperatures barely above freezing during the winter months, which would have been gloomy and desolate. There would be evidence of the creatures remaining in the Arctic throughout the Cretaceous winters if they weren't moving south.
In a video chat, Patrick Druckenmiller, a paleontologist at the University of Alaska Museum and the paper's primary author, stated, "Dinosaurs nested in the Arctic-not just barely in the Arctic, but far up in the Arctic, virtually in the North Pole." "This clearly implies they were overwintering rather than migrating. And if they did overwinter, it raises a slew of new concerns about how they accomplished it."
Ancient Animal's Temperature Control
Reptiles are cold-blooded or ectotherms, implying that the animal's internal temperature is determined by the outside temperature. That's why lizards like to dwell in sunny areas of the world, whether dry or humid, but not in locations where it becomes too cold. On the other hand, endotherms that have body heat and control their own temperature may survive in such cold situations if they have a consistent food source, access to water, and protection from the elements.
If you're a large dinosaur without children, migration is a lot simpler. However, these researchers discovered dinosaurs of various ages and sizes, including duck-billed hadrosaurs and meat-eating tyrannosaurs, as well as tiny mammals and other animals. Tom Rich, an Australian vertebrate paleontologist who was not involved in the new article, has earlier reported the first evidence of a non-avian dinosaur in a polar habitat. According to Rich, because of the energy required, migration south for the winter didn't seem conceivable for creatures that couldn't fly.
Testing Soil Samples
Druckenmiller's team carried sheaths of soil from the banks of the Colville River into their lab, where it was sieved for microfossils using fine-toothed screens. Any granules of material bigger than half a centimeter in diameter were screened out of the soil. "Now we have dirt that is clean," Druckenmiller remarked. "Then we place a little spoonful of this dried sand on a dish and examine every single grain with a microscope."
The crew was hunting for tiny things, and they eventually discovered it in the form of several perinatal dinosaur bones and teeth, which were proof of the newborn creatures up north. The bones were all the same mottled fossil hue and fractured, so they couldn't be used to identify any specific species. The form of the teeth, however, allowed the researchers to trace them to their ancient owners. They haven't found any dinosaur eggs, but baby dinosaurs are definitely further evidence of dinosaurs settling in that far north.
Cretaceous Birds and Mammals
Surprisingly, apart from dinosaurs, the only creatures discovered so far in Prince Creek are warm-blooded Cretaceous birds and mammals. To put it another way, animals that we recognize as warm-blooded. Amphibians and crocodilians, which have cold blood, have yet to be discovered at such latitudes. In a statement, co-author Gregory Erickson, a paleontologist at Florida State University, stated, "I think this is some of the most convincing evidence that dinosaurs were in fact warm-blooded."
What about the dinosaurs' ability to survive the winter? Imagine a tyrannosaur in the winter, and they may have been feathered to protect them from the cold. "Ectotherms don't have exterior coverings like that," Druckenmiller explained, "but it makes perfect sense for an animal living up in the Arctic to desire a down parka." Furthermore, he speculated that the dinosaurs may have hibernated during the cold winter months. However, no evidence of dinosaur burrows has been discovered. But that may happen when the crew sifts through layers of the 70-million-year-old stream bed seeking clues.
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