Non-avian dinosaurs nested in the Arctic, paleontologists say

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Non-avian dinosaurs nested in the Arctic, paleontologists say. A team of paleontologists from the University of Alaska Fairbanks and Florida State University has discovered the first concrete evidence that many types of dinosaurs, from small bird-like dinosaurs to giant tyrannosaurs, not only lived in Alaska during the Late Cretaceous era. , but the nest was also built there.

Non-avian dinosaurs

A pair of adult Nanukasaurus tyrannosaurs and their young. It wasn’t long before people were surprised to learn that dinosaurs lived in the Arctic 70 million years ago, said the director and researcher of the Department of Geology at the Museum of the North at the University of Alaska, Dr. Pat said. Druckenmiller. at the University of Alaska Fairbanks.

We now have clear evidence that they were nesting there too. This is the first time anyone has shown that dinosaurs can reproduce at these high latitudes. Previous studies at a handful of other sites provided evidence that one or two indeterminate dinosaur species were capable of nesting near or just above the Arctic or Antarctic Circle.

Ancient arctic ecosystem

Environmental conditions at this time and place indicate challenging seasonal extremes, with mean annual temperatures of approximately 6 ° C (approximately 40 ° F). There must have been almost four months of complete winter darkness along with the cold conditions. “Finding out that not all of these species have even reproduced in the Arctic is really remarkable,” said Druckenmiller.

Dr. Druckenmiller and his colleagues documented the ancient arctic ecosystem of the Prince Creek Formation in northern Alaska, including its dinosaurs, mammals, and other vertebrates. They found hundreds of tiny dinosaur bones, including tiny teeth from individuals that were still in the egg or that had just erupted.

Arctic dinosaur

Arctic dinosaur types include small- and large-bodied herbivores, including hadrosaurs (duck-billed dinosaurs), ceratopsians (horned dinosaurs and leptoceratopsians), thesaurus, and carnivores (tyrannosaurs, troodontids, and dromaeosaurs).

Comparative size of immature and mature dinosaur teeth from the Prince Creek Formation, Alaska. One of the biggest mysteries about Arctic dinosaurs was whether they migrated north seasonally or were year-round residents, said Professor Gregory Erickson, a researcher in the Department of Biological Sciences at Florida State University.

Unexpectedly, we found the perinate remains that represent almost all types of dinosaurs in Genesis. It was like a prehistoric maternity ward. Once they learned that dinosaurs were nesting in the Arctic, scientists realized that the animals spent their entire lives in the region.

Their previous research has shown that the incubation period for this type of dinosaur ranges from three to six months. Royal Tyrrell paleontologist Dr Caleb Brown said winters would have been deep and hazy, with 24 hours of sunlight in the summer – very good conditions for a growing dinosaur if it grew fast enough before the onset of winter. Can museum.

“The Arctic habitat throughout the year provides a natural test of animal physiology,” said Professor Eriksson. We solved many long-standing mysteries about the reign of the dinosaurs, but we opened a new can of insects. How did they survive the arctic winter?

“Maybe the little ones hibernated for the winter. Maybe others lived on poor quality forages, like today’s elk, until spring,” said Dr. Druckenmiller. Paleontologists have found fossils of warm-blooded animals in the region, but not snakes, frogs, or turtles, which were common at lower latitudes. This suggests that the cold-blooded animals were not prepared to survive in the low temperatures of the region.

“This study gets to the heart of one of the oldest questions among paleontologists: Were dinosaurs warm-blooded? We think endothermy was probably an important part of their existence,” Druckenmiller said. The team’s article was published in the journal Current Biology.

Decline in the biodiversity of dinosaurs before the Chicxulub asteroid impact: study. The most famous mass extinction was the disappearance of non-avian dinosaurs at the end of the Cretaceous period, 66 million years ago, after ruling the Earth for 170 million years. The best supported extinction model is the impact of a large asteroid at Chicxulub, Mexico.

Chicxulub Asteroid

However, it is widely debated whether dinosaurs were in decline prior to the Chicxulub impact. A study in the journal Nature Communications provides new evidence for an environmentally driven global decline in groups of dinosaurs prior to the asteroid impact. Condamine et al.

Analyze the species extinction dynamics for six major families of dinosaurs and trace the decline of dinosaurs, where diversification changed to a pattern of diversity of decline 76 million years ago. Image credit: Jorge González.

Dinosaurs

Condamine et al. Analyze the species extinction dynamics for six major dinosaur families and find dinosaur declines, where diversification changed to a decline diversity pattern 76 million years ago. “We looked at the six most abundant dinosaur families (Ankylosauridae, Ceratopsidae, Hadrosauridae, Dromaeosauridae, Troodontidae, and Tyrannosauridae) throughout the entire Cretaceous period, spanning 150 to 66 million years ago, and found that they were all evolving, expanding, and clearly succeeding. ” said Dr. Fabian Condamine.

Researcher at the Institut des Sciences de l’Evolution de Montpellier and the CNRS. Then 76 million years ago, they show a sudden recession. Their extinction rate increased and in some cases the rate of origin of new species decreased.

Dr. Condamine and his colleagues used Bayesian modeling techniques to account for a variety of uncertainties such as the incomplete fossil record, uncertainty about the dating of fossils, and uncertainties about evolutionary models.

Each of the models was run millions of times to consider all of these possible sources of error and to determine whether the analyzes would converge on an agreed most probable outcome. “In all cases, we found evidence of degradation before the bolide effect,” said Dr. Guillaume Guinot, a researcher at the Institut des Sciences de l’Evolution in Montpellier and CNRS.

“We also looked at how these dinosaur ecosystems functioned, and it was clear that the herbivorous species first disappeared, and this made the last dinosaur ecosystems unstable and prone to collapse if environmental conditions were harmful.”

“We used more than 1,600 carefully examined records of dinosaurs during the Cretaceous,” said Professor Phil Curry, a paleontologist at the University of Edmonton. I have been collecting dinosaurs in North America, Mongolia, China, and other regions for some time, and have seen a great improvement in our knowledge of the age of dinosaur rock formations.

This means that the data improves all the time. The decline of the dinosaurs in their last ten million years is understandable and, in fact, is the best part of their fossil record as our study shows. In the analysis, we explored a variety of possible causes of the decline of the dinosaurs, said Professor Mike Benton, a paleontologist at the University of Bristol.

It became clear that there were two main factors, the first was that the climate in general was getting colder, and this made life difficult for the dinosaurs, who probably depended on warmer temperatures. Later, the loss of herbivores destabilized the ecosystem and threatened extinction.

 

biodiversity of dinosaurs
biodiversity of dinosaurs

 

We also found that dinosaur species that lived the longest were more prone to extinction, perhaps indicating that they were unable to adapt to new conditions on Earth. It was a turning point in the evolution of life, said Dr. Kondamine. The world was dominated by dinosaurs for more than 160 million years, and as they surpassed other groups, including mammals, their dominance began to increase.

The dinosaurs were mostly so large that they hardly knew that the small furry mammals were underground. But mammals began to increase in species numbers before the dinosaurs left, and then after the impact, it gave them the opportunity to create the new types of ecosystems we see today.

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