Fossil hunters trace the rise of dinosaurs to the freezing winters the beasts endured as they roamed the far north.
Animal footprints and rock sediments from northwest China suggest that dinosaurs adapted to the cold of the polar regions before mass extinction events paved the way for their reign at the end of the Triassic period.
With blankets of misty fur to help keep them warm, dinosaurs were better able to adjust and take advantage of new territory when brutal conditions swept across some of the most vulnerable creatures.
“Their key dominance is very simple,” said Paul Olsen, lead author of the study at Columbia University’s Lamont-Doherty Earth Observatory. They are basically cold-adapted animals. When things are cold, they are ready, and the other animals are not.”
It is believed that the first dinosaurs appeared in the southern temperate regions more than 230 million years ago, when most of Earth’s land mass formed a giant subcontinent called Pangea. Dinosaurs were originally a minority group that lived mainly in the highlands. Other species, including the ancestors of modern crocodiles, dominate the tropics and subtropics.
But at the end of the Triassic period, some 202 million years ago, more than three-quarters of both terrestrial and marine species were wiped out in a mysterious mass extinction event linked to a massive volcanic eruption that propelled much of the world into cold and darkness. Destruction paved the way for the era of dinosaurs.
Writing scientific progress, an international research team explains how mass extinctions helped dinosaurs dominate. They started by researching dinosaur footprints in the Junggar Basin in Xinjiang, China. This study shows that dinosaurs lurked along the coast at high latitudes. In the late Triassic period, the basin was located within the Arctic Circle, about 71 degrees N.
But scientists have also found tiny pebbles in the fine sediments of the basin that once housed several shallow lakes. The pebbles have been identified as “ice debris,” meaning they are carried from the lake’s shores on top of the ice sheet before falling to the bottom as the ice melts.
Together, the evidence suggests that dinosaurs not only lived in the Arctic, but thrived despite freezing conditions. After adapting to the cold, the dinosaurs prepared to take over new territory where the dominant cold-blooded species died out in a mass extinction.
Dinosaurs are often categorized as tropical forest animals, said Stephen Brusatte, a professor of paleontology at the University of Edinburgh who was not involved in the study. He said new research suggests they will be exposed to snow and ice at higher latitudes.
“Dinosaurs would have lived in these cold and icy areas and had to deal with snow, frostbite and all the other things that humans living in the same environment would have to deal with today. So how did the dinosaurs do it? Their secret is their fur.”
“The feathers of these first primitive dinosaurs would have provided a soft layer to keep them warm in the high cold. These feathers then seem to come in handy when the world suddenly and unexpectedly changes, and giant volcanoes begin to erupt late in the year. the Triassic period, resulting in the Plunging of much of the world into cold and darkness during frequent volcanic winter events.”
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