Fossil hunters have traced the rise of dinosaurs to the icy winters that the beasts suffered as they wandered the far north.
Animal footprints and stone deposits from northwestern China suggest that dinosaurs adapted to the cold in the polar regions before a mass extinction event paved the way for their reign in the late Triassic.
With a cover of fuzzy feathers to help keep them warm, dinosaurs were better able to cope and take advantage of new territories when brutal conditions wiped out large strips of more vulnerable creatures.
“The key to his eventual mastery was very simple,” said Paul Olsen, lead author of the study at Columbia University’s Lamont-Doherty Earth Observatory. “They were animals basically adapted to the cold. When it was cold everywhere, they were prepared, and other animals were not.”
The first dinosaurs are believed to have arisen in the temperate south more than 230 m ago, when most of Earth’s earth formed a supercontinent called Pangea. Dinosaurs were initially a minority group, living mainly at high altitudes. Other species, including the ancestors of modern crocodiles, dominated the tropics and subtropics.
But by the end of the Triassic, about 202 million years ago, more than three-quarters of terrestrial and marine species were wiped out in a mysterious mass extinction event linked to vast volcanic eruptions that sent much of the world into the cold. and darkness. The devastation set the stage for the reign of the dinosaurs.
Writing in Science Advances, an international team of researchers explains how mass extinction could have helped dinosaurs gain dominance. They began by examining the dinosaur footprints of the Junggar Basin in Xinjiang, China. These showed that dinosaurs hid along the coasts at high latitudes. By the end of the Triassic, the basin was within the Arctic Circle, about 71 degrees north.
But scientists also found small pebbles in the sediments usually up to the basin, which once contained several shallow lakes. Pebbles were identified as “ice results,” meaning they were carried from the shores of the lake onto sheets of ice before falling to the bottom when the ice melted.
Taken together, the evidence suggests that dinosaurs not only lived in the polar region, but thrived despite freezing conditions. Having adapted to the cold, the dinosaurs were willing to take over new territories as the dominant, cold-blooded species died in mass extinction.
Stephen Brusatte, a professor of paleontology at the University of Edinburgh who was not involved in the research, said dinosaurs were often typified as beasts living in rainforests. New research showed they would have been exposed to snow and ice at high latitudes, he said.
“Dinosaurs would have lived in these cold, icy areas and would have had to deal with snow and frost and all the things that humans living in similar environments have to deal with today. So how were they able to cope?” what about the dinosaurs? Their secret was their feathers, “he said.
“The feathers of these early primitive dinosaurs would have provided a furry coat to keep them warm in the high-latitude cold. And it seems that these feathers were useful when the world changed suddenly and unexpectedly, and giant volcanoes began. to erupt in the late Triassic, submerging much of the world in cold and darkness during repeated winter volcanic events. “