Fossil hunters trace the rise of dinosaurs to the frigid winters the beasts endured on their forays through the far north.
Animal footprints and rock sediments from northwestern China indicate that dinosaurs adapted to the cold of the polar regions before a mass extinction event paved the way for their domination at the end of the Triassic.
With a blanket of misty feathers to help them stay warm, the dinosaurs were better able to acclimatize and take advantage of new territories as brutal conditions wiped out vast swathes of the most endangered creatures.
“The key to their eventual dominance was very simple,” said Paul Olsen, lead author of the study at Columbia University’s Lamont-Doherty Earth Observatory. They were basically cold-adapted animals. When it was cold everywhere, they were done and the other animals weren’t.”
The first dinosaurs are believed to have appeared in the temperate south more than 230 million years ago, when most of the earth formed a vast subcontinent called Pangea. Dinosaurs were originally a minority 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, regarding 202 million years ago, more than three-quarters of terrestrial and marine species were wiped out in a mysterious mass extinction linked to massive volcanic eruptions that drove much of the world into cold and darkness. The devastation paved the way for the era of dinosaurs.
Write Scientific progress, an international team of researchers explains how the mass extinction helped dinosaurs rise to supremacy. They began studying dinosaur footprints from the Jonggar Basin in Xinjiang, China. These studies showed that dinosaurs lurked along beaches at high latitudes. In the late Triassic, the basin was within the Arctic Circle at regarding 71 degrees N.
But the scientists also found small pebbles in the fine sediments of a basin that once hosted several shallow lakes. The pebbles have been identified as “ice-packed debris,” meaning they were carried away from the lake shores on sheets of ice before falling to the bottom as the ice melted.
Taken together, the evidence suggests that dinosaurs not only lived in the Arctic, but thrived despite frigid conditions. After adapting to the cold, dinosaurs prepared to conquer new territories where the dominant, cold-blooded species died out in mass extinctions.
Dinosaurs are often categorized as tropical jungle animals, said Stephen Brusatte, a professor of paleontology at the University of Edinburgh, who was not involved with the research. He said the new research showed they would have been exposed to snow and ice at higher latitudes.
“Dinosaurs would have lived in these cold and icy regions and had to deal with snow, frostbite and all the things that humans living in similar environments have to deal with today. How did dinosaurs do it? Her secret was her feathers.”
“The feathers of those first primitive dinosaurs would have provided a soft coat to keep them warm in the intense cold. These feathers then seem to have come in handy when the world suddenly and unexpectedly changed and huge volcanoes began to erupt at the end of the Triassic, causing most of the world to be plunged into cold and darkness during frequent volcanic winter events.