Feathered theropod dinosaurs that eat mammals on snowy days. Image credit: Larry Felder
Having adapted to the polar climate, dinosaurs may have survived the extinction event at the end of the Triassic, when most other animals went extinct.
During the Late Triassic and Early Jurassic Periods, some dinosaurs may have evolved traits that could tolerate cold winters. This explains how they ruled the planet for the next 135 million years.
Analysis of rock sediments in the Junggar Basin, where dinosaur footprints have been found in northwestern China, shows that dinosaurs inhabited not only green tropical regions, but also in cold, frozen forests.
Paul Olsen and colleagues at Columbia University in New York found signs that the area often froze during the period of prehistoric reptile habitation. Sediments contain unusually large particles, which are typical of lakes that freeze every year.
Dinosaur fossils have been found near the poles, but some models suggest that temperatures there fell below freezing between 237 million and 174.1 million years ago have been controversial, so no one knows whether the reptile actually lived in a cold environment.
Olsen’s team’s findings could explain how dinosaurs continued to rule the planet after almost all large land and sea life in the tropics went extinct.
Fossil dating suggests that most medium- and large continental reptiles suddenly disappeared at the end of the Triassic period, when temperatures plummeted and decade-long volcanic eruptions filled the air with sulfur. But Olsen said that after this extinction event, medium- and large dinosaurs quickly appeared almost everywhere, and the adaptation of polar dinosaurs to the cold may explain the reason.
Olsen said the dinosaurs were prepared to respond when temperatures plummeted at the end of the Triassic period, feeding on polar vegetation and fending off the cold with insulating feathers. These dinosaurs then spread around the world during the Jurassic, replacing large, non-insulated reptiles that had become extinct.
The paper was recently published in Advances in Science. “The paper shows that our view of the dinosaur world is fundamentally wrong.” Olsen said dinosaurs were basically animals that adapted to the cold. (Source: China Science Daily, Li Muzi)
Related paper information:https://doi.org/10.1126/sciadv.abo6342