(ORDO NEWS) — While we traditionally think of dinosaurs as cold-blooded creatures that lived in warm, “greenhouse” climates, recent data are increasingly turning this model on its head.
Now scientists have paleoclimatic evidence that the dinosaur empire, which arose at the border of the Triassic and Jurassic periods, was founded during a time of global cooling, and it was built by warm-blooded reptiles.
Approximately 200 million years ago, at the end of the Triassic period , the Earth suffered another mass extinction that destroyed the ancient reptiles and giant amphibians.
This “cleared a foothold” for the dinosaurs, during the first few million years of the Jurassic they spread widely throughout the planet and began to play a leading role in all terrestrial ecosystems.
It was long believed that the world of dinosaurs was built in a hot, arid climate that only softened in the early Jurassic with the breakup of the supercontinent Pangaea.
However, evidence has now been found that the first “terrible lizards” did not live in the withering deserts, but in the polar regions of the planet, where they regularly encountered snow and frost.
Dinosaurs first appeared on Earth in the Middle Triassic, about 231 million years ago, in temperate latitudes, and about 215 million years ago they already left their traces in the polar regions of the planet.
While the warm regions were dominated by ancient reptiles such as rhynchosaurs and coolotars , at the poles dinosaurs were able to dominate ecosystems.
How did they manage to do it? Given the high concentrations of carbon dioxide in the atmosphere throughout the Triassic (about five times higher than the current level), scientists believed that the climate was too hot for frosts, and even at the North Pole the temperature, if lowered due to lack of sunlight, then not as much as today.
However, at the end of the Triassic period, massive volcanic eruptions began, associated with the upcoming split of Pangea.
This caused a sharp rise in carbon dioxide concentrations and, more importantly, a massive release of sulfur aerosols into the atmosphere, which led to a global winter.
Evidence of this was found in northern China: having studied deposits about 206 million years old, scientists found the remains of dinosaurs (despite the fact that in the Triassic the place of study was located in the Arctic) and traces of the formation of ice masses, preserved in the form of a large number of pebbles.
Since there was nothing for small stones to do away from the coastline, the only plausible explanation for their appearance is the formation of a massive ice floe, which raked in part of the underlying rock; in modern times, such deposits of pebbles are typical of places where an ancient glacier once passed.
Thus, primitive dinosaurs, covered with simple feathers and having a high metabolic rate, survived in the polar regions of the planet until volcanic eruptions and global cooling destroyed the ancient Triassic reptiles. After that, the “terrible lizards” were able to spread throughout the Earth.
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