While we have traditionally thought of dinosaurs as cold-blooded animals living in warm "greenhouse" climates, recent data increasingly overturns this model. Scientists now have paleoclimate evidence that the dinosaur empire that originated at the junction of the Triassic and Jurassic periods was built by warm-blooded reptiles during a period of global cooling.
Early predatory dinosaurs preyed on early mammals for lunch: the two evolutionary lines emerged at about the same time, but their fates were very different
About 200 million years ago, at the end of the Triassic, Earth suffered Another mass extinction, destroying ancient reptiles and giant amphibians. This "cleared a foothold" for the dinosaurs, which spread widely across the Earth during the first few million years of the Jurassic and began to play a dominant role in all terrestrial ecosystems .
It has long been thought that the world of dinosaurs was built in a hot, dry climate that changed with the breakup of the supercontinent Pangea in the early Jurassic.soft. However, evidence has now been found that the first "terrible lizards" lived not in blighted deserts, but in the Earth's polar regions, where they regularly encountered snow and frost.
Dinosaurs first appeared on Earth in the mid-Triassic period, about 231 million years ago, in temperate zones, and they have left traces in the Earth's polar regions about 215 million years ago. While warmer regions were dominated by ancient reptiles such as Rhinosaurus and Coolosaurus, at the poles dinosaurs were able to dominate the ecosystem.
How do they do it? Given the high concentrations of carbon dioxide throughout the Triassic atmosphere (about five times higher than current levels), scientists believe the climate was too hot for frost to form, even in the Arctic. If temperatures were lowered due to a lack of sunlight, then the climate would be Not as much as today.
However, at the end of the Triassic, massive volcanic eruptions began, which were related to the upcoming breakup of Pangea. This results in a sharp rise in carbon dioxide concentrations and, more importantly, a massive release of sulfur aerosols into the atmosphere, resulting in global winters.
Pangaea shortly before its extinction: Apparently most discoveries of early dinosaurs are restricted to temperate and polar latitudes, while in the tropics they were few and small
Evidence of this has been found in northern China: after studying about 206 million After the sediments were deposited years ago, scientists found the remains of dinosaurs (although during the Triassic period, the study site was located in the Arctic) and traces of ice formation, preserved in the form of massive pebbles.
Since the small rocks have nothing to do away from the shoreline, the only reasonable explanation for their appearance is the formation of a giant ice floe that tilted part of the underlying rock. In modern times, this pebble deposit is typical of places where ancient glaciers once passed.
So primitive dinosaurs, covered in simple feathers and with high metabolic rates, survived in Earth's polar regions until volcanic eruptions and global cooling destroyed the ancient Triassic reptiles. After that, the "terrible lizards" were able to spread across the earth.
The research was published in the journal Scientific Advances .
