The Triassic-Jurassic extinction gave way to the dinosaurs 200 million years ago. In question, levels of CO2 which have caused many extreme climatic phenomena.
Long before the collision of a meteorite with the Earth 66 million years ago, another massive extinction took place: that of the Triassic-Jurassic. Reptiles then populated the Earth for the most part. Especially during the Trias, which started 251 million years ago, and ended 202 million years ago, when a reversal occurred. A “short” geological period of one million years saw the extinction of more than three quarters of the terrestrial and marine species on the planet.
Why ? The main reason, CO levels2 high, and their consequences. The average level on Earth was 2,000 ppm, nearly five times the current concentration. Extreme weather events have resulted, such as volcanic eruptions several hundred years old. They in turn raised CO levels2, causing deadly temperature spikes and ocean acidification, making them unlivable. But a new study published in the journal Science Advances has just added a stone to the building: in addition to extremely high temperatures, the volcanic eruptions also caused volcanic winters mortals.
The dinosaurs accustomed to the cold survived
Appearing about 231 million years ago, dinosaurs mainly populated the far north until the Triassic-Jurassic extinction. Insulated from the cold thanks to their primitive feathers, they survived the winters caused by eruptions: aerosols sulphurous, spat out by the volcanoesdeflected the light sun for one or even several decades, and caused these volcanic winters. The researchers deduced this scenario from excavations in the Junggar Basin in northeast China. They found there not only dinosaur footprints, but also rock fragments from ancient glaciers. “Dinosaurs Were There During The Triassic Under The Radar All The Timeconcluded Paul Olsen, first author of the study and geologist at the university of columbia. The key to their eventual dominance was very simple. They were basically cold-adapted animals. When it was cold everywhere, they were ready, and the other animals were not. »
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