Credit: Olsen et al., Science Advances, 2022ĭinosaurs are thought to have first appeared during the Triassic Period in temperate southerly latitudes about 231 million years ago, when most of the planet’s land was joined together in one giant continent geologists call Pangaea. Red area at the top is the Junggar Basin, now in northwest China.
Evidence of early dinosaurs has been found in the indicated areas most species were confined to the high latitudes, and those few nearer the tropics tended to be smaller. The supercontinent of Pangaea 202 million years ago, shortly before the Triassic-Jurassic Extinction. Dinosaurs, which had already adapted, survived the evolutionary bottleneck and spread out. The authors of the study explain that during the extinction, cold snaps already happening at the poles spread to lower latitudes, killing off the cold-blooded reptiles. The telltale indicators are dinosaur footprints along with odd rock fragments that only could have been deposited by ice. However, new research turns the idea of heat-loving dinosaurs on its head: It presents the first physical evidence that Triassic dinosaur species, which were a minor group largely relegated to the polar regions at the time, regularly endured freezing conditions there. We know that the world was generally hot and steamy during the Triassic Period, which preceded the extinction, and there were similar conditions during the following Jurassic, which kicked off the age of dinosaurs. What caused the so-called Triassic- Jurassic Extinction, and why did dinosaurs thrive when other creatures perished? But there was a far more mysterious and less discussed previous extinction: the one 202 million years ago, which wiped out the big reptiles who up until then ruled the planet, and apparently cleared the way for dinosaurs to take over. Many of us are familiar with the popular theory of how the dinosaurs died 66 million years ago: in Earth’s violent collision with a meteorite, followed by a global winter caused by dust and debris choking the atmosphere.
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Credit: Painting by Larry Felder Thriving in a Series of Sudden Global Chills That Killed Competitors A new study says dinosaurs survived because they were already adapted to freezing conditions at high latitudes. With a lava flow in the distance, a primitively feathered theropod dinosaur carries off a mammalian victim during a snowy volcanic winter caused by massive eruptions during the Triassic-Jurassic Extinction.