You have one additional motivation to be concerned about global warming if you are devoted to mammals in the face of ravaging reptiles. According to recent research, rather than two catastrophic extinctions as previously believed, a prolonged period of warming caused reptiles, including the dinosaurs, to outlive mammals and human ancestors.
Reptile evolution accelerated throughout the early Triassic period. Archosaurs, for example, began to rule the landscape until being displaced by their fellow reptiles, the dinosaurs. These occurrences came after the Permian-Triassic extinction event (PTE), also known as the Great Dying, during which an estimated 86 percent of all animal species died extinct and was the largest mass extinction in Earth’s history.
Paleontologists believe that the PTE and a lesser catastrophe nine million years earlier contributed to the reptile takeover. Mass extinctions open up new possibilities for survival. Undoubtedly, significant reptile families that are now extinct as well as the earliest crocodiles, lizards, and turtles all appeared in the Triassic. The origins of the reptiles’ emergence, though, may have been earlier, in late-Permian temperature variations, according to a paper in Science Advances.
Only since an asteroid cleared the path for us 66 million years ago have mammals dominated the animal kingdom on Earth. But during the Permian period, our predecessors, the synapsids, took a different course. It seems to reason that both the beginning and conclusion of the reptile epoch had extinction events. The causes of the PTE are hotly contested, but there is no doubt that the synapsids suffered greatly.
The study does point out that there was an increase in new reptile species prior to the extinctions, even though the greatest rate of reptile diversification occurred afterward. The timing of their appearance was also not coincidental.
“We discovered that these times of fast reptile evolution were closely related to rising temperatures. According to main scientist Dr. Tiago R. Simes of Harvard University, “almost all reptiles were changing far quicker than they ever had before. Some groups changed tremendously fast and some less fast.
Professor Stephanie Pierce, a co-author, pointed out that occurrences of warming were not only accompanied by an increase in the number of new species, but also in the diversity of body shapes and ecological niches occupied. According to Pierce, “This process began at least 270 million years before the Permian-Triassic extinction, demonstrating that the diversification of reptile body plans was not initiated by the P-T extinction event as previously thought, but rather started tens of millions of years before that.”
Reptiles are much better adapted to hot warm regions than cold ones because they can’t control their own body temperatures, yet some dinosaurs were able to reheat their blood enough to live in the poles. The authors believe that it is not as straightforward as saying that higher heat equals more reptiles.
Simes claimed that smaller-bodied reptiles could better exchange heat with their surroundings. Since they were much smaller than other species of reptiles and were very similar to their contemporary cousins, the early lizards and tuataras were better suited to withstand sudden changes in temperature. The much larger progenitors of crocodiles, turtles, and dinosaurs had to quickly alter their bodies in order to adapt to the changing environmental conditions since they could not dissipate heat as easily.
As a result, the Permian’s relatively quick changes suited small reptiles, whereas the early Triassic’s constant heat benefited larger ones. The tropics became so hot during the warmest periods of the Permian that reptiles were unable to grow very large there without migrating into the oceans.
Because there are few land records, the authors believe this early reptile diversification has gone unnoticed. Due to their greater abundance, marine fossils are the subject of studies on the great extinction. To address this, the paper employed the largest database ever created on the emergences and extinctions of early reptiles, synapsids, and ancestors.
