How Reptiles Conquered the World


Climate change is shaping the way animals evolve, whether their appearance Where to behave. Similarly, global warming that happened millions of years ago helped reptiles evolve faster, diversify and take over the world, a new study has found.

Researchers have long believed that the extinction of some of our mammalian ancestors at the end of the Permian period (about 252 million years ago) reduced competition for food and habitats, ultimately allowing reptiles to thrive. in the following Triassic period. But the rise of reptiles hasn’t just translated into less competition, according to a recent study. Reptiles began to thrive much earlier, at least 270 million years ago, thanks to intense episodes of global warming.

Harvard researchers published their findings in the journal Scientists progress.

The period between 300 and 200 million years ago is a very interesting period to see how different species evolved, because this era saw several successive climate change events, explained Tiago Simões, lead author of the study and postdoctoral researcher at Harvard University.

“It was the most difficult period in the history of the planet. It is linked to not one, but two major mass extinctions,” Simões told Mashable.


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Of the five mass extinction events Earth has experienced so far, the Permian-Triassic extinction that occurred around 250 million years ago is arguably the most significant. It wiped out nearly 90% of life on the planet. How the reptiles survived this mass extinction event was the looming question that Simões and his Harvard team chose to research.

“It was the most difficult period in the history of the planet.”

The research team used reptile fossil records from 20 countries for the study. While seeking to understand how reptiles survived mass extinctions, researchers found that reptiles had established a foothold in various places, in water and on land, long before the extinction events began. These animals have adopted unique adaptations that have enabled them to withstand hot temperatures, making them evolutionary winners.

Warmer climates, changing bodies

Reptiles were already developing new body plans that likely helped them cope well with the relatively sudden and drastic conditions that emerged during extinction events, Simões told Mashable. The rate at which reptiles evolved was faster compared to the mammalian evolutionary precursor, called “synapsids”, which existed at that time, he said.

Not all reptile species have reacted to global warming in the same way. Reptiles are cold-blooded animals that largely depend on their environment to regulate body heat. Natural selection favors small animals in hot climates because small creatures release their body heat more easily than larger ones. This adaptation helped small reptiles to succeed, evolve and diversify faster.

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According to the study, the larger reptiles could have used two strategies to combat extreme temperatures. They may have ventured into the water or migrated to colder regions. Either way, a cooler environment would have helped larger reptiles tolerate warmer climates better.

One line of small-sized reptiles, the lepidosaurs, however, evolved slowly. The animals (which included snakes and lizards) were already very small, and they didn’t have as much environmental pressure to change their bodies to adapt to the heat. They kept their original body plan. “Basically it worked for them,” Simões explained.

“This is a question that has fascinated researchers for a long time.”

This study addresses the interesting point of explaining how different groups of reptiles responded differently to climate change, said evolutionary ecologist Davide Foffa, who was not part of this recently published study. “This is a question that has fascinated researchers for a long time,” he said.

Climate change threatens more than 20% of reptile species with extinction, according to a World Reptile Assessment.
Credit: Brett Monroe Garner/Getty Images

But the results of this study cannot be easily applied to how reptiles are adapting to climate change today, Simões said. The impact of climate change on reptile evolution is different now. The rate of heating trapping carbon dioxide entering the atmosphere today is higher than it has been for tens of millions of years, and the increase is likely higher than rates seen before. the Permian extinction, added Simões.

Many animals today will not have time to adapt to such significant warming. Climate change threatens 20 percent endangered reptile species, according to a Global Reptile Assessment released this year.

“It’s quite alarming,” Simões said.


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