This is how life exploded on Earth after the Great Permian extinction.

In an investigation published these days in the journal Frontiers in Earth Sciencescientists reveal that predators became more aggressive and prey quickly adapted to find new ways to survive. On land, the ancestors of mammals and birds became warm-blooded and could move faster.

252 million years ago, at the end of the Permian period, there was a devastating mass extinction that wiped out nearly all life on Earth’s surface. But this episode was followed by one of the most extraordinary moments in his life’s history. And this The Triassic period, 252 to 201 million years ago, marked an incredible rebirth of life on land and in the oceans.

“Everything accelerated,” says Professor Michael Benton of the University of Bristol’s School of Earth Sciences, lead author of the new study. “Today, there is a big difference between birds and mammals on the one hand and reptiles on the other. Reptiles are cold-blooded, which means they don’t produce much body heat on their own, and although they can produce it quite effectively, they have no heat energy and I can’t live in cold,” said Professor benton

“The same thing happened in the oceans” said Feixiang Wu of the Institute of Vertebrate Paleontology in Beijing. “Following the mass extinction at the end of the Permian, fish, lobsters, gastropods and starfish exhibited new, more efficient hunting styles. They were faster, more agile and stronger than their ancestors.”

Widespread changes in the fauna

Wu has studied incredible new assemblages of fossil fish from China’s Triassic period, and among them are many species of predators that show how. new hunting methods emerge earlier than previously thought. He found sharks and long fish in the modern style. Saurichthysvery common all over the world and hunted by ambush. This one-metre-long fish lurked in the shallow, turbid seas, burrowing in to snatch prey of all kinds with its toothy jaws.

Dr. “Other Triassic fish from China were adapted to crack shells,” Wu said. “A few large groups of fish and even some reptiles became shell breakers with large rows of teeth. We even found the world’s oldest flying fish, and that was probably to escape new predators.”

Revolutionary changes took place on the mainland as well. Late Permian reptiles were generally slow-moving and, like modern lizards, used a type of splayed stance with the limbs protruding to the sides. When walking, they probably usually move slowly and quickly, can run or breathe, but not both at the same time. This limited his endurance.

“Biologists have long debated the origins of endothermy, or warm blood, in birds and mammals,” said Professor Benton. “We can trace their ancestry back to the Carboniferous more than 300 million years ago, and some researchers have recently suggested that they were endothermic at that time. Others say they were only endothermic in the Jurassic, say 170 million years ago. But it’s all in their bones. Evidence from studying the chemistry of cells and even their bones suggests that both groups became warm-blooded after the great mass extinction in the early Triassic, at the end of the Permian.”

The origins of endothermy in birds and mammals in the early or middle Triassic are inferred by two other changes: ancestral During this period, they mainly adopted an upright stance. Modern dogs, like horses and birds, could take longer strides by standing on their limbs. This probably goes hand in hand with some endothermy to allow them to act quickly and for longer.

Second, the early and middle Triassic ancestors of birds and mammals they had some kind of isolation, such as feathers in the mammalian line or feathers in the bird line.. If this is true, and new fossil discoveries seem to confirm it, all the evidence points to major changes in these reptiles as the world rebuilt itself after the mass extinction at the end of the Permian.

‘arms race’

“Overall, animals on land and in the oceans were evolving by using more energy and moving faster,” says Professor Benton. “Biologists call such processes ‘arms races’ compared to the Cold War. As one side gets faster and warmer, the other side has to do it too.. This affects competition between plant eaters and competition between predators. It also refers to predator-prey relationships: if the predator is faster, the prey will do so to escape.”

Dr. “The same thing happened underwater,” Wu said. “As predators became faster, more agile, and smarter at attacking their prey, these other animals had to develop defenses as well.. Some have had thicker shells, have grown spines, or have stepped themselves up to help them escape.”

“These are not new ideas,” says Benton. “What’s new is that we’re discovering this now. It seems that all of this was happening at the same time, throughout the Triassic.”

“Of course the mass extinctions were terrible news for all the victims. But in this case, the mass clearing of ecosystems has provided multiple opportunities for the biosphere to rebuild itself, and it has done so with greater momentum than before the crisis,” he added.

Reference Work: DOI: 10.3389/feart.2022.899541

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