Triassic Revolution: Animals grew back faster and smarter after mass extinction

The diversification of the saurichthyiform fish (“lizard fish”) in the Middle Triassic of southern China (Eastern Paleo-Tethys), due to the establishment of a complex stratified marine ecosystem (or marine fish communities) with intensive interactions between predators and prey along the food chains. Credit: Feixiang Wu

Paleontologists in the UK and China have shown that the natural world rebounded vigorously after the extinction of the late Permian.

In a review, published today in the magazine Frontiers in Earth Science, scientists reveal that predators became nastier and that prey animals quickly adapted to find new ways to survive. On land, the ancestors of mammals and birds became warm-blooded and could move faster.

At the end of the Permian period, 252 million years ago, there was a devastating mass extinction, when almost all life became extinct, and this was followed by one of the most extraordinary times in the history of life. The Triassic, from 252-201 million years ago, marks a dramatic rebirth of life on land and in the oceans, and was a time of massively soaring energy levels.

“Everything went faster,” said Professor Michael Benton of the University of Bristol School of Earth Sciences, the lead author of the new study.

“Nowadays there is a huge difference between birds and mammals on the one hand and reptiles on the other. Reptiles are cold-blooded, meaning they don’t generate much body heat on their own, and although they can forage around quite quickly, they have no stamina, and they can’t live in the cold,” said Prof Benton.

“It’s the same in the oceans,” says Dr. Feixiang Wu of the Institute of Vertebrate Paleontology in Beijing. “After the mass extinction at the end of the Permian, the fish, lobsters, gastropods and starfish showed annoying new hunting styles. They were faster, spicier and stronger than their ancestors.”

dr. Wu has studied amazing new collections of fossil fish from the Triassic of China, and these include many species of predators showing how new hunting methods appeared earlier than thought. He has found sharks in modern style, and the long fish Saurichthys, which was common worldwide and was an ambush hunter. This meter-long fish lurked in murky shallow seas and darted forward to grab all sorts of prey in its serrated jaws.

“Other Triassic fish from China were adapted to crushing shells,” said Dr. wu. “Several large groups of fish, and even some reptiles, became shell-breakers, with great pavements of teeth. We even found the world’s oldest flying fish, and this was probably to escape the new predators.”

There were also revolutionary changes on the land. The newest Permian reptiles generally moved slowly and used a kind of sprawling stance, like modern lizards, with limbs sticking out to the side. When they walked, they probably generally moved slowly and with speed they could run or breathe, but not both at the same time. This limited their stamina.

“Biologists have long debated the origin of endothermy, or warm-bloodedness, in birds and mammals,” said Prof. Benton. “We can trace their ancestors back to the Carboniferous, over 300 million years ago, and some researchers have suggested recently that they were endothermic then. Others say they only became endotherm in the Jurassic, say 170 million years ago. But all sorts of things.” Some sort of evidence from studying the cells in their bones, and even the chemistry of their bones, suggests that both groups became warm-blooded in the wake of the great late Permian mass extinction, early in the Triassic.”

The origin of endothermy in birds and mammals in the Early to Middle Triassic is suggested by two other changes: their ancestors were mainly upright during that time. Standing tall on their limbs, like modern dogs, horses, and birds, allowed them to make bigger strides. This probably goes hand in hand with a degree of endothermia to allow them to move quickly and for extended periods of time.

Second, it now appears that the early and middle Triassic bird and mammal ancestors had some form of insulation, hairs in the mammalian line, feathers in the bird line. If this is true, and new fossil evidence seems to confirm this, 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.

“Overall, animals on land and in the oceans were accelerating, using more energy and moving faster,” said Professor Benton. “Biologists call these kinds of processes ‘arms races’, referring to the Cold War. As one side accelerates and becomes more warm-blooded, the other side must do the same. This affects competition between herbivores or competition between predators. It also refers to predator. -prey relationships – as the predator speeds up, so does the prey to escape.”

“It was also the same underwater,” said Dr. Wu. “As the predators got faster, faster and smarter at attacking their prey, these animals had to develop defenses. Some got thicker shells or developed spines, or became faster themselves to help them escape.”

“These aren’t new ideas,” Benton says. “What’s new is that we’re now discovering that they all happened around the same time, through the Triassic. This highlights some kind of positive aspect of mass extinctions. Mass extinctions, of course, were terrible news for all the victims. But the massive clean-up of ecosystems gave in. In this case, huge numbers of opportunities for the biosphere to rebuild itself, and that happened at a higher octane than before the crisis.”


The world’s largest mass extinction caused switch to warm-bloodedness


More information:
Michael J. Benton et al, Triassic Revolution, Frontiers in Earth Science (2022). DOI: 10.3389/feart.2022.899541

Provided by the University of Bristol

Quote: Triassic revolution: Animals grew back faster and smarter after mass extinction (2022, June 20) retrieved June 21, 2022 from https://phys.org/news/2022-06-trias-revolution-animals-grew-faster.html

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