When the world nearly ended 252 million years ago, a unique group of amphibians not only survived but thrived in the aftermath of the most devastating mass extinction in Earth’s history. New research reveals their secret weapon: an ability to feed on freshwater prey that had escaped the ecological devastation happening on land.
The end-Permian mass extinction wiped out up to 90% of species on the planet, creating a scorched landscape where few creatures could survive. Yet against the odds, a group of ancient amphibians called temnospondyls managed to flourish, diversifying rapidly in what should have been an inhospitable world.
“One of the great mysteries has been the survival and flourishing of a major group of amphibians called the temnospondyls,” explained lead author Aamir Mehmood from Bristol’s School of Biological Sciences. “These were predatory animals that fed on fishes and other prey, but were primarily linked to water, just like modern amphibians such as frogs and salamanders. We know that climates then were hot, and especially so after the extinction event. How could these water-loving animals have been so successful?”
The study, published March 5 in the journal Royal Society Open Science, analyzed 100 temnospondyl species spanning the entire Triassic period—the time that followed the great extinction. By measuring body sizes and examining skull and tooth features that reveal feeding function, the researchers uncovered how these animals adapted to a world in crisis.
“Much to our surprise, we found that they did not change much through the crisis,” said co-author Dr. Armin Elsler. “The temnospondyls showed the same range of body sizes as in the Permian, some of them small and feeding on insects, and others larger. These larger forms included long-snouted animals that trapped fishes and broad-snouted generalist feeders.”
The Early Triassic was a hellscape of repeated volcanic activity that triggered global warming, acid rain, reduced atmospheric oxygen, and widespread wildfires. Conditions were so extreme that tropical regions became virtually uninhabitable for many species—a phenomenon scientists call the “tropical dead zone.”
Yet the temnospondyls managed to navigate this apocalyptic world. Professor Mike Benton explained: “Our work shows that the temnospondyls, unexpectedly, were able to cross the tropical dead zone. Fossils are known from South Africa and Australia in the south, as well as North America, Europe and Russia in the north. The temnospondyls must have been able to criss-cross the tropical zone during cooler episodes.”
The research team found that these amphibians thrived because they were ecological generalists with a broad diet, allowing them to exploit whatever food resources were available as environments fluctuated wildly. Their link to water bodies gave them access to relatively stable food sources when land ecosystems were devastated.
Far from the specialized physiologies we might expect from disaster survivors, temnospondyls maintained varied feeding styles throughout the crisis. Some had long, narrow snouts specialized for catching fish, while others had broader skulls for consuming a wider variety of prey—similar to the difference between modern gharials and crocodiles.
This versatility proved crucial as ecosystems rebuilt themselves following the mass extinction. While strictly terrestrial predators struggled with meager, unpredictable food sources, temnospondyls enjoyed the relative stability of freshwater habitats.
In the aftermath of the extinction, temnospondyls underwent a remarkable burst of diversification, reaching their peak in the Early Triassic before beginning a long decline. By studying the morphological features of their skulls over time, researchers discovered that their ecological variety reached its zenith about 5 million years after the crisis before dropping back.
The research offers insights into how some animals survived while so many others perished. Rather than evolving new specialized adaptations, temnospondyls succeeded by maintaining ecological flexibility and exploiting habitats that provided some protection from the extreme conditions.
“They coped with the hot conditions probably by having a low requirement for food, by being able to eat most prey animals, and by hiding in sparse water bodies,” concluded Mehmood. “But when the ancestors of dinosaurs and of mammals began to diversify in the Middle Triassic, the temnospondyls began their long decline.”
The findings contribute to our understanding of extinction and recovery dynamics, showing how some groups can thrive in the wake of mass extinctions by exploiting ecological opportunities rather than developing novel adaptations.
Despite their early Triassic success, the temnospondyls would ultimately fade as new vertebrate groups emerged. Yet their story remains relevant today, as it demonstrates how ecological versatility and habitat selection can determine which species survive when climates change dramatically.
For paleontologists, these ancient amphibians offer a window into evolutionary responses to global catastrophe. As our planet faces its own biodiversity crisis, understanding how some organisms weathered Earth’s greatest apocalypse may provide clues about ecological resilience in the face of environmental upheaval.