How amphibians survived Earth’s deadliest mass extinction

Life on Earth has faced several extinction events, but none were as devastating as the end-Permian mass extinction 252 million years ago. Nearly 90% of all species vanished, yet some amphibians managed to survive.

This catastrophe reshaped ecosystems, forcing the remaining species to adapt to extreme conditions. Among these survivors were ancient amphibians called temnospondyls, distant relatives of modern frogs and salamanders.

Scientists from the University of Bristol have uncovered how these early amphibians endured the extinction crisis.

The findings, published in Royal Society Open Science, reveal that temnospondyls thrived by feeding on freshwater prey, which remained stable while land-based food sources dwindled.

Their adaptability helped early amphibians survive a world marked by climate chaos and environmental upheaval.

How amphibians survived extinction

The period following the end-Permian extinction was marked by drastic environmental shifts. Massive volcanic eruptions led to rising global temperatures, acid rain, and widespread wildfires.

Many terrestrial species struggled to find food as plant and animal populations plummeted. However, freshwater ecosystems remained relatively stable, providing a refuge for adaptable predators like temnospondyls.

“One of the great mysteries has been the survival and flourishing of a major group of amphibians called the temnospondyls,” said 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 the 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?”

Scientists believe that the feeding habits of amphibians played a crucial role in preventing their extinction. Unlike land-dwelling predators, which relied on an unstable food supply, temnospondyls could hunt a variety of freshwater creatures, ensuring their survival even when environmental conditions changed.

Features of early amphibians

“We collected data on 100 temnospondyls that lived throughout the Triassic and wanted to look at how their ecologies changed. We measured their body sizes and features of the skulls and teeth that tell us about function,” noted co-author Dr. Suresh Singh.

“Much to our surprise, we found that they did not change much through the crisis,” added 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. What was unusual though was how their diversity of body sizes and functional variety expanded about 5 million years after the crisis and then dropped back.”

Surviving the tropical dead zone

Due to extreme global warming in the Early Triassic, many species moved away from the tropics. However, temnospondyls managed to cross these inhospitable regions.

“Our work shows that the temnospondyls, unexpectedly, were able to cross the tropical dead zone,” said Professor Mike Benton.

“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 decline of early amphibians

Their early success highlights the resilience of amphibians, showing how adaptability can determine survival in extreme environments. However, Mehmood pointed out that the amphibians’ rapid success in the Early Triassic was short-lived.

“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. But when the ancestors of dinosaurs and of mammals began to diversify in the Middle Triassic, the temnospondyls began their long decline.”

The dominance of temnospondyls faded as the new competitors emerged, leading to their eventual extinction.

A legacy of resilience

Temnospondyls may have disappeared, but their story highlights how adaptability shapes survival. Their ability to endure extreme environmental changes for millions of years demonstrates the importance of flexible feeding strategies and ecological diversity.

The history of temnospondyls also provides insight into how modern amphibians might respond to environmental challenges.

As climate change alters habitats today, species with broad diets and adaptable lifestyles may have the best chance of survival, just as the temnospondyls did millions of years ago.

The study is published in the journal Royal Society Open Science.

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