The survival of ancient amphibian relatives of modern frogs after Earth’s most catastrophic mass extinction has long intrigued paleontologists. New research from the University of Bristol sheds light on why these amphibians, known as temnospondyls, thrived in the aftermath of the Permian-Triassic mass extinction, while many other species perished. Their ability to exploit freshwater ecosystems, which remained relatively stable compared to terrestrial environments, played a crucial role in their success. By feeding on diverse aquatic prey, they evaded the harsh conditions that wiped out nearly 90% of species on land and in the seas.
The Permian-Triassic mass extinction, which occurred 252 million years ago, remains the most devastating extinction event in Earth’s history. A combination of massive volcanic eruptions, global warming, acid rain, and oxygen depletion led to widespread collapse of ecosystems. The period that followed—the Triassic—witnessed a slow and uneven recovery of life. Scientists have long focused on understanding the survivors of this catastrophe and their adaptive strategies. Among these survivors, temnospondyls, an early group of amphibians distantly related to modern frogs and salamanders, stand out as one of the most successful.
A recent study titled The ecology and geography of temnospondyl recovery after the Permian—Triassic mass extinction, published in Royal Society Open Science, explores how temnospondyls managed to survive and even thrive in this extreme environment. Lead author Aamir Mehmood from the University of Bristol’s School of Biological Sciences highlights the importance of their generalist feeding strategy, which allowed them to consume a wide variety of prey. Unlike strictly terrestrial predators, which struggled with fluctuating and often insufficient food supplies, temnospondyls hunted in freshwater habitats, where food sources remained more consistent despite the unstable global climate.
The study involved a comprehensive examination of 100 different species of temnospondyls that lived throughout the Triassic. Researchers analyzed their body sizes, skull structures, and teeth morphology to understand their dietary habits and ecological roles. Surprisingly, they found that temnospondyls did not change significantly in size or feeding habits immediately after the extinction event. Some species remained small, feeding on insects and other invertebrates, while others were larger and specialized in hunting fish. Broad-snouted forms emerged as generalist feeders, capable of consuming a wide range of prey.
Dr. Suresh Singh, a co-author of the study, explained that despite the devastating environmental changes of the Early Triassic, temnospondyls maintained their ecological diversity. Another researcher, Dr. Armin Elsler, noted that while their diversity remained stable for the first few million years after the extinction, it expanded significantly about five million years later, before gradually declining. This temporary burst of diversity suggests that temnospondyls took advantage of ecological opportunities left by the mass extinction before competition from emerging terrestrial species became too intense.
The Early Triassic was marked by extreme climate instability, with frequent volcanic eruptions leading to prolonged periods of global warming, reduced oxygen levels, and widespread wildfires. These conditions created what scientists call a “tropical dead zone”, an area where life struggled to survive due to excessive heat and lack of resources. Many land-dwelling species perished, and even marine life suffered significant setbacks. However, temnospondyls managed to navigate this hostile world by moving between different climate zones.
Professor Mike Benton, a co-author of the study, highlighted how fossils of temnospondyls have been found in South Africa, Australia, North America, Europe, and Russia. This widespread distribution suggests that these amphibians were able to traverse the tropical dead zone when temperatures briefly cooled, allowing them to expand their range in search of better conditions. Their adaptability in different environments further contributed to their survival.
However, their reign was not permanent. As the Middle Triassic progressed, new groups of land-dwelling vertebrates, including the ancestors of dinosaurs and mammals, began to emerge and diversify. These new competitors, better suited for terrestrial life, gradually outcompeted temnospondyls, leading to their decline. While some species persisted into the Jurassic, their dominance faded, eventually giving way to the rise of modern amphibians.
The study underscores the resilience and adaptability of temnospondyls in the face of extreme environmental challenges. Their success highlights the importance of ecological flexibility in surviving mass extinctions—an insight that is relevant even today, as modern species face increasing environmental pressures due to climate change and habitat destruction.
Temnospondyls serve as a fascinating example of how some species can exploit unique ecological niches to survive when the world around them is collapsing. Their story is not just one of survival but also of eventual decline, a reminder that even the most adaptable species can be overtaken by evolutionary pressures over time. Understanding their journey helps scientists piece together the complex puzzle of life’s resilience and the ever-changing nature of Earth’s ecosystems.
More information: Aamir Mehmood et al. Macroecology of temnospondyl recovery after the Permian-Triassic mass extinction, Royal Society Open Science (2025). DOI: 10.1098/rsos.241200. royalsocietypublishing.org/doi/10.1098/rsos.241200