The end-Permian mass extinction, 252 million years ago, was the largest, wiping out up to 90% of species. Researchers have focused on the survivors and their fate in the following Triassic period.
One mystery is how a major group of amphibians called temnospondyls survived and thrived. These early land vertebrates were important in the Carboniferous and Permian periods but didn’t seem well-suited to survive in the challenging post-extinction world. Did they have special adaptations or occupy specific areas?
University of Bristol academics explored temnospondyl success in the Triassic by comparing their functional ecomorphology and palaeogeographic distributions. They found that these ancient frog relatives survived by feeding on freshwater prey that evaded terrestrial predators.
The study found that these amphibians were successful because they could eat various prey, even with many environmental changes during the Triassic period. Freshwater habitats provided stable food sources, helping them thrive, while land predators struggled with limited and unstable food supplies.
Lead author Aamir Mehmood from Bristol’s School of Biological Sciences explained, “These predators ate fish and other prey and were mainly linked to water, like modern frogs and salamanders. We know that climates then were hot, especially after the extinction event. How could these water-loving animals have been so successful?”
During the Early Triassic, frequent volcanic eruptions led to long periods of global warming, drying out the land, lowering oxygen levels, acid rain, and widespread wildfires. These harsh conditions made the tropics uninhabitable for animals, creating a “tropical dead zone” that greatly affected the distribution of both marine and land organisms.
Co-author Dr. Suresh Singh said, “We collected data on 100 temnospondyls that lived throughout the Triassic and wanted to see how their ecologies changed. We measured their body sizes and features of the skulls and teeth that tell us about function.”
Dr. Armin Elsler added, “Much to our surprise, they did not change much through the crisis. The temnospondyls showed the same range of body sizes as in the Permian, some small and feeding on insects, and others larger. Larger forms included long-snouted animals that trapped fishes and broad-snouted generalist feeders. What was unusual was how their diversity expanded about 5 million years after the crisis and then dropped back.”
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Due to intense global warming in the first five million years of the Triassic, life on land and in the sea moved away from the tropics to escape the heat.
Professor Mike Benton explained that temnospondyls could, surprisingly, cross the tropical dead zone. Fossils have been found in South Africa, Australia, North America, Europe, and Russia, suggesting that temnospondyls could move through the tropics during cooler periods.
Aamir added that their success in the Early Triassic didn’t last. They likely survived the hot conditions by needing little food, eating various prey, and hiding in small water bodies. However, as dinosaurs and mammals started diversifying in the Middle Triassic, temnospondyls began declining.
Journal Reference
- Mehmood Aamir, Singh Suresh A., Elsler Armin and Benton Michael J. 2025The ecology and geography of temnospondyl recovery after the Permian–Triassic mass extinction. R. Soc. Open Sci. 12241200. DOI: 10.1098/rsos.241200
