When discussing mass extinction events, the most common one that comes to mind is the asteroid impact that led to the extinction of dinosaurs around 66 million years ago. However, the Cretaceous–Paleogene extinction event was not the most severe loss of life in Earth’s history. That title belongs to the Permian-Triassic extinction, also known as the Great Dying. This event, which occurred approximately 252 million years ago, wiped out 80 to 90 percent of all species on Earth, completely altering the planet’s biosphere.
Despite this catastrophic event, some species managed to survive. One such group was the primitive amphibians known as temnospondyls. These creatures may have survived the Great Dying by consuming freshwater prey that larger predators couldn’t access and by being adaptable eaters. These new findings are outlined in a study published on March 4 in the journal Royal Society Open Science.
Around 250 million years ago during the Early Triassic period, nearly constant volcanic activity resulted in prolonged periods of global warming, arid conditions, decreased oxygen levels in the atmosphere, mega El Niños, acid rain, and wildfires. The environment became so hostile that animal life disappeared from the tropics completely. This led to a tropical dead zone that affected the distribution of marine and terrestrial organisms worldwide. Despite these challenges, some organisms like sharks, horseshoe crabs, and temnospondyls managed to survive.
The study sheds light on the survival and success of a significant amphibian group, the temnospondyls. These predators primarily fed on fish and other prey, similar to modern amphibians. The study’s co-author, Aamir Mehmood, an evolutionary biologist at the University of Bristol, pondered on how these water-loving animals thrived in the hot post-extinction climate.
To unravel this mystery, Mehmood and his team analyzed fossil data from 100 temnospondyls that lived during the Triassic period. They examined how their ecologies evolved by studying their skull structures, teeth, and body sizes to understand their functionalities.
Surprisingly, the temnospondyls did not undergo significant changes during the crisis. They maintained a range of body sizes similar to those in the earlier Permian period. Some were small insect feeders, while others were larger predators. The larger temnospondyls played a crucial role in their survival.
The study reveals that the success of temnospondyls was attributed to their generalist feeding habits. They could adapt to environmental changes by consuming a variety of prey and hiding in sparse water bodies. This adaptability allowed them to survive the extreme conditions of the Early Triassic period.
However, this success was short-lived as the temnospondyls began to decline by the Middle Triassic, coinciding with the diversification of mammal and dinosaur ancestors.
Despite their eventual extinction around 120 million years ago, temnospondyls, with no living descendants, are considered an important evolutionary link to modern amphibians by some evolutionary biologists. Studying these ancient periods can provide insights into how contemporary amphibians like frogs, salamanders, and toads may cope with present environmental challenges, as amphibians remain one of the most threatened animal groups due to diseases and climate change.
