World's Greatest Mass Extinction Probably Helped Mammals Evolve, Researchers Say

Cynodont therapsids, close relatives of mammals, not only survived the world's greatest mass extinction, but also thrived in the new world, a new study has found. The research sheds light on life's ability to continue after cataclysmic events.

The mass extinction occurred about 252 million years ago. The ancient mammal-like creatures evolved about 225 million years ago and include small animals such as Megazostrodon from South Africa, Bienotherium from China and Morganucodon from England, according to a news release. Cynodonts are considered to be the missing link between reptiles and mammals. These creatures evolved jaw structure along with stirrup bones of the inner ear, similar to mammals.

The mammals in the present study had differentiated teeth- incisors, canines and molars along with a larger brain and fur. They were also warm-blooded animals which led to their success in the new environment. The study was conducted by researchers from University of Lincoln, UK, the National Museum in Bloemfontein, South Africa, and the University of Bristol, UK

The end-Permian mass extinction wiped out 70 percent of organisms living on land and another 90 percent of marine creatures. Researchers suggest that the features that helped the ancient mammals evolved gradually after the mass extinction.

"Mass extinctions are seen as entirely negative. However, in this case, cynodont therapsids, which included a very small number of species before the extinction, really took off afterwards and were able to adapt to fill many different niches in the Triassic - from carnivores to herbivores," said Dr Marcello Ruta, evolutionary palaeobiologist from the University of Lincoln's School of Life Sciences and lead author of the study.

"We saw that when a major group, such as cynodonts, diversifies, it is the body shape or range of adaptations that expands first. The diversity, or number of species, rises after all the morphologies available to the group have been tried out," co-author Professor Michael Benton, of the University of Bristol, said.

The study is published in the journal Proceedings of the Royal Society B.

According to the IUCN Red List, nearly 21,000 species, including conifers, freshwater shrimps, cone snails and the Yangtze Finless Porpoise, are about to go extinct. Data from studies conducted on ancient animals can help researchers understand how species cope with major changes in the ecosystem. Certain species that survive a dramatic change in the ecosystem get better resources in the future. They also have fewer competitors and develop new lifestyle and anatomical features. These changes help them adapt to changes in the environment.