250 million years ago, the extremely violent eruptions of several Siberian volcanoes sent billions of tons of gases and dust into the atmosphere, causing climate change that killed much of life. The episode is known as the Permian-Triassic mass extinction (also called the Great Dying) , and it has been the largest cataclysm of its kind in the history of the planet.
But there were animals that managed to survive. A study by paleontologists from the Utah Museum of Natural History and Utah State University has shown that a group of ancient mammals known as therapsids adapted to hostile new conditions and overcame bad drinking.
How they did it? According to the researchers, reducing their life expectancy and reproducing at earlier ages than their predecessors. Scientists have studied the growth patterns of these animals from well-preserved fossils from the Karoo, a semi-desert plateau in southern South Africa.
The remains belonged to specimens from before and after the Great Dying, which has made it possible to compare them and estimate their ages and survival rates. The work focused on the very abundant fossils of Lystrosaurus , a genus of therapsids that very successfully survived the Permian-Triassic extinction, after which they dominated terrestrial ecosystems for millions of years.
The average age of the found specimens of this animal that lived before the great disaster was 12-14 years; those of later had 2 or 3, which implies that after the cataclysm they reproduced more and more young. This change affected their anatomy: before the great extinction, they were the size of a small hippopotamus; behind her, that of a large dog, in part due to the alteration of his life expectancy.
Ecological models show that, by reproducing very young, Lystrosaurus would have increased its chances of survival by 40% in an unpredictable environment like the one that followed the Great Dying.
This phenomenon has also been documented in modern times: in the last century, the common or Atlantic cod was on the verge of extinction due to overfishing. The surviving specimens began to breed each time before and reduced their size as a tactic to escape their end.
Photo (Ken Angielczyk): Lystrosaurus specimen from the Albany Museum in Grahamstown, South Africa.
