How do you survive a mass extinction event? It just may be all about living fast and dying young. Scientists have discovered that the survivors of mass extinction events had a few traits in common.
About 250 million years ago, a series of Siberian volcanoes erupted. This, in turn, sent Earth into the greatest mass extinction event of all time. As a result of this event, billions of tons of carbon were propelled into the atmosphere, altering the Earth's climate.
In this latest study, researchers decided to see what traits allowed some species to survive this event while others completely vanished. The researchers paid special attention to the genus Lystrosaurus due to its success in surviving the Permo-Triassic extinction. In fact, this genus dominated ecosystems around the world for millions of years during the post-extinction recovery period.
"Therapsid fossils like Lystrosaurus are important because they teach us about the resilience of our own extinct relatives in the face of extinction, and provide clues to which traits conferred success on lineages during this turbulent time," said Adam Huttenlocker, one of the paper's authors. "Lystrosaurus was particularly prolific, making it possible to build a large dataset and to sacrifice some specimens for histology to study the growth patterns recorded in its bones."
So what did they find? Before the extinction event, the creature was about the size of a pygmy hippo. After the event, though, it was the size of a large dog. This is, in part, due to its altered lifespan. While it lived 13 to 14 years before the event, it then lived to be 2 to 3 years old afterward.
This means that it's likely the animal started breeding when it was a lot younger. However, this breeding behavior is not isolated to ancient animals. The Atlantic cod has undergone a similar effect due to overfishing; the fish are now breeding younger and becoming smaller.
"Although it's hard to see the effects in our daily lives, there is substantial evidence that we are the middle of a sixth mass extinction right now," Huttenlocker said. "It has been predicted that half of mammal species could become extinct by the end of the next century if present patterns continue; that's more than 1,000 times greater than previous estimates of natural extinctions, a trend not seen since the End-Permian or End-Cretaceous extinctions."
The findings reveal a bit more about how animals respond to extinction, and show they're more likely to survive if they reproduce early and decrease in size.
The findings were published in the April edition of the journal Scientific Reports.
