Survival of the Newest: the Mammals that Survive Mass Extinctions Aren't as 'Boring' as Scientists Thought
Published:16 Nov.2023    Source:Field Museum

When an asteroid hit the Earth 66 million years ago, it set off a devastating mass extinction. The dinosaurs (except for a few birds) all died out, along with lots of the mammals. But some small mammals survived, laying the groundwork for all the mammals alive today. For decades, scientists have assumed that mammals and their relatives that survived challenging times (like those during mass extinctions) made it because they were generalists that were able to eat just about anything and adapt to whatever life threw at them.

The idea of the 'survival of the unspecialized' goes back to the 1800s, and the conventional wisdom is that generalized animals are the least likely to go extinct. But we found that the ones that survived more often only seemed generalized in hindsight, when compared with their later descendents. They were actually pretty advanced animals for their time, with new traits that might have helped them survive and provided evolutionary flexibility
A new study into the mammal family tree through multiple mass extinctions revealed that the species that survived aren't as generic as scientists had thought: instead, having new and different traits can be the key to succeeding in the aftermath of a catastrophe. Animals with novel traits like new tooth features, or jaws that work a little better at breaking down different food items, don't really take over ecologically until the incumbent, older lineages go extinct.