New research reports that, contrary to popular belief, mammals began their massive diversification 10 to 20 million years before the extinction of the dinosaurs.
The study, involving Elis Newham from the University, questioned the familiar story that dinosaurs dominated their prehistoric environment, while tiny mammals took a backseat, until the dinosaurs (besides birds) went extinct 66 million years ago, allowing mammals to shine.
Elis Newham, PhD student in Engineering and the Environment and co-author of the study, which is published Proceedings of the Royal Society B, said:
“The traditional view is that mammals were suppressed during the ‘age of the dinosaurs’ and underwent a rapid diversification immediately following the extinction of the dinosaurs.
“However, our findings were that therian mammals, the ancestors of most modern mammals, were already diversifying considerably before the extinction event and the event also had a considerably negative impact on mammal diversity.”
The old hypothesis hinged upon the fact that many of the early mammal fossils that had been found were from small, insect-eating animals—there didn’t seem to be much in the way of diversity. However, over the years, more and more early mammals have been found, including some hoofed animal predecessors the size of dogs. The animals’ teeth were varied too.
The researchers analysed the molars of hundreds of early mammal specimens in museum fossil collections. They found that the mammals that lived during the years leading up to the dinosaurs’ demise had widely varied tooth shapes, meaning that they had widely varied diets. These different diets proved key to an unexpected finding regarding mammal species going extinct along with the dinosaurs.
You can read the full story on the University website.
The study has appeared online in Forbes, The Guardian and the Daily Mail today.