Scots scientists help discover primeval beaver

Fossils discovered by scientists in New Mexico belong to a previously identified type of small, furry mammal resembling modern-day rodents that were scrappy enough to thrive after the dinosaurs died out.

“It’s interesting that this odd, now extinct group, was among the few to survive the mass extinction and thrive in the aftermath”, said Thomas Williamson of the New Mexico Museum of Natural History and Science, who led research that appeared Monday in the Zoological Journal of the Linnean Society.

“It’s larger than nearly all of the mammals that lived with the dinosaurs, and also had a plant-eating diet, which few if any dinosaur-living mammals had”.

They survived the events that led to the extinction of dinosaurs, and spread through what is now Asia and North America.

“[During the Jurassic] these animals were all pretty small”, said Stephen Brusatte, one of the researchers, in an interview with BBC News.

The newly discovered species is called Kimbetopsalis simmonsae.

Even though it was not categorized as a rodent (like beavers), the fossils uncovered that it presented with buck-toothed incisors at the front of its snouts, which rings familiar.

The researchers noted that they believe Kimbetopsalis could have suffered from competition with rodents, which emerged 57 million years ago.

But when nonavian dinosaurs went extinct, mammals continued to diversify and take over niche environments that dinosaurs once filled. As new theories uncovered, the extinction of the animals was caused by an asteroid impact in New Mexico that aggravated volcanic eruptions in India. “Then the asteroid hit, wiped out the dinosaurs and suddenly – in geological terms – this [group of animals] started to proliferate and get bigger”, said Brusatte. Kimbetopsalis was among the few to survive the catastrophic events that ultimately changed the course of history and made the world into what it is today.

The dinosaurs ruled the Earth for over 100 million years, but it all turned into chaos within one moment. “And they did this quickly, very quickly”. Kimbetopsalis simmonsae lived only about 500 thousand years after the dinosaur extinction. “It ate plants and was the size of a beaver”, Dr. Brusatte added.

After comparing the new fossils with others from around the world, Williamson, Secord and colleagues at the University of Edinburgh concluded Raymond had found a new species, which they named Kimbetopsalis simmonsae, after the wash where it was found and a scientist who has studied the mammals.