Sixty-six million years ago the world changed in an instant. A huge asteroid, some 10 kilometers in diameter, smashed into what is now Mexico. It arrived with the force of several million nuclear bombs, and unleashed a deadly cocktail of wildfires, tsunamis, earthquakes, and volcanoes.
It wasn’t a good time to be alive. Scientists estimate that about 75% of all species became extinct, most famously among them the dinosaurs. But some of our furry ancestors managed to make it through the apocalypse. With T. rex and Triceratops now out of the picture, gutsy little mammals had a new world to colonize.
A new fossil from New Mexico is helping us better understand how mammals took advantage of the dinosaur extinction to become the incredibly successful creatures that we know today. It was discovered and studied by a team of researchers that I am part of, led by Thomas Williamson of the New Mexico Museum of Natural History and Science.
Our new mammal, called Kimbetopsalis simmonsae, would have looked like a prehistoric version of a beaver. It was a couple of feet long, weighed 10-40 kilograms, and had buck-toothed incisors at the front of its snout that it used to cut up leaves and branches.
Despite appearances, Kimbetopsalis was no beaver (which is a type of rodent). It was a member of a completely extinct group of mammals called multituberculates, which originated alongside the dinosaurs, survived the extinction, diversified afterwards, and ultimately went extinct 35 million years ago when they were superseded by the smarter, faster-growing modern rodents.