Jonathan J. M. Calede and a team of scientists found the ancient beaver fossil in Montana, and knew right away it belonged to a beaver because of its teeth, according to Ohio State News. They named the new species Microtheriomys articulaquaticus, according to the Royal Society Open Science. The age of the fossil means this beaver was active during the Oligocene Epoch, which lasted from between 33.9 to 23 million years ago, according to the University of California, Berkeley. This was the epoch in which some of today's most beloved mammals, like tusked elephants and early horses, appeared. And now, it turns out, beavers.
Microtheriomys articulaquaticus was different from today's beavers in many ways. In fact, it lacked two of the current beaver's most defining attributes, according to Ohio State News. It didn't have a flat tail, and it probably didn't eat wood, preferring plants instead. Further, it was much smaller, weighing less than two pounds instead of around 50. This isn't unexpected, however. There's actually a scientific concept known as Cope's Rule, according to which animals become larger over time as they branch up an evolutionary tree. Calede looked at beaver evolution and found that this held true.
Around 12,000 years ago there was a giant beaver in North America the size of a black bear. This now-extinct behemoth, scientific name Castoroides ohioensis, could grow to be as tall as 7.2 feet and as heavy as 275 pounds, according to the Illinois State Museum.
ncG1vNJzZmivp6x7qL7Up56eZpOkunB9j3Btbm5nZLWww4ytn6KrXZu8tL%2FIpWSmmalitaLCxGaaoZmenLKledOhnGavka56uLGMrZ%2BipptirqO71K1km52Rq7Kzv44%3D