Rodents of unusual size are found in Oregon’s fossil record

Modern and prehistoric beaver skulls

The Museum of Natural and Cultural History kicks off a monthlong celebration of Charles Darwin’s birth month by unveiling new fossils sure to make Oregon State University fans jealous.

The fossils of the giant beaver, of the genus Castoroides, are found across much of eastern North America, but fossils recently discovered in the Yamhill River reveal that Oregon, too, had its own rodent of unusual size about 20,000 years ago.

“Although another giant beaver fossil was rumored to have been found in Oregon, these are the first Castoroides fossils found west of the Rockies with definitive, well-recorded locality information,” said paleontologist Samantha Hopkins.

Scientists estimate that giant beavers were 5 to 6 feet long and weighed about 120 to 220 pounds. They went extinct at the end of the Pleistocene epoch, about 12,000 years ago.

Despite their name, giant beavers are not very closely related to beavers seen today.

A big clue comes from their teeth. While modern beavers have sharp, flat front teeth for cutting through wood, the front teeth of giant beavers are more rounded and covered in ridges.

“This tells us that giant beavers probably weren’t doing the same kind of wood cutting, weren’t building dams and lodges like beavers today,” Hopkins said.

The new giant beaver fossils will be on display at the museum beginning Wednesday, Feb. 2. Also on Feb. 2, Hopkins delves into the story of giant beavers for the museum’s Ideas on Tap program at 6 p.m. The free talk will be held virtually on Zoom and Facebook.

The fossil fun continues all February long as the museum celebrates Charles Darwin's 213th birthday with additional natural history programming.

On Thursdays, Feb. 3 and 17, drop in any time between  and 7 p.m. to meet museum paleontologists and see fossils from the museum's vaults. Fossil Finds from the Vault is included with regular admission and free for UO ID card holders.

As always, the Museum of Natural and Cultural History is open until 8 p.m. on Thursdays, so stay late and explore Oregon’s natural history.

From Wednesday, Feb. 9, through Sunday, Feb. 13, Charles Darwin's birthday meets Valentine's Day during the museum store's annual Love Science sale. From barware and jewelry to books and toys, there are science-themed gifts for every valentine on your list. Take 10 percent off all nonconsignment purchases (20 percent off for museum members and UO faculty and staff) and receive a free tote bag with a purchase of $50 or more. Admission to the museum store is always free.

— By Lauren Willis, Museum of Natural and Cultural History