Buzz
Oregon was once inhabited by beaver-like rodents no larger than squirrels. A recent study of ancient creatures discovered in the John Day Formation, a significant fossil site in Oregon, revealed a new species of these miniature rodents that thrived 28 million years ago. The research findings are detailed in the Annals of Carnegie Museum.
Named Microtheriomys brevirhinus, this newly identified species stands out because, despite its small size compared to modern beavers, it shares a closer evolutionary link with them than with other beavers from its era. While many ancient beavers dug burrows, evidence from the skull and teeth of M. brevirhinus suggests it was adapted for swimming and dam-building.
The John Day fossil beds, now designated as a national monument, were created by layers of volcanic ash that covered central Oregon. This area boasts one of the most extensive and well-preserved collections of animal and plant fossils in North America, with remnants dating back 40 million years embedded in its rock layers.
A scenic view from a trail in John Day Fossil Beds National Monument. Image Credit: Finetooth via Wikimedia Commons // CC BY-SA 3.0
During the Oligocene epoch, M. brevirhinus roamed this area. They were not the sole beaver species present at the time. “Although modern beaver diversity is limited, the fossil record of the Northern Hemisphere reveals hundreds of species, many of which played crucial roles in their ecosystems,” explained University of Oregon paleontologist Samantha Hopkins in an interview with the AP. Studying these ancient beavers provides valuable insights into the evolutionary journey of mammals.
