Researchers Find New Species Of Ancient Beaver In Oregon
The fossil of a new beaver species that lived 28 million years ago has recently been discovered in eastern Oregon, according to a new study.
The beaver is among one of 20 other rodent species recently described, and remarkably it could be related to the modern beaver, writes Nature World News. The study was published in the journal Annals of Carnegie Museum.
The fossilized beaver skull and teeth were unearthed close to the visitor center at the John Day Fossil Beds National Monument, according to the monument's paleontologist, Joshua Samuels. However, unlike other species of ancient beavers found at this site, the new specimen, named Microtheriomys brevirhinus, appears related to the modern beaver.
The new find is less than half the size of a modern beaver and related to beavers from Asia that crossed the Bering land bridge to North America about 7 million years ago, ABC News reports.
Researchers analyzed radioactive isotopes from layers of volcanic ash left behind in the ground to determine the approximate age of the beaver.
"We've got badlands exposures here," paleontologist Samantha Hopkins, from the University of Oregon, told ABC News. "As they get wet, whenever it rains or snows and the temperature heats or cools, the claystone these things are in shrinks and swells. The bones are pushed out. The rock breaks apart. The fossils are exposed. This one just came out of the ground it was preserved in."
The beaver was alive during the Oligocene period, about 30 million years after the dinosaurs.
"While there is relatively little castorid (beaver species) diversity today," Samuels noted, "there are hundreds of species (many of which are really important members of their faunal communities) in the fossil record of the Northern Hemisphere, and a better understanding of their diversity and evolutionary relationships has a lot to tell us about processes driving mammalian evolution over the last 40 million years."