Happy Ice Age Week: Castoroides better known as the giant beaver, is an extinct genus of beaver that lived throughout North America during the Pleistocene to early holocene some 2.1 million to 11,000 years ago. The first remains of castoroides known to science were consisting of a skull was unearthed from a peat bog near Nashport Ohio in 1837 during the digging of the Ohio Canal. These remains would be formally described by American geologist John Wells Foster in 1838, who named the animal castoroides meaning “beaver like” in latin. Since then hundreds of castoroides specimens have been found from Alaska and Canada on down to Florida, being especially concentrated around the midwestern United States in states near the Great Lakes, particularly Illinois and Indiana. Today two species are considered valid: C. ohioensis & C. dilophidus. Reaching some 6 to 7.5ft (1.8 to 2.3m) in length and 170 to 275lbs (77 to 125kgs) in weight, Casteroides was the largest known rodent in North America during the Pleistocene and the largest known beaver. The hind feet of the giant beaver were much larger than in modern beavers, while the hind legs were shorter. The tail was longer and may not have been paddle-shaped as in modern beavers. The shape of Castoroides large incisors would have made it much less effective at cutting down trees than living beavers, meaning that they likely didn’t build damns and lodges in the same manner. In life castoroides would have been heavily reliant on lakes and wetlands where it would both avoid predators and feed upon primarily aquatic plants. Remains of the giant beaver, along with human artifacts and the remains of other megafauna from several sites shows that there were some interactions between Paleo-Indians and Casteroides. Many native tribes such as the Innu, Mississaugas, Algonquin, & Anishinaabe all feature giant beavers in their traditional mythology, which many believe is evidence of there ancestors interaction with Castoroides.