Rodentia
One of the most successful mammalian orders
Rodents are mammals characterized primarily by a single pair of continuously growing incisors in both the upper and lower jaws. These incisors are large and chisel-shaped, well adapted for gnawing through tough materials. Rodents lack canine teeth and typically have a distinct gap called a diastema between their incisors and their cheek teeth. Rodents include all of today's mice, rats, gerbils, guinea pigs and porcupines, but during the Pleistocene epoch some North American rodents reached massive sizes. In particular the Giant Beaver Castoroides may have been the largest rodent to live in North America.
Giant beaver
Castoroides ohioensis
Temporal Range: 1.9 million years ago to approximately 11,000 years ago
Geographic Range: Found across North America from the Yukon to Florida
Species: C. ohioensis, C. dilophidus
Diet: Herbivorous, grasses, aquatic plants
Castoroides, commonly known as the giant beaver, was one of the largest rodents ever to live in North America. This massive mammal inhabited lakes, marshes, and wetlands during the Fossils have been discovered across much of North America, with one species most often found in the Midwest and another found in the southeastern US, indicating that it was widespread and well adapted to aquatic environments.
Unlike modern beavers, Castoroides was enormous, reaching lengths of about 7 feet and weighing about as much as a small bear. Its body was robust, with large hind feet that likely aided swimming. The tail may have been longer and less paddle-shaped than that of living beavers.
One of its most notable features was its huge incisors, which could grow to be over 6 inches long. These teeth had a textured enamel surface and differed from the chisel-like incisors of modern beavers. Evidence suggests that Castoroides fed primarily on aquatic vegetation rather than cutting large trees.
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