The Giant Beaver (Castoroides ohioensis) was a huge species of rodent, with a length up to 2.5 m (8.2 feet) and an estimated weight of 220 kg (485 lbs). It lived in North America during the Pleistocene epoch, and went extinct during the last Ice Age, 10,000 years ago. The arrival of humans in the Americas is thought to be a factor in its extinction. It was one of the abundant Pleistocene megafauna - a wide variety of very large mammals that lived during the Pleistocene. One of the big differences between the Giant Beaver and modern beaver species other than size is their teeth. Modern beavers have chisel-like teeth for gnawing on wood. The teeth of the Giant Beaver are bigger and broader, and grew to about 15 centimeters (6 inches) long. In addition, the tail of the Giant Beaver must have been narrower, and its hind legs shorter. Its great bulk might have restricted its movement on land (although large squat-legged hippopotamuses can move well on land with little difficulty). The first Giant Beaver fossils were discovered in 1837 in a peat bog in Ohio, hence its species epithet ohioensis. Nothing is known on whether or not the Giant Beaver built lodges like modern beavers. In Ohio, there have been claims of a possible Giant Beaver lodge four feet high and eight feet in diameter, formed from small saplings.