Fossil Giant Beaver (Castoroides) - Florida

This is a rare, partial tooth (incisor) of one of the largest rodents to ever live, the giant beaver Castoroides leiseyorum. It has well defined striations and nice, black enamel preservation. These teeth are difficult to find and are rarely offered for sale.

Castoroides leiseyorum, an extinct genus of giant beaver reach 6-8 feet in length and weighed as much as 500 lbs, about the size of a good size black bear. It would have looked similar to modern beavers and lived during the Pleistocene, first appearing 1.5 million years ago and going extinct about 11,000 years ago. It would NOT have been closely related to modern beavers.

One of the defining characteristics of the giant beaver were their incisors, which differ in size and shape than those of modern beavers. Modern beavers have chisel-like incisor teeth for gnawing on wood, while the teeth of the giant beaver were bigger and broader, and grew to about 6 inches long. These incisors would not have been as efficient at cutting wood, therefore it is possible that the giant beaver did not construct dams.

There are two species of giant beavers found in North America. Castoroides leiseyorum found only in Florida and Castoroides ohioensis or Castoroides nebrascensis found throughout the US and Canada.