Name:

Castoroides (Greek for "of the beaver family"); pronounced CASS-tore-OY-dees

Habitat:

Marshlands of North America

Historical Epoch:

Pleistocene-Ice Age (5 million-10,000 years ago)

Size and Weight:

About 8 feet long and 200 pounds

Diet:

Omnivorous

Distinguishing Characteristics:

Large size; enormous front teeth

About Castoroides:

It seems that every contemporary mammal has a giant ancestor lurking in the mists of prehistory.

Exhibit A is Castoroides, better known as the Giant Beaver, a huge rodent with six-inch-long teeth that managed to survive until the end of the last Ice Age. We have no idea what kinds of dams Castoroides built (that is, if it built any dams at all), or whether it was hunted to extinction by early humans. As befitting its epic size, Castoroides has been honored as the state fossil of Minnesota.