Castoroides

Castoroides ohioensis · The giant beaver, Castoroides ohioensis, was an extinct, bear-sized beaver that lived across most of North America during the Pleistocene.

Also called Giant beaver.

It lived about 1.9 to 0.011 million years ago.

Castoroides
Photo: Olmagon, CC BY-SA 4.0
Castoroides
Photo: Daderot, Public domain
Castoroides
Photo: Ghedoghedo, CC BY-SA 3.0

Taxonomy

KingdomAnimalia
PhylumChordata
ClassMammalia
OrderRodentia
FamilyCastoridae
GenusCastoroides
SpeciesCastoroides ohioensis

Where its fossils were found

North America, from Alaska and Canada to Florida, mostly around the Great Lakes.

Fun facts

  • Giant beavers could grow as long as 2.2 meters (7.2 feet), making them the largest known beavers ever.
  • Giant beaver teeth were up to 15 cm (6 in) long, and their enamel was ridged and textured rather than smooth like a modern beaver's.
  • Unlike living beavers, giant beavers probably ate mostly underwater plants instead of wood, and there's no evidence they built dams or lodges.
  • The giant beaver's skull suggests it could take more oxygen into its lungs, which would have helped it spend long periods underwater.

Play it

The Castoroides was the creature in the Prehistoric daily on October 15, 2026. Can you identify tomorrow's from its photos? Every day brings a new creature to place from kingdom to genus, map and name.

Play today's creature or replay a past daily

Facts and taxonomy adapted from Wikipedia (CC BY-SA 4.0).