Giant Beaver
Castoroides ohioensis Foster
Description: The giant beaver, Castoroides ohioensis, is represented by its large teeth. To date there have been only a
few documented occurrences in New Jersey and all are cheek molars. The surface enamel is plicated or ruffled down the
length of the tooth, which is slightly curved, looking similar to a curved horse tooth. The top of the tooth has a ridge that
meanders back and forth to create the grinding surface. The teeth are usually 15 mm (about .5 in) by 17 mm (about .6 in) on
the top and 5 cm (about 2 in) long. Modern day beaver teeth are sometimes recovered and may resemble Castoroides teeth
but can be distinguished by size. Castoroides teeth are almost three times as big.

Other skeletal material undoubtedly exists, but to date, there has been none found or at least recognized.

Commonality: Any giant beaver material is rare.

Similar fossils: The teeth (molars) slightly resemble horse teeth but these lack the curve of the giant beaver teeth.

Size: The teeth of the giant beaver suggest it was a large rodent about the size of a modem black bear, about 2 meters
(about 6 feet) long.

Notes: The presence of the giant beaver is inconsistent with the usual Ice Age fauna and probably existed during the
interglacial periods when the temperature was much like it is today. A tooth that was found at Big Brook is presently on
display in the New Jersey State Museum in Trenton.
a. Cheek Molar  b. Incisor
Castoroides ohioensis Foster
Painting by Don Miller  at
Tooth - Molar
from the State Museum, Trenton