Mammalia, Order Rodentia, Family Castoridae
Time: Holocene to Pleistocene
120 mm long, 105 mm high, 85 mm across (as opened)
Bonner Springs, Kansas
This skull comes from a Beaver known as Castor canadensis. This is
the same species as is extant today. Beavers derive the genus name
from the castor glands under the tail that they use to mark their
territory. Note the large teeth with which the beaver fells trees
for food and building material. They grow continuously throughout
the beaver’s life to always provide a sharp cutting surface.
It comes from a series of river terrace deposits near Bonner Springs,
Kansas. These specimens are found as drifts on the river banks and
sand bars, and as such have possibly been reworked from older deposits.
They are found in association with bison, mammoths, mastodons, muskoxen,
deer, peccary, short-faced bears, and others. Most of them have been
dated as Rancholabrean Stage in age, and are so about 10,000 years
old. Specimens of bison have ranged from 8,000 to 35,000 years in
age which provides a viable estimate of the age.