Fossil Friday – bison horn

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Bison are among the most common animals in the Diamond Valley Lake Local Fauna. While no complete bison skeletons were recovered during excavations for the construction of the reservoir, large numbers of fragments, individual bones and teeth, and associated bones were discovered. Some of these are impressively large, including the horn core shown here.

Bison are members of the Family Bovidae, a diverse group that includes cattle, goats, sheep, and antelope. A characteristic shared by practically all bovids is the presence of horns in males (there are some domestic bovid breeds in which the males lack horns); in many species the females have horns as well. The horns vary greatly in size and shape between species, but they always have certain features in common: they form as outgrowths of the frontal bones on the roof of the skull, they do not branch, and they are covered in a keratin sheath. Keratin doesn’t usually preserve in fossils, so what we generally see in fossils is the rough bone underneath. Because the horn is part of the frontal bone, it is not shed each year like the antlers of deer.

There are two different extinct species of bison known from Diamond Valley, Bison antiquus and Bison latifrons; among other differences, B. latifrons is larger and has much longer horns. As big as this specimen is, it’s not immediately clear which species it represents. It’s on the small side for B. latifrons, but a little larger than some of our B. antiquus specimens.

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