Pronghorn horn cores

Pronghorn horn cores

P-57606

Pronghorn

Pronghorn, cloven-hooved ungulate

Española area, Rio Arriba County

Middle Miocene, 14 million years ago

Pair of complete horn cores

Pronghorns (family Antilocapridae) are an advanced group of ruminant artiodactyls (even-toed or cloven-hoofed ungulates that chew their cud) that are restricted to North America throughout their history, from the middle Miocene (16 milllion years ago) to the present. Meryceros and the closely related Merycodus, both known from the middle Miocene of New Mexico, are among the earliest known antilocaprids, characterized by simple forked horns in the shape of a “Y”. The horn cores are composed of bone, which is covered by a horn sheath of keratinous material in the living animals. The horn sheath is shed and replaced every year but the bony horn cores are permanently attached to the skull. This contrasts with most deer (family Cervidae) in which the males have bony antlers that are shed and then regrown every year and cow, sheep, antelope, etc. (family Bovidae) in which both the bony horn core and keratinous horn sheath are permanent.