each "horn" of the pronghorn is composed of a slender, laterally flattened blade of bone that grows from the frontal bones of the skull, forming a permanent core. as in the giraffidae, skin covers the bony cores, but in the pronghorn, it develops into a keratinous sheath which is shed and regrown annually. unlike the horns of the family bovidae, the horn sheaths of the pronghorn are branched, each sheath having a forward-pointing tine (hence the name pronghorn). males have a horn sheath about (average ) long with a prong. females have smaller horns that range from (average ) and sometimes barely visible; they are straight and very rarely pronged. males are further differentiated from females in having a small patch of black hair at the angle of the mandible. pronghorns have a distinct, musky odor. males mark territory with a preorbital scent gland which is on the sides of the head. they also have very large eyes with a 320° field of vision. unlike deer, pronghorns possess a gallbladder.