Animal Diversity Web

A sin­gle mod­ern species is found in the fam­ily An­tilo­capri­dae, but the group has a fos­sil record going back to the Miocene. Dur­ing its his­tory, the An­tilo­capri­dae has in­cluded a di­verse array of species (es­pe­cially dur­ing the Pliocene and Pleis­tocene), some of which had mul­ti­ple and bizarre horns.

The mod­ern prong­horn is found in the deserts and dry grass­lands of west­ern North Amer­ica. Prong­horns are of medium size, with a head and body be­tween 1 and 1.5 m in length and a weight up to around 60 kg. Their body is stocky and they have long, thin legs. Their coat is pale brown dor­sally and whitish ven­trally, and they have dis­tinc­tive black and white mark­ings on their heads and necks. The pelage is dense and ex­cel­lent in­su­la­tion against both heat and cold. Their most dis­tinc­tive fea­ture is their horns, which are like those of bovids in that they con­sist of a ker­ati­nous sheath over a bony core, but dif­fer be­cause the ker­ati­nous sheath is shed pe­ri­od­i­cally (an­nu­ally in males, ir­reg­u­larly in fe­males). These horns are erect and con­sist of two branches or prongs, a short branch ex­tend­ing for­ward and lo­cated around halfway up the horn, and a longer, back­wardly di­rected tip.

The skulls of prong­horns are also dis­tinc­tive. They lack a sagit­tal crest. A com­plete pos­tor­bital bar is pre­sent, and the or­bits are large and placed far back on the skull, be­hind the level of the last molar. A vacu­ity (space) sep­a­rates the nasal from the lacrimal on each side of the ros­trum. The lacrimal canal is in­side the orbit and has a sin­gle open­ing.

The post­cra­nial skele­ton of prong­horns is that of a long-dis­tance run­ner. The legs are long and parax­onic; the 3rd and 4th metapo­di­als are fused to form can­non bones, the lat­eral dig­its are lost (the lat­eral metapo­di­als may be pre­sent as ves­tiges), and the tarsals are re­duced in num­ber and gen­er­ally cuboidal in shape. Prong­horn are among the fastest long-dis­tance run­ners, achiev­ing bursts of speed of about 95 km/hr, and able to main­tain speeds in ex­cess of 50 km/hr for dis­tances of sev­eral kilo­me­ters.

Prong­horn have hyp­sodont, se­len­odont cheek teeth. As in deer and bovids, the upper in­cisors are re­placed by a horny pad, and the lower ca­nine is in­cisor-like. The den­tal for­mula is 0/3, 0/1, 3/3, 3/3 = 32.

These ar­tio­dactyls are usu­ally found in small herds or bands dur­ing the sum­mer, but in larger ag­gre­ga­tions of up to around 100 in­di­vid­u­als in the win­ter. Their herds have a well-de­vel­oped so­cial hi­er­ar­chy. The breed­ing sys­tem dur­ing the sum­mer is poly­gy­onous.

Prong­horns have ex­cel­lent vi­sion, and it has been sug­gested that the po­si­tion of their eyes, high up on their skulls, is an adap­ta­tion that al­lows them to main­tain vig­i­lance for preda­tors while they con­tinue to crop veg­e­ta­tion on the ground.

Tech­ni­cal char­ac­ters

Ref­er­ences and lit­er­a­ture cited:

Feld­hamer, G. A., L. C. Drick­amer, S. H. Vessey, and J. F. Mer­ritt. 1999. Mam­mal­ogy. Adap­ta­tion, Di­ver­sity, and Ecol­ogy. WCB Mc­Graw-Hill, Boston. xii+563pp.

Nowak, R.M. and J.L. Par­adiso. 1983. Walker's Mam­mals of the World, 4th edi­tion . John Hop­kins Uni­ver­sity Press, Bal­ti­more, MD.

Sav­age, R. J. G. and M. R. Long. 1986. Mam­mal Evo­lu­tion: An Il­lus­trated Guide. Facts on File Pub­li­ca­tions, UK. 251 pp.

Simp­son, C. D. 1984. Ar­tio­dactyls. Pp. 563-587 in An­der­son, S. and J. K. Jones, Jr. (eds). Or­ders and Fam­i­lies of Re­cent Mam­mals of the World. John Wiley and Sons, N.Y. xii+686 pp.

Vaughan, T. A. 1986. Mam­mal­ogy. Third Edi­tion. Saun­ders Col­lege Pub­lish­ing, N.Y. vii+576 pp.

Vaughan, T. A., J. M. Ryan, N. J. Czaplewski. 2000. Mam­mal­ogy. Fourth Edi­tion. Saun­ders Col­lege Pub­lish­ing, Philadel­phia. vii+565pp.

Wil­son, D. E., and D. M. Reeder. 1993. Mam­mal Species of the World, A Tax­o­nomic and Ge­o­graphic Ref­er­ence. 2nd edi­tion. Smith­son­ian In­sti­tu­tion Press, Wash­ing­ton. xviii+1206 pp.

Con­trib­u­tors

Phil Myers (au­thor), Mu­seum of Zo­ol­ogy, Uni­ver­sity of Michi­gan-Ann Arbor.