The Antilocapridae are a
family of ruminant
artiodactyls endemic to
North America. Their closest
extant relatives are the
giraffids.[1] Only one species, the
pronghorn (Antilocapra americana), is living today; all other members of the family are
extinct. The living pronghorn is a small
ruminant mammal resembling an
antelope.
Description
In most respects, antilocaprids resemble other
ruminants. They have a complex, four-chambered stomach for digesting tough plant matter,
cloven hooves, and small, forked horns. Their horns resemble those of the
bovids, in that they have a true horny sheath, but, uniquely, they are shed outside the breeding season, and subsequently regrown. Their lateral toes are even further diminished than in bovids, with the digits themselves being entirely lost, and only the
cannon bones remaining. Antilocaprids have the same
dental formula as most other ruminants: 0.0.3.33.1.3.3.
The ancestors of pronghorn diverged from the giraffids in the
Early Miocene.[2] This was in part of a relatively late mammal diversification following a climate change that transformed
subtropicalwoodlands into open
savannahgrasslands.[2]
The antilocaprids evolved in North America, where they filled a niche similar to that of the bovids that evolved in the Old World. During the
Miocene and
Pliocene, they were a diverse and successful group, with many different species. Some had horns with bizarre shapes, or had four, or even six, horns. Examples include Osbornoceros, with smooth, slightly curved horns, Paracosoryx, with flattened horns that widened to forked tips, Ramoceros, with fan-shaped horns, and Hayoceros, with four horns.[3][4]
^Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 280.
ISBN1-84028-152-9.
^
abcSemprebon, G.M.; Rivals, F. (September 2007). "Was grass more prevalent in the pronghorn past? An assessment of the dietary adaptations of Miocene to Recent Antilocapridae (Mammalia: Artiodactyla)". Palaeogeography, Palaeoclimatology, Palaeoecology. 253 (3–4): 332–347.
Bibcode:
2007PPP...253..332S.
doi:
10.1016/j.palaeo.2007.06.006.
^Janis, Kathleen M. (1998). Evolution of Tertiary Mammals of North America: Volume 1, Terrestrial Carnivores, Ungulates, and Ungulate Like Mammals. Cambridge University Press. p. 496.
^Prothero, Donald R. (2007). The Evolution of Artiodactyls. Johns Hopkins University Press. p. 232.
ISBN9780801887352.