Antilocapridae

The Antilocapridae are a family of artiodactyls endemic to North America. Their closest extant relatives are the giraffids[1] with which they comprise the superfamily Giraffoidea. 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.

Antilocapridae
Temporal range: Early Miocene–recent
Pronghorn antelope.jpg
Pronghorns in Fort Keogh, Montana
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Superfamily: Giraffoidea
Family: Antilocapridae
J. E. Gray, 1866
Subfossil genera

Antilocapra
Capromeryx
Stockoceros
Tetrameryx
For fossil genera, see text.

DescriptionEdit

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.

ClassificationEdit

The antilocaprids are ruminants of the clade Pecora. Other extant pecorans are the families Giraffidae (giraffes), Cervidae (deer), Moschidae (musk deer), and Bovidae (cattle, goats and sheep, wildebeests and allies, and antelopes). The exact interrelationships among the pecorans have been debated, mainly focusing on the placement of Giraffidae, but a recent large-scale ruminant genome sequencing study suggests Antilocapridae are the sister taxon to Giraffidae, as shown in the cladogram below.[2]

Ruminantia
Tragulina

Tragulidae  

Pecora

Antilocapridae  

Giraffidae  

Cervidae  

Bovidae  

Moschidae  

EvolutionEdit

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 subtropical woodlands into open savannah grasslands.[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]

SpeciesEdit

ReferencesEdit

  1. ^ "Pronghorn (Antilocapra americana) Fact Sheet: Taxonomy & History". International Environment Library Consortium. Retrieved 8 August 2020.
  2. ^ a b c Chen, L.; Qiu, Q.; Jiang, Y.; Wang, K. (2019). "Large-scale ruminant genome sequencing provides insights into their evolution and distinct traits". Science. 364 (6446): eaav6202. Bibcode:2019Sci...364.6202C. doi:10.1126/science.aav6202. PMID 31221828.
  3. ^ Savage, RJG; Long, MR (1986). Mammal Evolution: an illustrated guide. New York: Facts on File. pp. 232–233. ISBN 0-8160-1194-X.
  4. ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 280. ISBN 1-84028-152-9.
  5. ^ Richards, G.D.; McCrossin, M.L. (1991). "A new species of Antilocapra from the late Quaternary of California". Geobios. 24 (5): 623–635. doi:10.1016/0016-6995(91)80027-W.
  6. ^ a b Davis, E.B.; Calède, J.J. (January 2012). "Extending the utility of artiodactyl postcrania for species-level identifications using multivariate morphometric analyses". Palaeontologia Electronica. 15 (1): 1A:22p. Retrieved 13 August 2020.
  7. ^ a b c Semprebon, 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. doi:10.1016/j.palaeo.2007.06.006.
  8. ^ Carranza-Castenada, O.; Aranda-Gomez, J.J.; et al. (April 2013). "The Early-Late Hemphillian (HH2) faunal assemblage from Juchipila Basin, State of Zacatecas, Mexico, and its biochronologic correlation with other Hemphillian faunas in central Mexico" (PDF). Contributions in Science. 521: 13–49. S2CID 53606726. Archived from the original (PDF) on 2019-02-27. Retrieved 13 August 2020.
  9. ^ 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.
  10. ^ Prothero, Donald R. (2007). The Evolution of Artiodactyls. Johns Hopkins University Press. p. 232. ISBN 9780801887352.
  11. ^ Beatty, B.L.; Martin, L.D. (June 2009). "The earliest North American record of the Antilocapridae (Artiodactyla, Mammalia)". PalaeoBios. 29 (1): 29–35. Retrieved 13 August 2020.