The Antilocapridae are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of ruminant artiodactyls endemic to

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

. Their closest

extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

relatives are the giraffids. Only one species, the pronghorn (''Antilocapra americana''), is living today; all other members of the family are

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

. The living pronghorn is a small

ruminant Ruminants are herbivorous grazing or browsing artiodactyls belonging to the suborder Ruminantia that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microb ...

mammal resembling an

antelope The term antelope refers to numerous extant or recently extinct species of the ruminant artiodactyl family Bovidae that are indigenous to most of Africa, India, the Middle East, Central Asia, and a small area of Eastern Europe. Antelopes do ...

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: .

Classification

The antilocaprids are

s of the clade

Pecora Pecora is an Order (biology), infraorder of Artiodactyla, even-toed hoofed mammals with ruminant digestion. Most members of Pecora have cranial appendages projecting from their frontal bones; only two extant genera lack them, ''Hydropotes'' and ...

. Other extant pecorans are the families

Giraffidae The Giraffidae are a family (biology), family of ruminant artiodactyl mammals that share a recent common ancestor with deer and bovids. This family, once a diverse group spread throughout Eurasia and Africa, presently comprises only two extant ge ...

(

giraffe The giraffe is a large Fauna of Africa, African even-toed ungulate, hoofed mammal belonging to the genus ''Giraffa.'' It is the Largest mammals#Even-toed Ungulates (Artiodactyla), tallest living terrestrial animal and the largest ruminant on ...

s), Cervidae (deer), Moschidae (

musk deer Musk deer can refer to any one, or all eight, of the species that make up ''Moschus'', the only extant genus of the family (biology), family Moschidae. Despite being commonly called deer, they are not true deer belonging to the family Cervidae, b ...

), and

Bovidae The Bovidae comprise the family (biology), biological family of cloven-hoofed, ruminant mammals that includes Bos, cattle, bison, Bubalina, buffalo, antelopes (including Caprinae, goat-antelopes), Ovis, sheep and Capra (genus), goats. A member o ...

(

cattle Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are calle ...

, goats and sheep, wildebeests and allies, and

s). The exact interrelationships among the pecorans have been debated, mainly focusing on the placement of Giraffidae, but a large-scale ruminant genome sequencing study in 2019 suggested that Antilocapridae are the sister taxon to Giraffidae, as shown in the

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below.

Evolution

The ancestors of pronghorn diverged from the giraffids in the

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

. This was in part of a relatively late mammal diversification following a climate change that transformed

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...

woodland A woodland () is, in the broad sense, land covered with woody plants (trees and shrubs), or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunli ...

s into open

savannah A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach th ...

grassland A grassland is an area where the vegetation is dominance (ecology), dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes such as clover, and other Herbaceo ...

s. 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 The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

and

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Osbornoceros'', with smooth, slightly curved horns, ''Paracosoryx'', with flattened horns that widened to forked tips, '' Ramoceros'', with fan-shaped horns, and '' Hayoceros'', with four horns.

Species

Subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Antilocaprinae **

Tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...

Antilocaprini ***

Genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

'' Antilocapra'' ****'' Antilocapra americana'' - pronghorn *****''A. a. americana'' - Common pronghorn *****''A. a. mexicana'' - Mexican pronghorn *****''A. a. peninsularis'' - Baja California pronghorn *****''A. a. sonoriensis'' - Sonoran pronghorn *****''A. a. oregona'' - Oregon pronghorn ****†'' Antilocapra pacifica'' ***Genus †'' Texoceros'' ****''Texoceros altidens'' ****''Texoceros edensis'' ****''Texoceros guymonensis'' ****''Texoceros minorei'' ****''Texoceros texanus'' ****''Texoceros vaughani'' **Tribe †Ilingoceratini ***Genus †'' Ilingoceros'' ****''Ilingoceros alexandrae'' ****''Ilingoceros schizoceros'' ***Genus †'' Ottoceros'' ****''Ottoceros peacevalleyensis'' ***Genus †'' Plioceros'' ****''Plioceros blicki'' ****''Plioceros dehlini'' ****''Plioceros floblairi'' ***Genus †'' Sphenophalos'' ****''Sphenophalos garciae'' ****''Sphenophalos middleswarti'' ****''Sphenophalos nevadanus'' **Tribe †Proantilocaprini ***Genus †'' Proantilocapra'' ****''Proantilocapra platycornea'' ***Genus †'' Osbornoceros'' ****''Osbornoceros osborni'' **Tribe Stockoceratini ***Genus †'' Capromeryx'' - (junior synonym ''Breameryx'') ****''Capromeryx arizonensis'' - (junior synonym ''B. arizonensis'') ****''Capromeryx furcifer'' - (junior synonyms ''B. minimus'', ''C. minimus) ****''Capromeryx gidleyi'' - (junior synonym ''B. gidleyi'') ****''Capromeryx mexicana'' - (junior synonym ''B. mexicana'') ****''Capromeryx minor'' - (junior synonym ''B. minor'') ****''Capromeryx tauntonensis'' ***Genus †'' Ceratomeryx'' ****''Ceratomeryx prenticei'' ***Genus †'' Hayoceros'' ****''Hayoceros barbouri'' ****''Hayoceros falkenbachi'' ***Genus †'' Hexameryx'' ****''Hexameryx simpsoni'' ***Genus †'' Hexobelomeryx'' ****''Hexobelomeryx fricki'' ****''Hexobelomeryx simpsoni'' ***Genus †'' Stockoceros'' ****''Stockoceros conklingi'' (junior synonym ''S. onusrosagris'') Antilocaprid

***Genus †'' Tetrameryx'' ****''Tetrameryx irvingtonensis'' ****''Tetrameryx knoxensis'' ****''Tetrameryx mooseri'' ****''Tetrameryx shuleri'' ****''Tetrameryx tacubayensis'' *Subfamily † Merycodontinae **Genus †'' Cosoryx'' ***''Cosoryx cerroensis'' ***''Cosoryx furcatus'' ***''Cosoryx ilfonensis'' **Genus †'' Merriamoceros'' ***''Merriamoceros coronatus'' **Genus †'' Merycodus'' (syn. ''Meryceros'' and ''Submeryceros'') ***''Merycodus crucensis'' ***''Merycodus hookwayi'' ***''Merycodus joraki'' ***''Merycodus major'' ***''Merycodus minimus'' ***''Merycodus minor'' ***''Merycodus necatus'' ***''Merycodus nenzelensis'' ***''Merycodus prodromus'' ***''Merycodus sabulonis'' ***''Merycodus warreni'' **Genus †'' Paracosoryx'' ***''Paracosoryx alticornis'' ***''Paracosoryx burgensis'' ***''Paracosoryx dawesensis'' ***''Paracosoryx furlongi'' ***''Paracosoryx loxoceros'' ***''Paracosoryx nevadensis'' ***''Paracosoryx wilsoni'' **Genus †'' Ramoceros'' ***''Ramoceros brevicornis'' ***''Ramoceros marthae'' ***''Ramoceros merriami'' ***''Ramoceros osborni'' ***''Ramoceros palmatus'' ***''Ramoceros ramosus''

References

{{Authority control Mammal families Extant Miocene first appearances Taxa named by John Edward Gray *