''Agriochoerus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

scansorial Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose num ...

herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

of the

tylopod Tylopoda (meaning "calloused foot") is a suborder of Terrestrial animal, terrestrial herbivorous even-toed ungulates belonging to the biological order, order Artiodactyla. They are found in the wild in their native ranges of South America and Asi ...

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Agriochoeridae, endemic to

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. ''Agriochoerus'' and other agriochoerids possessed claws, which is rare within Artiodactyla, as well as likely being scansorial.Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

Description

sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated s ...

Like other agriochoerids, it possessed a body shape unusual for an artiodactyl. The body was rather elongated and supported by more elongated and slender limbs than those of others within the

Merycoidodontoidea Merycoidodontoidea, sometimes called "oreodonts" or "ruminating hogs", is an extinct superfamily of prehistoric cud-chewing artiodactyls with short faces and fang-like canine teeth. As their name implies, some of the better known forms were gen ...

. The front legs were five-toed, with an atrophied thumb, while the hind legs had only four toes. The tail was long and heavy. Another unusual characteristic for the artiodactyls was the presence of true claws, as confirmed by the shape of the

phalanges The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. ...

. The skull was long and thin, but the muzzle was rather short. There were two robust upper canines; these teeth were separated from the premolars by a long

diastema A diastema (plural diastemata, from Greek διάστημα, space) is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars. More colloquially, the condition ...

; the incisors were very small. The last lower

premolar The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...

had become identical to a true molar, while the upper one was nearly molar. This phenomenon is rare in artiodactyls, but is found in '' Dichodon'', where the fourth premolar is more complex than the molars. The elongated trunk was equipped with lumbar vertebrae similar to those of

cats The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of t ...

; the legs also resembled those of the felids. The distal end of the

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

, with its lower trochlea and the ''capitellum'' similar to that of

Anoplotheriidae Anoplotheriidae is an extinct family of even-toed ungulates ( order Artiodactyla). They were endemic to Western Europe during the Eocene and Oligocene epochs about 48—23 million years ago (Mya), existing for about 25 million years. They disapp ...

, indicates freedom of movement similar to that present within the

Cainotheriidae Cainotheriidae is an extinct family of artiodactyls known from the Late Eocene to Middle Miocene of Europe. They are mostly found preserved in karstic deposits. These animals were small in size, and generally did not exceed in height at the s ...

Classification

The genus ''Agriochoerus'' was described for the first time in 1850 by Joseph Leidy; the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''Agriochoerus antiquus'', whose fossils have been found in Eocene and Oligocene sediments of

Nebraska Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the southwe ...

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota people, Lakota and Dakota peo ...

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

and

Saskatchewan Saskatchewan ( ; ) is a Provinces and territories of Canada, province in Western Canada, western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on t ...

. Other species attributed to the same genus are ''A. gaudryi'', ''A. guyotianus'', ''A. crassus'', ''A. major'', ''A. maximus'', and ''A. minimus'', all coming from the Eocene–Oligocene of North America. ''Agriochoerus'' is the eponymous genus of the Agriochoeridae, a group of artiodactyl mammals similar to

Merycoidodontidae Merycoidodontoidea, sometimes called "oreodonts" or "ruminating hogs", is an extinct superfamily of prehistoric cud-chewing artiodactyls with short faces and fang-like canine teeth. As their name implies, some of the better known forms were gen ...

, but distinguishable from the latter for a series of characteristics of the skeleton and of the dentition. ''Agriochoerus'' appears to have been the most specialized agriochoerid.

Paleoecology

The

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

of the teeth indicates that ''Agriochoerus'' shows that this animal was herbivorous, even if the "feline" skeletal anatomy and the presence of claws (as opposed to hooves) are more reminiscent of carnivores. Some scholars have hypothesized that ''Agriochoerus'' was able to climb trees, due to the presence of strong claws; other scholars have proposed that ''Agriochoerus'' was able to dig burrows or excavate roots to feed on. Skeleton_of_Agriochoerus_antiquus

References

Oreodonts Paleogene mammals of North America Oligocene Artiodactyla Eocene Artiodactyla Clawed herbivores Prehistoric Artiodactyla genera {{paleo-eventoedungulate-stub