Trigenicus is a small extinct genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of Artiodactyla, of the family Protoceratidae

Protoceratidae

Protoceratidae is an extinct family of herbivorous North American artiodactyls that lived during the Eocene through Pliocene at around 46.2—4.9 Ma., existing for approximately .-Taxonomy:...

, endemic to North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 from the Late Eocene epoch (Chadronian

Chadronian

The Chadronian age within the North American Land Mammal Ages chronology is the North American faunal stage typically set from 38,000,000 to 33,900,000 years BP, a period of . It is usually considered to fall within the Eocene epoch...

 stage) 37.2—33.9 Ma, existing for approximately .

Taxonomy

Trigenicus was named by Douglass (1903) and treated as a synonym of Leptotragulus

Leptotragulus

Leptotragulus is a small extinct genus of Artiodactyla, of the family Protoceratidae, endemic to North America from the Eocene epoch 40.2—33.9 Ma, existing for approximately .-Taxonomy:...

 by Tabrum and Nichols 2001, but without discussion of Storer 1996. Its type is Trigenicus socialis. It was assigned to Protoceratidae

Protoceratidae

Protoceratidae is an extinct family of herbivorous North American artiodactyls that lived during the Eocene through Pliocene at around 46.2—4.9 Ma., existing for approximately .-Taxonomy:...

 by Douglass (1903) and Prothero (1998).

Morphology

Trigenicus resembled deer

Deer

Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...

. However they were more closely related to camelids

Camel

A camel is an even-toed ungulate within the genus Camelus, bearing distinctive fatty deposits known as humps on its back. There are two species of camels: the dromedary or Arabian camel has a single hump, and the bactrian has two humps. Dromedaries are native to the dry desert areas of West Asia,...

. In addition to having horns in the more usual place, protoceratids had additional, rostral horns above the orbital cavity

Orbit (anatomy)

In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...

.

Body mass

A single specimen of Trigenicus were measured by M. Mendoza, C. M. Janis, and P. Palmqvist for body mass. The specimen was determined to weigh:

• Specimen 1: 39.9 kg (88 lb)

Fossil distribution

Fossils have been recovered from:

• Toadstool Park, Chadron Formation, Sioux County, Nebraska
  Sioux County, Nebraska
  -National protected areas:* Agate Fossil Beds National Monument* Nebraska National Forest * Oglala National Grassland -Demographics:...
  
  
• Peanut Peak, Chadron Formation, Shannon County, South Dakota
  Shannon County, South Dakota
  As of the census of 2000, there were 12,466 people, 2,785 households, and 2,353 families residing in the county. The population density was 6 people per square mile . There were 3,123 housing units at an average density of 2 per square mile...
  
  
• Little Spring Gulch, Cook Ranch Formation, Beaverhead County, Montana
  Beaverhead County, Montana
  -National protected areas:* Beaverhead National Forest * Big Hole National Battlefield* Nez Perce National Historical Park * Red Rock Lakes National Wildlife Refuge-History:...
  
  
• Carnagh, Cypress Hills Formation
  Cypress Hills Formation
  The Cypress Hills Formation is a stratigraphical unit of Oligocene age in the Western Canadian Sedimentary Basin.It takes the name from the Cypress Hills, and was first described in outcrops on the slopes of the Cypress Hills by M.Y. Williams and W.S. Dyer in 1930...
  
  , Saskatchewan
  Saskatchewan
  Saskatchewan is a prairie province in Canada, which has an area of . Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota....