Protoceratidae is an extinct family of herbivorous

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 ...

n artiodactyls (even-toed ungulates) that lived during the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

through

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Ruminantia Ruminants are herbivorous grazing or browsing artiodactyls belonging to the suborder Ruminantia that are able to acquire nutrients from plant-based food by Enteric fermentation, fermenting it in a specialized stomach prior to digestion, principa ...

or Tylopoda.

Classification

Protoceratidae was erected by Othniel Charles Marsh in 1891, with the type genus '' Protoceras'' and assigned to the

Artiodactyla Artiodactyls are placental mammals belonging to the order (biology), order Artiodactyla ( , ). Typically, they are ungulates which bear weight equally on two (an even number) of their five toes (the third and fourth, often in the form of a hoof ...

. It was later assigned to

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 ...

, and more recently to

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

or Tylopoda. However, recently a relationship to chevrotains in the infraorder Tragulina has been proposed.

Morphology

When alive, protoceratids would have resembled

deer A deer (: deer) or true deer is a hoofed ruminant ungulate of the family Cervidae (informally the deer family). Cervidae is divided into subfamilies Cervinae (which includes, among others, muntjac, elk (wapiti), red deer, and fallow deer) ...

, though they were not directly related. Protoceratids ranged from 1 to 2 m in length, from about the size of a roe deer to an elk. Unlike many modern ungulates, they lacked cannon bones in their legs. Their dentition was similar to that of modern deer and cattle, suggesting they fed on tough grasses and similar foods, with a complex stomach similar to that of

camel A camel (from and () from Ancient Semitic: ''gāmāl'') is an even-toed ungulate in the genus ''Camelus'' that bears distinctive fatty deposits known as "humps" on its back. Camels have long been domesticated and, as livestock, they provid ...

s. At least some forms are believed to have lived in

herd A herd is a social group of certain animals of the same species, either wild or domestic. The form of collective animal behavior associated with this is called '' herding''. These animals are known as gregarious animals. The term ''herd'' ...

s. The most dramatic feature of the protoceratids, however, were the horns of the males. In addition to having horns in the more usual place, protoceratids had additional, rostral horns above their noses. These horns were either paired, as in '' Syndyoceras'', or fused at the base, and branching into two near the tip, as in '' Synthetoceras''. In life, the horns were probably covered with skin, much like the ossicones of a

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 ...

. The females were either hornless, or had far smaller horns than the males. Horns were therefore probably used in sexual display or competition for mates. In later forms, the horns were large enough to have been used in sparring between males, much as with the

antler Antlers are extensions of an animal's skull found in members of the Cervidae (deer) Family (biology), family. Antlers are a single structure composed of bone, cartilage, fibrous tissue, skin, nerves, and blood vessels. They are generally fo ...

s of some modern deer.

Genera by epoch

Eocene

* '' Heteromeryx'' * '' Leptoreodon'' * '' Leptotragulus'' * '' Poabromylus'' * '' Pseudoprotoceras'' * '' Toromeryx'' * '' Trigenicus''

Oligocene

* '' Protoceras''

Miocene

* '' Paratoceras'' * '' Lambdoceras'' * '' Prosynthetoceras'' * '' Synthetoceras'' * '' Syndyoceras''

Pliocene

* '' Kyptoceras''

References

{{Taxonbar, from=Q133821 Eocene Artiodactyla Miocene Artiodactyla Pliocene Artiodactyla Zanclean extinctions Prehistoric mammals of North America Prehistoric mammal families