Protoceratids

Protoceratidae is an extinct family of herbivorous North American artiodactyls (even-toed ungulates) that lived during the Eocene through Pliocene. While early members of the group were hornless, in later members males developed elaborate cranial ornamentation. They are variously allied with Ruminantia or Tylopoda.

Synthetoceras is an extinct genus of large protoceratid that was endemic to North America during the Late Miocene (12.5-4.7 million years ago), existing for approximately 7.8 million years. Fossils have been recovered from Nebraska and Texas. Two species have been described: S. tricornatus (the type species) and S. davisorum.

Protoceras ('first horn') is an extinct genus of Artiodactyla, of the family Protoceratidae, endemic to North America. It lived from the Oligocene to the Early Miocene 33.3—16.0 Ma, existing for approximately .

Leptoreodon is an extinct genus of small Artiodactyla, of the family Protoceratidae, endemic to North America. It lived during the Late Eocene 40.4—37.2 Ma, existing for approximately . Leptoreodon resembled deer, but were more closely related to camelids.

Paratoceras is an extinct genus of Artiodactyla, of the family Protoceratidae, endemic to North America. They lived during the Early to Middle Miocene, 20.4—10.3 Ma, existing for approximately . Paratoceras resembled deer, but were probably more closely related to chevrotains. In addition to having horns on the top of the head, they had a third horn on the snout.

Leptotragulus is an extinct genus of protoceratid, endemic to North America. It lived during the Middle Eocene epoch (Uintan to Chadronian stage) 40.2—33.9 Ma, existing for approximately .

Kyptoceras was a small extinct artiodactyl ungulate mammal of the family Protoceratidae, endemic to southeastern North America from the Miocene to Early Pliocene epoch 23.03—3.6 Ma, existing for approximately . The species name, amatorum, comes in honor of all amateur fossil collectors, including Frank Garcia (Ruskin, Florida) the amateur who found it and donated it to the Florida Museum of Natural History.

Toromeryx is a medium-sized extinct genus of Artiodactyla, of the family Protoceratidae, endemic to southwestern North America from the Eocene epoch (Late Uintan stage) 46.2—42 Ma, existing for approximately .

Poabromylus is an extinct genus of small artiodactyl, of the family Protoceratidae, endemic to North America. They lived during the Late Eocene 40.4–33.9 Ma, existing for approximately . They resembled deer but were more closely related to camelids.

Pseudoprotoceras is an extinct genus of Artiodactyla, of the family Protoceratidae, endemic to central North America. It lived during the Late Eocene 37.2—33.9 Ma, existing for approximately . Pseudoprotoceras resembled hornless deer, but were more closely related to camelids.

Trigenicus is an extinct genus of small artiodactyl in the family Protoceratidae, endemic to North America. It lived from the Late Eocene 37.2—33.9 Ma, existing for approximately . Trigenicus resembled deer, but were more closely related to camelids.