Protoceratidae

Protoceratids Temporal range: Middle Eocene–Early Pliocene PreꞒ Ꞓ O S D C P T J K Pg N [1]
Synthetoceras
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Artiodactyla
Suborder:	Cetruminantia
(unranked)	Ruminantiamorpha
(unranked)	Ruminantia
Infraorder:	Tragulina
Family:	†Protoceratidae
Subfamilies and Genera
†Leptotragulinae (same as Protoceratid) †Heteromeryx †Leptoreodon †Leptotragulus †Poabromylus †Toromeryx †Trigenicus †Protoceratinae †Paratoceras †Protoceras †Pseudoprotoceras †Synthetoceratinae †Kyptoceras †Lambdoceras †Prosynthetoceras †Synthetoceras †Syndyoceras
Range of Protoceratidae based on fossil record.

Protoceratidae is an extinct family of herbivorous North American artiodactyls (even-toed ungulates) that lived during the Eocene through Pliocene at around 46.2—4.9 Mya, existing for about 41 million years.^[2]

Taxonomy

The Protoceratidae were named by Marsh (1891). The type is Protoceras. It was assigned to Pecora by Cook in 1934; to Ruminantia by Thurmond and Jones (1981) and Spaulding et al. (2009); to Tylopoda by Carroll and by Webb et al. in 2003. It was assigned to Artiodactyla by Marsh (1891), Hulbert and Whitmore (2006) and Prothero and Ludtke (2007).^[3][4][5][6] It was assigned to the infraorder Tragulina by Spaulding et al., 2009.^[7]

Morphology

When alive, the living protoceratids would have probably resembled deer, though neither 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 camels. At least some forms are believed to have lived in herds.^[8]

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 females were either hornless, or had far smaller horns than the males, and 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 antlers of some modern deer.^[9]

Genera by epoch

Eocene

• Heteromeryx
• Leptoreodon
• Leptotragulus
• Poabromylus
• Toromeryx
• Trigenicus

Miocene

• Paratoceras
• Protoceras
• Kyptoceras
• Lambdoceras
• Prosynthetoceras
• Pseudoprotoceras
• Synthetoceras
• Syndyoceras

References