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Merycoidodontidae (oreodont)

Mammalia - Ungulata - Merycoidodontidae

Synonyms
Synonymy list
YearName and author
1869Oreodontidae Leidy
1884Oreodontidae Cope p. 503
1889Oreodontidae Cope p. 876
1891Oreodontidae Cope p. 21
1910Oreodontidae Gregory p. 466
1912Merycoidodontidae Cook p. 45
1937Merycoidodontidae Thorpe p. 31
1940Merycoidodontidae Scott p. 648
1950Phenacocoelinae Schultz and Falkenbach p. 95
1954Desmatochoerinae Schultz and Falkenbach p. 153
1969Merycoidodontidae Ferrusquia-Villafranca
1969Merycoidodontidae Stevens et al. p. 26
1969Phenacocoelinae Stevens et al. p. 26
1996Merycoidodontidae Stevens and Stevens p. 510
1996Phenacocoelinae Stevens and Stevens p. 510
1997Oreodontidae McKenna and Bell p. 408
1998Merycoidodontidae Lander
2003Merycoidodontidae Parris and Grandstaff p. 63
2009Oreodontidae Morgan et al.
2011Oreodontidae Lander and Lindsay p. 221

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
phylumChordataHaeckel 1847
subphylumVertebrata
superclassGnathostomata
Osteichthyes()
Sarcopterygii
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda()
Reptiliomorpha
Anthracosauria
Batrachosauria()
Cotylosauria()
RankNameAuthor
Amniota
Synapsida()
Therapsida()
infraorderCynodontia()
Epicynodontia
infraorderEucynodontia
Probainognathia
Mammaliamorpha
Mammaliaformes
classMammalia
subclassTribosphenida()
infraclassEutheria()
orderUngulata(Linnaeus 1766)
orderArtiodactyla()
familyMerycoidodontidae
familyMerycoidodontidae

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Diagnosis
ReferenceDiagnosis
M. S. Stevens and J. B. Stevens 1996Oreodonts are suiform, selenodont artiodactyls that differ from most Agriocho- eridae by lack of a divided P4para-metacone, usual absence of molar labial ribs, the posterior arm of the protoselene usually directed medially and deeply into the median valley between the protocone and hypocone, usual absence of protoconules, and a usually closed postorbital. The Merycoidodontidae usually lack diastema (except those to receive the caniform teeth), have a full dental series of 13/3, Cl/1, P4/4, and M3/3, an incisiform lower canine, caniform Pt, and molars with W-shaped ectolophs.
Oreodont crania primitively have rather steep premaxillae, usually short Subnasal L. and a strongly convex nasal profile, but the profile becomes progres- sively straighter or more concave, and the Subnasal L. increases in some genera as the nasal notch migrates posteriorly. One genus firmly coalesces the rostrum ventral to the nasal aperture which causes the external nares to migrate posteriorly , and three genera greatly shorten the length of the nasal bones. Oreodont skulls are usually mesocephalic but certain groups become more brachycephalic, and one group becomes quite dolichocephalic. The orbits are situated in the mid- cranial region, and are primitively located relatively low on the sides of the face. Facial vacuities are absent in primitive species but are characteristic of numerous derived genera. The zygoma are usually unspecialized but become massively upturned in several taxa. The nuchal crest is primitively narrow and protracted strongly posteriorly, but the crest becomes less protracted and considerably expanded laterally in some specialized forms and a sagittal table may develop. Some genera progressively either develop or reduce the depth of the preorbital fossae, and auditory bullae vary from small to notably enlarged. Oreodont lower jaws consistently have a greatly enlarged, rounded angular region that is not much expanded below the ventral border of the horizontal ramus.