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Ustatochoerus major

Mammalia - Artiodactyla - Merycoidodontidae

Taxonomy
Merychyus major was named by Leidy (1858). Its type specimen is NM 439, a maxilla (Partial right maxilla with P3-M3), and it is a 3D body fossil. Its type locality is Niobrara River (coll. Hayden 1857), which is in a Miocene terrestrial horizon in the Loop Fork Formation of Nebraska.

It was recombined as Metoreodon major by Matthew (1924) and Thorpe (1937); it was recombined as Ustatochoerus major by Schultz and Falkenbach (1941), Schultz and Falkenbach (1947), Stevens and Stevens (1989), Voorhies (1990) and Stevens and Stevens (2007).

Synonymy list
YearName and author
1858Merychyus major Leidy p. 26
1884Merychyus major Cope p. 545
1924Metoreodon major Matthew
1937Metoreodon major Thorpe
1941Ustatochoerus major Schultz and Falkenbach p. 16
1947Ustatochoerus major Schultz and Falkenbach
1988Merychyus major Kelly and Lander
1989Ustatochoerus major Stevens and Stevens
1990Ustatochoerus major Voorhies
1998Merychyus major Lander
2007Ustatochoerus major Stevens and Stevens p. 166
2009Merychyus major Morgan et al.

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
phylumChordataHaeckel 1847
OlfactoresJefferies 1991
subphylumVertebrata
Gnathostomata()
Osteichthyes()
Sarcopterygii
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda()
Reptiliomorpha
Anthracosauria
Batrachosauria()
Cotylosauria()
RankNameAuthor
Amniota
Synapsida()
Therapsida()
infraorderCynodontia()
Epicynodontia
infraorderEucynodontia
Probainognathia
Mammaliamorpha
Mammaliaformes
classMammalia
orderArtiodactyla()
suborderTylopoda()
superfamilyOreodontoidea
familyMerycoidodontidaeThorpe 1923
subfamilyUstatochoerinae
genusUstatochoerus
speciesmajor()

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
C. B. Schultz and C. H. Falkenbach 1941SKULL.-Larger than that of U. profectus; elongated posterior to orbits; malar moderately deep; nasals short and retracted considerably more than those of U. profectus; anterior tip of nasals retracted to region above P 3 ; postglenoid process very large in comparison with that of U. profectus.
MANDIBLE.-Typical of genus; larger and more robust than in U. profectus; smaller and lighter than in U. californicus espanolensis.
DENTITION.-Well-developed cusps in superior and inferior premolars, more so than in U. medius; 'tendency for presence of cingula on superior molars; m- ferior premolars crowded and grooved on internal side.
LIMBS.-Longer and heavier than in examples of U. profectus.