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Tapochoerus egressus

Mammalia - Artiodactyla - Diacodexeidae

Taxonomy
Hyopsodus egressus was named by Stock (1934). Its type specimen is LACM CIT 1590, a mandible (fragment of right ramus with P4-M3), and it is a 3D body fossil. Its type locality is Tapo Canyon (Upper), which is in an Uintan terrestrial horizon in the Sespe Formation of California. It is the type species of Tapochoerus.

It was recombined as Tapochoerus egressus by McKenna (1959), Gazin (1968), Golz (1976), Stucky (1998) and Theodor et al. (2007).

Synonymy list
YearName and author
1934Hyopsodus egressus Stock
1959Tapochoerus egressus McKenna p. 126 figs. Pl. 37
1968Tapochoerus egressus Gazin
1976Tapochoerus egressus Golz
1998Tapochoerus egressus Stucky
2007Tapochoerus egressus Theodor et al. p. 41

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
phylumChordataHaeckel 1847
subphylumVertebrata
superclassGnathostomata
Osteichthyes()
Sarcopterygii
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda()
Reptiliomorpha
Anthracosauria
Batrachosauria()
RankNameAuthor
Cotylosauria()
Amniota
Synapsida()
Therapsida()
infraorderCynodontia()
Epicynodontia
infraorderEucynodontia
Probainognathia
Mammaliamorpha
Mammaliaformes
classMammalia
orderArtiodactyla()
familyDiacodexeidae
genusTapochoerus
speciesegressus()

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. C. McKenna 1959Primitive dichobunid artiodactyl in which the teeth are more bunodont than selenodont; the hypocone is retained on M1 and/or M2, the metaconules are large but are neither hypertrophied nor markedly displaced and, when unworn, possess five posterior crests; there is neither a mesostyle nor ectoloph ribbing on M1 and/or M2, strong diastemata isolate the double-rooted p2; p3 is trenchant and lacks a metaconid; p4 is also trenchant but possesses a distinct entoconid and a metaconid which separates from the protoconid high on the crown; m1 has a strong paraconid separated from the metaconid but not as widely separated as in Antiacodon or Auxontodon, m2 has a variably separated paraconid, and m3 has a fused single lingual trigonid cusp; all the lower molars are elongate, with hypo- conulids closely similar to those of Hexacodus.