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Merycoidodontinae

Mammalia - Ungulata - Merycoidodontidae

Synonyms
Synonymy list
YearName and author
1850Eucrotaphus Leidy
1850Eucrotaphus jacksoni Leidy p. 90
1853Eucrotaphus jacksoni Leidy
1884Eucrotaphus Cope p. 513
1884Eucrotaphus jacksoni Cope p. 517
1890Oreodon jacksoni Scott
1902Merycoidodontinae Hay p. 665
1902Eucrotaphus Hay p. 666
1902Eucrotaphus jacksoni Hay p. 666
1906Eucrotaphus jacksoni Douglass p. 566
1937Eucrotaphus Thorpe p. 61
1937Eucrotaphus jacksoni Thorpe p. 61 figs. PI. I, figs. 13-15
1968Pseudogenetochoerus Schultz and Falkenbach
1968Merycoidodontinae Schultz and Falkenbach p. 24
1968Pseudogenetochoerus Schultz and Falkenbach p. 156 figs. figures 14-16, 19, 20, 22, 52
1996Merycoidodontinae Stevens and Stevens p. 512
1997Eucrotaphus McKenna and Bell p. 408
1998Eucrotaphus Lander
1998Eucrotaphus jacksoni Lander
2007Merycoidodontinae Stevens and Stevens p. 160

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

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 1968Skulls moderately small to medium in size; dolichocephalic to mesocephalic ; low to moderately high; supraoccipital wings with moderate lateral spread (not fan-shaped as in Miniochoerinae), extending posteriorly above and posterior to condyles ; exoccipital foramen round to oblong ; supraorbital foramina may be close together or distantly separated ( most examples with prominent anterior grooves); anterior nasal-maxilla contact in area above posterior border of CJ to anterior border of P1 ; orbits round to oblong ; lacrimal fossa deep to shallow; nasals with slight anterior retraction, posterior border with much variation (acute, obtuse, or truncated) ; zygomatic arch with inward notch posterior to orbits ; slight to prominent pit or depression on face above anterior premolars ; bulla small (minute) to well inflated, with variation in depth of hyoidal groove (prominent in early geologic forms, lost in latest forms) ; postglenoid process compressed anteroposteriorly with varying degrees of robustness and inward slope of external borders ; glenoid surface arched anteroposteriorly; palate projecting posteriorly to region of posterior border of M3 ; noticeable increase in depth of ramus anteroposteriorly; inferior border of ramus approximately straight to a point below and posterior to Ms, then with a noticeable downward curve; ascending ramus moderately high, wide anteroposteriorly, posterior border with prominent robust rim or
M. S. Stevens and J. B. Stevens 1996Medium-sized oreodonts primitively with narrow, high, and arched muzzles, steep premaxillae, Subnasal L./Nasal L. ratios averag- ing from 53% to 47%, deep preorbital fossae, infraor- bital foramina above P 2 , and small auditory bullae each with a deep hyoidal groove. Later species have lower and broader muzzles, more inclined premaxillae, smaller preorbital fossae, infraorbital foramina above P4, broad frontals, and progressively more inflated auditory bullae which lose the hyoidal groove. Dentally, the Merycoidodontinae remained conserva- tive throughout their history, with unreduced premolars 50-48% of the pl_P4;pl_M3 ratio (rounded averages; Table 3), an APM3/TM3 ratio that is primitively 1.0 or slightly less but increases to 1.18 in the youngest species (averages; Table 5), and with persistently brachydont-submesodont dentitions where the APM3/Ht. M3 ratio averages 1.80 to 1.53 (Table 4). Over time, the TM3/Ht. M3 ratio progressively decreases from 1.80 to 1.36 (Table 6). The Merycoi- dodontinae differ from Miniochoerinae by progres- sively larger size, lack of thinned enamel on the premolar-molar middle crests and selenes, and by inflated auditory bullae in species younger than earlier Orellan; and differ by grade only from Eporeodontinae by a usually larger size (species younger than Orellan), an arched, instead of a concave nasal profile, and complete absence of facial vacuities.