PBDB Taxon

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Merycoidodon major

Mammalia - Merycoidodontidae

Taxonomy

Oreodon major was named by Leidy (1853) [also said to be 1854]. Its type specimen is USNM 19099, a maxilla, and it is a 3D body fossil.

It was recombined as Eporeodon major by Marsh (1875), Hay (1902), Thorpe (1921), Thorpe (1924), Thorpe (1937), Scott (1940), Galbreath (1953); it was recombined as Eucrotaphus major by Cope (1884); it was recombined as Eucrotaphus (Oreodon) major by Scott and Osborn (1887); it was recombined as Paramerycoidodon (Barbourochoerus) major by Schultz and Falkenbach (1968); it was recombined as Mesoreodon major by Fremd (1994), Lander (1998); it was recombined as Merycoidodon (Otarohyus) major by Stevens and Stevens (1996); it was recombined as Merycoidodon major by Stevens and Stevens (2007).

Synonyms

Merycoidodon (Blickohyus) lynchi was named by Schultz and Falkenbach (1968) [type of subgenus Blickohyus]. Its type specimen is F:AM 45297, a skull, and it is a 3D body fossil.

It was synonymized subjectively with Blickohyus auritus by Lander (1998); it was synonymized subjectively with Merycoidodon major by Stevens and Stevens (1996), Stevens et al. (2023).
Genetochoerus (Osbornohyus) chamberlaini was named by Schultz and Falkenbach (1968). Its type specimen is UNSM 28340, a partial skull, and it is a 3D body fossil. Its type locality is UNSM Mo-111 (Upper Whitney), which is in a Whitneyan terrestrial horizon in the Brule Formation of Nebraska.

It was synonymized subjectively with Merycoidodon major by Stevens and Stevens (1996).
Oreodon hybridus was named by Leidy (1869). Its type specimen is ANSP 10860, a partial skull, and it is a 3D body fossil.

It was recombined as Merycoidodon hybridus by Hay (1902); it was recombined as Eporeodon hybridus by Thorpe (1924); it was recombined as Eporeodon major hybridus by Thorpe (1937); it was synonymized subjectively with Eporeodon major by Scott (1940); it was recombined as Otionohyus (Otarohyus) hybridus by Schultz and Falkenbach (1968); it was synonymized subjectively with Merycoidodon major by Stevens and Stevens (1996); it was synonymized subjectively with Blickohyus auritus by Lander (1998).
Otionohyus (Otarohyus) alexi was named by Schultz and Falkenbach (1968). Its type specimen is F:AM 72060, a skull, and it is a 3D body fossil.

It was synonymized subjectively with Merycoidodon major by Stevens and Stevens (1996); it was synonymized subjectively with Eporeodon occidentalis by Lander (1998).
Paramerycoidodon (Gregoryochoerus) wanlessi was named by Schultz and Falkenbach (1968) [type of subgenus Gregorychoerus]. Its type specimen is F:AM 72014, a skull, and it is a 3D body fossil. It is the type species of Paramerycoidodon (Gregoryochoerus).

It was synonymized subjectively with Merycoidodon major by Stevens and Stevens (1996); it was synonymized subjectively with Blickohyus auritus by Lander (1998).
Promesoreodon scanloni was named by Schultz and Falkenbach (1949) [genotype]. Its type specimen is F:AM 45329, a partial skull (Partial skull with C/-P1 rt. and P2(br.) - M3 and partial mandible with i1-p2 rt. and PrMa,), and it is a 3D body fossil. It is the type species of Promesoreodon.

It was synonymized subjectively with Merycoidodon major by Stevens and Stevens (1996); it was synonymized subjectively with Eporeodon occidentalis by Lander (1998).
Subdesmatochoerus shannonensis was named by Schultz and Falkenbach (1954). Its type specimen is AMNH 1310, a partial skull (partial skull with I1-M3 (I3 rt., dP4 present on right side, P4 erupt. on left side)), and it is a 3D body fossil.

It was synonymized subjectively with Merycoidodon major by Stevens and Stevens (1996); it was synonymized subjectively with Eporeodon occidentalis by Lander (1998).

Synonymy list

Year	Name and author
1853	Oreodon major Leidy
1856	Oreodon major Leidy p. 164
1857	Oreodon major Leidy p. 89
1869	Oreodon hybridus Leidy
1873	Oreodon major Leidy p. 211
1873	Oreodon hybridus Leidy p. 212
1875	Eporeodon major Marsh p. 250
1884	Eucrotaphus major Cope p. 517
1887	Eucrotaphus (Oreodon) major Scott and Osborn p. 155
1902	Merycoidodon hybridus Hay p. 666
1902	Eporeodon major Hay p. 667
1921	Eporeodon major Thorpe
1924	Eporeodon hybridus Thorpe
1924	Eporeodon major Thorpe
1937	Eporeodon major Thorpe p. 74 figs. Fig. 7 ; PI. VI, figs. 1-3
1937	Eporeodon major hybridus Thorpe p. 77 figs. Fig. 38
1940	Eporeodon major Scott p. 679
1949	Promesoreodon scanloni Schultz and Falkenbach p. 152 figs. 21-25
1953	Eporeodon major Galbreath
1954	Subdesmatochoerus shannonensis Schultz and Falkenbach p. 223 figs. 19 - 21
1968	Genetochoerus (Osbornohyus) chamberlaini Schultz and Falkenbach
1968	Otionohyus (Otarohyus) alexi Schultz and Falkenbach
1968	Merycoidodon (Blickohyus) lynchi Schultz and Falkenbach p. 81 figs. Figures 4-6, 19-23, 52
1968	Paramerycoidodon (Barbourochoerus) major Schultz and Falkenbach p. 92 figs. igures 6-9, 1~23, 52
1968	Paramerycoidodon (Gregoryochoerus) wanlessi Schultz and Falkenbach p. 99 figs. Figures 6-9, 19, 52
1968	Otionohyus (Otarohyus) hybridus Schultz and Falkenbach p. 129 figs. Figures 11-13, 19-23
1968	Otionohyus (Otarohyus) alexi Schultz and Falkenbach p. 132 figs. F:igures 11-13, 52
1968	Genetochoerus (Osbornohyus) chamberlaini Schultz and Falkenbach p. 152 figs. Fgures 14-16
1994	Mesoreodon major Fremd
1996	Merycoidodon (Otarohyus) major Stevens and Stevens p. 529 figs. Figures 2D, 3D; Tables 1-7; Appendix B
1998	Mesoreodon major Lander
2007	Merycoidodon major Stevens and Stevens p. 160

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Diagnosis

Reference	Diagnosis
C. B. Schultz and C. H. Falkenbach 1949 (Promesoreodon scanloni)	SKULL: Small; see generic characters. MANDIBLE: Light; see generic characters. DENTITION:Brachyodont; series of less length than that in known species of Mesoreo- don; pa with anterior internal pits and P' with external anterior pit (not observable in well-worn specimens). LIMBS: Short and light, equal to small examples of Merycoidodon culbertsonii.
C. B. Schultz and C. H. Falkenbach 1954 (Subdesmatochoerus shannonensis)	SKULL: Slightly larger than in S. socialis, smaller than that of holotype of S. montanus; exoccipital vacuities moderately large, smaller than those in S. montanus; zygomatic arch with less abrupt posterior rise and inward notch below posterior aspect of orbit more pronounced than in S. socialis; paroccipital process heavier at base than in that species; bulla similar to that in S. socialis except for less prominent external posterior groove and pit for hyoid attachment. MANDIBLE: Slightly smaller than in holotype of S. montanus; larger than other forms of the genus. DENTITION: Series with average length greater than that in S. socialis; anterior intermediate crests on PLP 3 each well de- veloped (a remnant of an analogous crest indicated in unworn C/). LIMBS: Slightly larger and more robust than in S. socialis. (Known from fragmentary specimens only.)
M. S. Stevens and J. B. Stevens 1996	The cranial characterization is the same as for the genus-subgenus, but the skull trends toward massiveness, with broad frontals and muzzle, widely spread zygomatic arches, well inflated auditory bullae which lack distinct hyoidal grooves, and small and generally pit-like preorbital fossae. The Subnasal L. averages 51.5% of the Nasal L. (13 specimens), the pl_P4;pLM3 averages 48.4% (Table 3), the APM3/ TM3 ratio averages 1.02 (Table 5), the mean APM3/Ht. M3 ratio is 1.68 (Table 4), and TM3/Ht. M3 averages 1.63 (Table 6).Merycoidodonmajor differs from Merycoidodon bullatus by a substantially (on the average , means of M . bullatus lie 1.7 SDs below those of Merycoidodon major; basis: SDs of M. major), and in terms of measurement means, systematically , larger size (significant for all measurement means except that of Nasal L.), a usually broader P.O.C., slightly but significantly more reduced premolars, and the cranial features noted above,otherwise similar. Merycoidodon major differs from Mesoreodon chelonyx by a system- atically smaller size (means average about 0.9 SDs of M . major smaller; signific ant: pl-M3, pl_P4 , MI -M3, APM3s, Ht. M3, and Nasal L.), significantly less anteroposteriorly attenuated M3s, and slightly lower crowned teeth , otherwise very similar.