PBDB Taxon

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Mesoreodon chelonyx

Mammalia - Merycoidodontidae

Taxonomy

Mesoreodon chelonyx was named by Scott (1893) [genotype]. It is the type species of Mesoreodon.

It was synonymized subjectively with Eporeodon major by Lander (1998).

Synonyms

Eucrotaphus montanus was named by Douglass (1907). Its type specimen is CM 907, a partial skeleton (an entire skull with the mandible, a pelvis, a sacrum, and nearly all the presacral vertebrae.), and it is a 3D body fossil. Its type locality is Stubb's Ferry, which is in a Whitneyan terrestrial horizon in Montana.

It was recombined as Eporeodon montanus by Thorpe (1924), Thorpe (1937), Scott (1940); it was recombined as Subdesmatochoerus montanus by Schultz and Falkenbach (1954); it was synonymized subjectively with Eporeodon major by Lander (1998); it was synonymized subjectively with Mesoreodon chelonyx by Stevens and Stevens (1996), Tabrum and Nichols (2001).
Mesoreodon danai was named by Koerner (1940). Its type locality is Fort Logan, which is in an Arikareean terrestrial horizon in Montana.

It was synonymized subjectively with Mesoreodon chelonyx by Schultz and Falkenbach (1949), Stevens and Stevens (1996); it was synonymized subjectively with Blickohyus auritus by Lander (1998).
Mesoreodon intermedius was named by Scott (1893).

It was synonymized subjectively with Mesoreodon chelonyx by Schultz and Falkenbach (1949), Stevens and Stevens (1996); it was synonymized subjectively with Eporeodon major by Lander (1998).
Mesoreodon laticeps was named by Loomis (1924) [misprint].

It was synonymized subjectively with Merycoides latidens by Thorpe (1937); it was synonymized subjectively with Mesoreodon chelonyx by Schultz and Falkenbach (1949).
Paramerycoidodon (Gregoryochoerus) meagherensis was named by Schultz and Falkenbach (1968). Its type specimen is YPM 13948, a partial skeleton, and it is a 3D body fossil.

It was recombined as Eporeodon meagherensis by Schultz and Falkenbach (1968); it was synonymized subjectively with Mesoreodon chelonyx by Stevens and Stevens (1996); it was synonymized subjectively with Eporeodon major by Lander (1998).

Synonymy list

Year	Name and author
1893	Mesoreodon chelonyx Scott p. 661
1893	Mesoreodon intermedius Scott p. 661
1902	Mesoreodon chelonyx Hay p. 667
1902	Mesoreodon intermedius Hay p. 667
1906	Mesoreodon chelonyx Douglass p. 566
1907	Eucrotaphus montanus Douglass p. 100
1924	Mesoreodon laticeps Loomis
1924	Eporeodon montanus Thorpe
1937	Eporeodon montanus Thorpe p. 80 figs. Fig. 40 ; PL IX, figs. 1-3
1937	Mesoreodon chelonyx Thorpe p. 98 figs. Fig. 65 PL IX, fig. 4; PI. XI, figs. 1-2
1937	Mesoreodon intermedius Thorpe p. 102 figs. PI. XI, fig. 3
1940	Mesoreodon danai Koerner
1940	Eporeodon montanus Scott p. 686
1949	Mesoreodon chelonyx Schultz and Falkenbach p. 140 figs. 15, 16, 18, 19, 26
1954	Subdesmatochoerus montanus Schultz and Falkenbach p. 220 figs. 19 - 21
1968	Eporeodon meagherensis Schultz and Falkenbach
1968	Paramerycoidodon (Gregoryochoerus) meagherensis Schultz and Falkenbach
1996	Mesoreodon chelonyx Stevens and Stevens
2007	Mesoreodon chelonyx Stevens and Stevens p. 160

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
—	Osteichthyes	()
subclass	Sarcopterygii	()
subclass	Dipnotetrapodomorpha	(Nelson 2006)
subclass	Tetrapodomorpha	()
—	Tetrapoda
—	Reptiliomorpha
—	Anthracosauria
subclass	Amphibiosauria	Kuhn 1967
—	Cotylosauria	()
—	Amniota
subclass	Synapsida
—	Therapsida	()
infraorder	Cynodontia	()

Rank	Name	Author
—	Mammaliamorpha
—	Mammaliaformes
class	Mammalia
—	Cladotheria
—	Zatheria
subclass	Tribosphenida	()
subclass	Theria
—	Eutheria	()
—	Placentalia
—	Boreoeutheria
—	Laurasiatheria
—	Scrotifera
—	Euungulata
—	Artiodactylamorpha
—	Artiodactyla	()
suborder	Tylopoda	()
family	Merycoidodontidae
subfamily	Merycoidodontinae
genus	Mesoreodon
species	chelonyx

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.

†Mesoreodon chelonyx Scott 1893

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Invalid names: Eporeodon meagherensis Schultz and Falkenbach 1968 [synonym], Eucrotaphus montanus Douglass 1907 [synonym], Mesoreodon danai Koerner 1940 [synonym], Mesoreodon intermedius Scott 1893 [synonym], Mesoreodon laticeps Loomis 1924 [synonym]

Diagnosis

Reference	Diagnosis
W. B. Scott 1893	Metapodials rather short and stout, ungual phalanges trowel-shaped and pointed.
W. B. Scott 1893 (Mesoreodon intermedius)	Metapodials slender and elongate, and ungual phalanges like those of Merychyus.
C. B. Schultz and C. H. Falkenbach 1949	SKULL: Medium size, with average examples equal to those of M. cheeki; sagittal crest prominent, moderately high; nasals without noticeable anterior retraction; posterior border of zygomatic arch similar to that of M. ckeeki but not extending posteriorly so far as in M. megalodonor M. megalodon sweeti; infraorbital foramen above P4; lacrimal fossa larger and deeper than in examples of M. cheeki; occipital condyles moderately large (considerable individual variation) ; paroccipital process not so wide at base as that in examples of M. cheeki, but with same angular position to the bulla as in that species; bulla inflated, somewhat oblong anteroposteriorly; postglenoid process heavy and wider laterally than anteroposteriorly. MANDIBLE:Similar in size and shape to examples of M. ckeeki. DENTITION: Similar to that of M. cheeki; tendency for slight diastema between P1 and Pl (not a constant character). LIMBS: Moderately short; shorter and lighter than those in Promerycochoerus;equal to examples of M. cheeki in size and construction.
C. B. Schultz and C. H. Falkenbach 1954 (Subdesmatochoerus montanus)	SKULL: Largest known form of genus; smaller than examples of Desmatochoerus and Pseudodesmatochoerus, larger than those of Prodesmatochoerus; sagittal crest light, high, and arched (more so than in examples of S. shannonensis), posterior portion slightly de- pressed; exoccipital vacuities larger than in S. socialis; nasals moderately light; zygomatic arch with more abrupt posterior rise than examples of S. shannonensis, more like those in S. socialis; malar deeper below orbit than in S. shannonensis; infraorbital foramen above P4 ; lacrimal fossa moderately large, very deep; slight depression posterior to infraorbital foramen; paroccipital process mod- erately light at base, with moderately down ward tapering, long axis of base paralleling longitudinal axis of skull; paroccipital process on external side of posterior portion of bulla (not directly posterior to bulla as in other examples of genus); bulla inflated, compressed laterally (similar, but larger than in examples of S. socialis dakotensis); post-glenoid process robust, wider than that in last-mentioned subspecies; posterior palate projecting farther posteriorly than in other forms of genus (palatal area partially restored in holotype). MANDIBLE: More robust and deeper than in examples of S. shannonensis (more like examples of Desmatochoerus from the Gering) ; inferior border of ramus arched, somewhat like those of Brachycrus but shallower anteriorly; ascending ramus high, wide anteroposteriorly; condyle large and moderately robust. DENTITION: Series more robust and of greater length than in examples of S. shannonensis; premolars crowded; p1-p3 and Pr P3 each set at angle to alveolar border; posterior external style of M3 more prominent than in other species of genus; P2 and P3 with anterior intermediate crest (P 1 may have crest, but not present on well-worn P1 of holotype). LIMBS:(Unknown).

Measurements

No measurements are available

Composition:

phosphaticsubp

Environment:

terrestrialo

Locomotion:

actively mobilec

Life habit:

ground dwellingf

Diet:

herbivoref

Reproduction:

viviparoussubc

Created:

2005-08-31 14:37:21

Modified:

2005-08-31 16:37:21

Source: f = family, o = order, subc = subclass, c = class, subp = subphylum

References: Hendy et al. 2009, Lander 1998, Carroll 1988, Nowak 1999, Lillegraven 1979

Age range: base of the Whitneyan to the top of the Geringian or 31.80000 to 24.70000 Ma

Collections (8 total)

Time interval	Ma	Country or state	Original ID and collection number
Whitneyan	31.8 - 29.5	USA (Montana)	Subdesmatochoerus montanus (17389)
Whitneyan	31.8 - 29.5	USA (Nebraska)	Paramerycoidodon meagherensis (17401)
Geringian	29.5 - 24.7	USA (Nebraska)	Paramerycoidodon meagherensis (17714)
Arikareean	29.5 - 18.5	USA (Wyoming)	Mesoreodon chelonyx (17667)
Arikareean	29.5 - 18.5	USA (Idaho)	Mesoreodon chelonyx (17586)
Arikareean	29.5 - 18.5	USA (Nebraska)	Paradesmatochoerus sandfordi (17470)
Arikareean	29.5 - 18.5	USA (Montana)	Eporeodon meagherensis, Mesoreodon chelonyx, Mesoreodon danai, Mesoreodon intermedius (17509) Mesoreodon chelonyx (17478)