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Mesoreodon minor

Mammalia - Ungulata - Merycoidodontidae

Promerycochoerus minor was named by Douglass (1903). Its type specimen is CM 769, a partial skull (Anterior portion of skull with I2-M3, partial mandible with i1-m3, and fragments), and it is a 3D body fossil. Its type locality is Lower Cabbage Patch Beds, which is in an Arikareean terrestrial horizon in the Renova Formation of Montana.

It was recombined as Promerycochoerus hollandi minor by Thorpe (1937); it was recombined as Promerycochoerus (Pseudopromerycochoerus) minor by Schultz and Falkenbach (1949); it was recombined as Eporeodon minor by Lander (1998); it was recombined as Mesoreodon minor by Stevens and Stevens (1996), Tabrum and Nichols (2001) and Stevens and Stevens (2007).

Synonymy list
YearName and author
1903Promerycochoerus minor Douglass
1934Eporeodon cheeki Schlaikjer
1934Mesoreodon scotti Schlaikjer
1937Eporeodon major cheeki Thorpe p. 76 figs. PL VII; PI. XXXIX, fig. 2
1937Mesoreodon scotti Thorpe p. 103 figs. PI. XLIV, fig. 2
1937Promerycochoerus hollandi minor Thorpe p. 127 figs. Fig. 83; PI. XVI
1949Promerycochoerus (Pseudopromerycochoerus) minor Schultz and Falkenbach p. 124 figs. 10, 12
1949Mesoreodon cheeki Schultz and Falkenbach p. 135 figs. 7, 15, 17-19, 25
1949Mesoreodon cheeki scotti Schultz and Falkenbach p. 137 figs. Figures 15, 16, 18, 19, 25, 26
1954Desmatochoerus (Paradesmatochoerus) grangeri Schultz and Falkenbach p. 194 figs. 8-11, 24-25
1954Desmatochoerus (Paradesmatochoerus) monroecreekensis Schultz and Falkenbach p. 195 figs. 8 - 11
1954Desmatochoerus (Paradesmatochoerus) wyomingensis Schultz and Falkenbach p. 199 figs. 8 - 11, 18
1954Pseudodesmatochoerus wascoensis Schultz and Falkenbach p. 210 figs. 12 - 14
1961Mesoreodon cheeki Black
1964Desmatochoerus macrosynaphus Riel p. 3 figs. text-fig. no. 2; plates I, II
1970Promerycochoerus minor Macdonald
1996Mesoreodon minor Stevens and Stevens
1998Eporeodon minor Lander
2001Mesoreodon minor Tabrum and Nichols
2007Mesoreodon minor Stevens and Stevens p. 160

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phylumChordataHaeckel 1847
subclassDipnotetrapodomorpha(Nelson 2006)
orderUngulata(Linnaeus 1766)

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.

C. B. Schultz and C. H. Falkenbach 1949 (Mesoreodon cheeki)SKULL:Medium size, approximately equal to the average examples of M. chelonyx; lighter construction than that of M. megalodon sweeti; sagittal crest not so high as that of M. megalodon sweeti, but approximately equal to that of M. chelonyx; zygomatic arch light, approximately equal to that of M. chelonyx, but with posterior border not extending so far posteriorly as in M. megalodon sweeti; lacrimal fossa smaller and shallower than that in M. chelonyx; postglenoid process not so robust as in M. megalodon sweeti.
MANDIBLE: Similar to that of M. chelonyx; lighter then that of M. megalodon sweeti.
DENTITION:Length of dental series same as in M. chelonyx.
LIMBS: Equal in size to those of M. chelonyx, smaller than average examples of M. megalodon.
C. B. Schultz and C. H. Falkenbach 1949SKULL:Small, smallest known species of the subgenus; nasals slightly retracted; anterior nasal-maxilla contact above the region of P1; zygomatic arch light, extending posteriorly slightly beyond the postglenoid proc- ess; infraorbital foramen above posterior portion of P'; lacrimal fossa small and shallow; paroccipital process tapering rapidly downward; bulla of medium size, inflated, and suboval in outline; postglenoid process almost as wide laterally as anteroposteriorly and with a sloping external border.
MANDIBLE: Small; similar to that of examples of other species of the subgenus.
DENTITION: Series small, equal to that of P. (P.) minor pygmyus; smaller than in other species of the subgenus.
C. B. Schultz and C. H. Falkenbach 1954 (Desmatochoerus (Paradesmatochoerus) grangeri)SKULL: Medium size; longest known of subgenus; width similar to examples of D. (P.) monroecreekensis and D. (P.) wyomingensis, wider than those of D. sanfordi; submesocephalic; facial region longer than other ex- amples of subgenus; sagittal crest slightly higher than in other species of subgenus (not so high as examples of Desmatochoerus) ; exoccipital vacuities smaller and nasals with
more anterior retraction than in other species of subgenus; posterior portion of zygomatic arch robust, more so than in examples of D. (P.) monroecreekensis, infraorbital foramen above anterior portion of P 3 ; bulla with more lateral compression and posterior palate projecting more posteriorly than in other forms of subgenus.
MANDIBLE: Similar to those of other species of subgenus; postsymphysis below Pa; ascending ramus higher than in examples of D. (P.) wyomingensis.
DENTITION: Lighter than in other species of subgenus; superior series extending to the midline of orbit, not so far posteriorly as in other forms of subgenus.
LIMBS:Longer but similar to other examples of subgenus.
C. B. Schultz and C. H. Falkenbach 1954 (Desmatochoerus (Paradesmatochoerus) monroecreekensis)SKULL: Medium size [average examples equal in length to those of D. (P.) wyomingensis, slightly shorter than in D. (P.) grangeri]; more robust and wider than D. (P.) wyomingensis; submesocephalic; exoccipital vacuities intermediate in size between examples of D. (P.) wyomingensis and D. (P.) grangeri; anterior nasal-maxilla contact above P1; zygomatic arch moderately robust (lighter in female examples); infraorbital foramen above posterior portion of P3 to anterior portion of P4 ; paroccipital process more robust, bulla with less vertical height, and postglenoid process more massive and wider laterally than in D. (P.) wyomingensis.
MANDIBLE: Slightly more robust than in examples of D. (P.) wyomingensis; post-symphysis below posterior portion of Pa; ramus with tendency to be deeper below the anterior edge of Ma than later species.
DENTITION:Similar to examples of D. (P.) wyomingensis, lighter than in D. (P.) grangeri.
LIMBS: Similar to examples of D. (P.) wyomingensis; shorter than those of D. (P.) grangeri.
C. B. Schultz and C. H. Falkenbach 1954 (Desmatochoerus (Paradesmatochoerus) wyomingensis)SKULL: Approximately same length but narrower and lighter than examples of D. (P.) monroecreekensis, smaller than in the holotype of D. (P.) grangeri, larger than in D. (P.) sanfordi; dolichocephalic; exoccipital vacuities larger than in other known forms of subgenus; anterior nasal-maxilla contact above middle of P1 ; infraorbital foramen above pa; base of paroccipital process heavier, postglenoid process more robust, and bulla with greater vertical length than in examples of D. (P.) monroecreekensis.
MANDIBLE: Similar to examples of D. (P.) monroecreekensis, but lighter and with less depth below Ma; postsymphysis below P3.
DENTITION: Approximate size of examples of D. (P.) monroecreekensis; greater length and more robust than in D. (P.) grangeri and D. (P.) sanfordi.
LIMBS: Similar in size and form to exam- ples of D. (P.) monroecreekensis.
C. B. Schultz and C. H. Falkenbach 1954 (Pseudodesmatochoerus wascoensis)SKULL: Approximately same length as examples of P. hojfmani and P. milleri, larger than that of P. longiceps; mesocephalic, wider than other examples of genus; lower than in other species of genus, but not so low as examples of Mesoreodon (some of vertical compression of skull may be due to crushing); supraoccipital wings larger and with more lateral spread than in other species of genus; brain case inflated but slightly depressed; frontals wide; nasals more robust than usual in this genus, less anterior retraction than in P. hoffmani; anterior nasal-maxilla contact above anterior portion of P 1 ; less posterior rise of zygomatic arch than in other species of genus (arch incomplete); malar moderately deep below orbit; lacrimal fossa comparatively small but deep; occipital condyles more widely spread than in other species of genus; paroccipital process more massive and with less lateral compression than usual in this genus; bulla large, larger than in P. milleri, similar to that of P. hoffmani except for less lateral compression; postglenoid process robust; posterior palate projecting posteriorly beyond M 8 , not to extent found in the holotype of P. longiceps.
DENTITION: Series lighter than in examples of P. hoffmani and P. milleri, approximately equal to those of P. longiceps; series of less length than in two former species and longer than in latter.
S. J. Riel 1964 (Desmatochoerus macrosynaphus)Medium size; alveolar length of lower dental series approximately 135 mm; mandible very long and narrow; elongate symphysis extending to beneath Mi; ramus very shallow anterior to M 3 , increasing in depth posteriorly with abrupt downward curve of inferior border beneath M 3 ; dentition light as in D. (Paradesmatochoerus); superior premolars narrow; M3 with prom- inent metastyle; lower premolars not crowded; posterior acces- sory blade present on p3 ; anterior and posterior fossettes of p4 open lingually.
No measurements are available
Composition: phosphaticsubp
Environment: terrestrialo
Locomotion: actively mobilec
Life habit: ground dwellingf
Diet: herbivoref
Created: 2005-08-31 14:37:21
Modified: 2005-08-31 16:37:21
Source: f = family, o = order, c = class, subp = subphylum
References: Nowak 1999, Lander 1998, Carroll 1988, Hendy et al. 2009

Age range: base of the Whitneyan to the top of the Harrisonian or 33.30000 to 20.43000 Ma

Collections (25 total)

Time interval Ma Country or state Original ID and collection number
Whitneyan33.3 - 30.8USA (Nebraska) Desmatochoerus wyomingensis (17397)
Geringian30.8 - 26.3USA (Nebraska) Desmatochoerus wyomingensis (17595)
Geringian30.8 - 26.3USA (South Dakota) Desmatochoerus wyomingensis (17505 17656) Paradesmatochoerus wyomingensis (17592 17636)
Arikareean30.8 - 20.43USA (Wyoming) Desmatochoerus grangeri, Mesoreodon cheeki (17532) Desmatochoerus monroecreekensis, Mesoreodon scotti (17472) Desmatochoerus wyomingensis (17499 17524) Desmatochoerus wyomingensis, Mesoreodon cheeki (17727) Eporeodon cheeki (17667) Mesoreodon cheeki (17666 17686)
Arikareean30.8 - 20.43USA (Nebraska) Desmatochoerus wyomingensis (17522 17602) Mesoreodon cheeki (17604) Paradesmatochoerus wyomingensis (17470)
Arikareean30.8 - 20.43USA (South Dakota) Desmatochoerus wyomingensis (17533)
Arikareean30.8 - 20.43USA (Montana) Desmatochoerus macrosynaphus, Mesoreodon minor (type locality: 17540)
Harrisonian24.8 - 20.43USA (Wyoming) Promerycochoerus minor (17798)
Harrisonian24.8 - 20.43USA (South Dakota) Desmatochoerus wyomingensis (17745) Promerycochoerus minor (17457 17458 17751)