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Mesoreodon
Taxonomy
Mesoreodon was named by Scott (1893). Its type is Mesoreodon chelonyx.
It was synonymized subjectively with Eporeodon by Lander (1998).
It was assigned to Oreodontidae by Scott (1913); to Merycoidodontidae by Thorpe (1937); to Promerycochoerinae by Schultz and Falkenbach (1949); and to Merycoidodontinae by Hay (1902), Stevens and Stevens (1996), Stevens and Stevens (2007).
It was synonymized subjectively with Eporeodon by Lander (1998).
It was assigned to Oreodontidae by Scott (1913); to Merycoidodontidae by Thorpe (1937); to Promerycochoerinae by Schultz and Falkenbach (1949); and to Merycoidodontinae by Hay (1902), Stevens and Stevens (1996), Stevens and Stevens (2007).
Species
M. chelonyx (syn. M. laticeps, Eucrotaphus montanus, M. danai, Eporeodon meagherensis, M. intermedius) (type species), M. floridensis, M. minor (syn. M. scotti, Pseudodesmatochoerus wascoensis, Desmatochoerus (Paradesmatochoerus) grangeri, Desmatochoerus (Paradesmatochoerus) monroecreekensis, Desmatochoerus (Paradesmatochoerus) sanfordi, Eporeodon cheeki, Desmatochoerus (Paradesmatochoerus) wyomingensis, Desmatochoerus macrosynaphus)
Synonymy list
| Year | Name and author |
|---|---|
| 1893 | Mesoreodon Scott p. 661 |
| 1902 | Mesoreodon Hay p. 667 |
| 1913 | Mesoreodon Scott p. 361 |
| 1937 | Mesoreodon Thorpe p. 97 |
| 1949 | Mesoreodon Schultz and Falkenbach p. 121 figs. 7, 15-20, 25-26 |
| 1996 | Mesoreodon Stevens and Stevens p. 532 |
| 2007 | Mesoreodon Stevens and Stevens p. 158 |
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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.
G. †Mesoreodon Scott 1893
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†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]
†Mesoreodon floridensis MacFadden and Morgan 2003
†Mesoreodon minor Douglass 1903
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Invalid names: Desmatochoerus (Paradesmatochoerus) grangeri Schultz and Falkenbach 1954 [synonym], Desmatochoerus (Paradesmatochoerus) monroecreekensis Schultz and Falkenbach 1954 [synonym], Desmatochoerus (Paradesmatochoerus) sanfordi Schultz and Falkenbach 1954 [synonym], Desmatochoerus (Paradesmatochoerus) wyomingensis Schultz and Falkenbach 1954 [synonym], Desmatochoerus macrosynaphus Riel 1964 [synonym], Eporeodon cheeki Schlaikjer 1934 [synonym], Mesoreodon scotti Schlaikjer 1934 [synonym], Pseudodesmatochoerus wascoensis Schultz and Falkenbach 1954 [synonym]
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| C. B. Schultz and C. H. Falkenbach 1949 | SKULL: Medium size; ranging in basal length from 211 to 259 mm. and in width from 131 to 191 mm.; smaller and shallower than in examples of Promerycochoerus, larger and higher than in examples of Promesoreodon; supraoccipital region similar to that of Promerycochoerus(protruding posteriorly beyond the occipital condyles with lateral wings not greatly expanded but extending consider- ably beyond the condyles); exoccipital with deep pits (or possibly foramina); sagittal crest long and high but less so than in Promerycochoerus and more so than in Promesoreodon; brain case wide and inflated; nasals long, moderately robust to robust and anterior bor- der from no retraction to slight retraction; anterior nasal-maxilla contact above P1; malar moderately deep below the orbit; zygomatic arch from moderately light to medium heavy
with highest point not extending upward to the plane of the sagittal crest, thus forming more of a half-circle than a U-shape (when viewed laterally); infraorbital foramen above PLJ>'; lacrimal fossa large, not so deep proportionately as in examples of Promesoreodon; slight depression on the side of the face above the premolar region; muzzle somewhat in flated; premaxillae joined for very short distance; occipital condyles moderately heavy; paroccipital process tapering gradually down- ward, adhering to the bulla, with axis at pronounced angle to the bulla; bulla inflated, from medium size to moderately large, later- ally compressed (suboval in outline), extending downward beyond the inferior border of the postglenoid process (see following dis- cussion); postglenoid process moderately robust, with shape varying from squarish to anteroposteriorly compressed; posterior palate projecting for short distance posterior of M3. MANDIBLE:Moderately robust; postsymphysis in area below Pa; symphysis strong, with a tubercle usually present at base of postsymphysis; ramus increasing in depth posteriorly; inferior ramal border slightly concave (not to the degree found in the genus Brachycrus), with gradual downward curve below the posterior portion of Ma; ascending ramus high, with slight inward curve of posterior border (similar to Promerycochoerus); condyle moderately large. DENTITION:Brachyodont (similar to Pro- merycochoerus,but less than in Promesoreo- don); C/ large; /C small;- P1large, somewhat spatulate shaped in outline; tendency towards slight diastema between P1 and pt (more pronounced in some species than in others); premolars varying in size, resulting in crowding of the premolar region in some individuals; average examples of the premolar series set more or less straight with the alveolar border; heel developed to varying degree on M8 ; external styles of superior molars prominent; anterior intermediate crest developed on P 1, P2, and pa in unworn or slightly worn premolar series (in Promerycochoerus this development on P 2 and P 1 only); posterior intermediate crest present on Pa (in Promerycochoerus this development weak); anterior basin or pit sometimes present on P'. LIMBS: Moderately short and moderately heavy; decidedly lighter and shorter than in examples of Promerycochoerus. | |
| M. S. Stevens and J. B. Stevens 1996 | Primitively, Mesoreodon has a generalized, mesocephalic cranium of Merycoidodon aspect, but ?M. minor is sub-brachycephalic (Table 7). Mesoreodon has inclined premaxillae, Subnasal L. averages about 47-52% of the Nasal L., a shallow pit- like preorbital fossae, an infraorbital foramen above p3_ p4, usually a generalized zygomatic arch but the posterior part of the arch in robust individuals of ?M.
minor is distinctly upturned, a relatively narrow braincase and posteriorly protracted nuchal crest, little reduced premolars with average pl_P41pl_M3 of 49- 48% (Table 3), the APM3/TM 3 averages 1.13 to 1.18 (Table 5), and the APM3/Ht. M3 averages 1.53 to 1.74 (Table 4), and the TM3/Ht. M3 ratio decreases (Table 6) from 1.46 (single measurement; oldest) to 1.36 (mean; youngest) as M3 becomes higher crowned relative to the width. Mesoreodon differs from Merycoi- dodon (Otarohyus) by larger size and relatively narrower and higher crowned teeth (particularly noticeable for our data in the significant difference between species of Mesoreodon and other species examined in this report in the APM3rrM3 ratio, a proportion distinctly stereotyped among the other taxa), otherwise very similar. M esoreodon differs from Eporeodon by larger size, smaller and more pit-like preorbital fossae, higher muzzle , more reduced premolars , more anteroposteriorly attenuated and slightly higher crowned molars, relatively smaller auditory bullae, and sometimes a more specialized, more upturned zygomatic arch. Mesoreodon differs from Desmatochoerus Thorpe (1921a) by smaller size. Mesoreodon differs from Desmato choerus and Hyp- siops Schultz and Falkenbach (1950) by a less special- ized, less upturned zygomatic arch. Mesoreodon differs from Hypsiops by relatively greater Nasal L., a shorter Subnasal L., less reduced premolars , and a broader M3. |