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Ustatochoerus major
Taxonomy
Merychyus major was named by Leidy (1858). Its type specimen is NM 439, a maxilla (Partial right maxilla with P3-M3), and it is a 3D body fossil. Its type locality is Niobrara River (coll. Hayden 1857), which is in a Barstovian/Clarendonian terrestrial horizon in the Loup Fork Formation of Nebraska.
It was recombined as Metoreodon major by Matthew (1924) and Thorpe (1937); it was recombined as Ustatochoerus major by Schultz and Falkenbach (1941), Schultz and Falkenbach (1947), Stevens and Stevens (1989), Voorhies (1990), Stevens and Stevens (2007) and Stevens et al. (2023).
It was recombined as Metoreodon major by Matthew (1924) and Thorpe (1937); it was recombined as Ustatochoerus major by Schultz and Falkenbach (1941), Schultz and Falkenbach (1947), Stevens and Stevens (1989), Voorhies (1990), Stevens and Stevens (2007) and Stevens et al. (2023).
Synonyms
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Synonymy list
Year | Name and author |
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1858 | Merychyus major Leidy p. 26 |
1859 | Merychyus major major Leidy |
1873 | Merychyus major Leidy p. 201 |
1884 | Merychyus major Cope p. 545 |
1902 | Merychyus major Hay p. 669 |
1909 | Merychyus (Metoreodon) profectus Matthew and Cook p. 394 fig. 15 |
1912 | Metoreodon relictus profectus Cook p. 45 |
1917 | Metoreodon profectus Barbour and Cook p. 165 |
1924 | Ticholeptus profectus Loomis |
1924 | Metoreodon major Matthew |
1937 | Metoreodon major Thorpe p. 205 figs. PI. XXXVII, figs. 12-13 |
1937 | Metoreodon profectus Thorpe p. 209 figs. Figs. 152-153; PI. XXX; PI. XXXI, fig. 1 |
1941 | Ustatochoerus major Schultz and Falkenbach p. 16 |
1941 | Ustatochoerus major texanus Schultz and Falkenbach p. 22 |
1941 | Ustatochoerus profectus Schultz and Falkenbach p. 36 |
1941 | Ustatochoerus profectus espanolensis Schultz and Falkenbach p. 43 |
1941 | Ustatochoerus profectus studeri Schultz and Falkenbach p. 45 |
1941 | Ustatochoerus skinneri Schultz and Falkenbach p. 47 |
1941 | Ustatochoerus skinneri santacruzensis Schultz and Falkenbach p. 49 |
1942 | Metoreodon profectus Gregory p. 328 |
1947 | Ustatochoerus major Schultz and Falkenbach |
1947 | Ustatochoerus profectus Schultz and Falkenbach |
1949 | Ustatochoerus profectus Schultz and Falkenbach p. 81 |
1968 | Ustatochoerus profectus nevadaensis Schultz and Falkenbach p. 372 figs. Figure 45 |
1988 | Merychyus major Kelly and Lander |
1989 | Ustatochoerus major Stevens and Stevens |
1989 | Ustatochoerus profectus Stevens and Stevens |
1990 | Ustatochoerus major Voorhies |
1998 | Merychyus major Lander |
2007 | Ustatochoerus major Stevens and Stevens p. 166 |
2009 | Merychyus major Morgan et al. |
2009 | Merychyus major major Morgan et al. |
2023 | Ustatochoerus major Stevens et al. p. 119 figs. Figures 100-102; Appendix 12B; Table A40 |
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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.
†Ustatochoerus major Leidy 1858
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Invalid names: Merychyus (Metoreodon) profectus Matthew and Cook 1909 [synonym], Merychyus major major Leidy 1859 [invalid subgroup], Ustatochoerus major texanus Schultz and Falkenbach 1941 [invalid subgroup], Ustatochoerus profectus espanolensis Schultz and Falkenbach 1941 [invalid subgroup], Ustatochoerus profectus nevadaensis Schultz and Falkenbach 1968 [invalid subgroup], Ustatochoerus profectus studeri Schultz and Falkenbach 1941 [invalid subgroup], Ustatochoerus skinneri Schultz and Falkenbach 1941 [synonym], Ustatochoerus skinneri santacruzensis Schultz and Falkenbach 1941 [invalid subgroup]
Diagnosis
Reference | Diagnosis | |
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C. B. Schultz and C. H. Falkenbach 1941 | SKULL.-Larger than that of U. profectus; elongated posterior to orbits; malar moderately deep; nasals short and retracted considerably more than those of U. profectus; anterior tip of nasals retracted to region above P 3 ; postglenoid process very large in comparison with that of U. profectus.
MANDIBLE.-Typical of genus; larger and more robust than in U. profectus; smaller and lighter than in U. californicus espanolensis. DENTITION.-Well-developed cusps in superior and inferior premolars, more so than in U. medius; 'tendency for presence of cingula on superior molars; m- ferior premolars crowded and grooved on internal side. LIMBS.-Longer and heavier than in examples of U. profectus. | |
C. B. Schultz and C. H. Falkenbach 1941 (Ustatochoerus profectus) | SKULL.-Smaller than that of U. major and larger than that of U. medius; fan-shaped occipital region not as wide as in U. major; brain case slightly more inflated than in U. major; nasals shorter than in U. medius and decidedly longer than in U. major, and with less retraction than in the latter species; anterior tip of nasals retracted to region above P 2 ; paroccipital process long and tapered; postglenoid process not as heavy as in U. major.
MANDIBLE.-Typical of the genus, intermediate in size between those of U. medius and U. major. DENTITION.-Superior and inferior series intermediate in length between those of U. medius and U. major. LIMBs.-Shorter and lighter than in U. major; longer and heavier than in U. medius. | |
C. B. Schultz and C. H. Falkenbach 1941 (Ustatochoerus skinneri) | SKULL.-Differs from U. major, the nearest form, in somewhat smaller size; occipital flare not as wide; nasals much longer and less retracted (an- terior tip of nasals above region of P2); palate not extended as far posteriorly.
MANDIBLE.-Not quite as long as that of U. major. DENTITION.-Superior and inferior series of approximately same length as examples of U. major; inferior canine smaller and Pr lighter than in U. major; P4 usually lacks deep internal groove found in U. major. LIMBs.-Heavier and shorter than those of U. major; nearly same length as those of U. profectus. | |
M. S. Stevens et al. 2023 | Large Ustatochoerus (P2-M3 length = 110-125 mm; M1-3 length = 70-85 mm; p2-m3 length = 115-145 mm; m1-3 length = 77-100 mm), larger than U. medius but smaller than U. californicus, with much more shortened and retracted nasals than U. medius, reaching above the P3; large postglenoid process compared to U. medius. |