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Merychyus
Taxonomy
Merychyus was named by Leidy (1858). It is not extant. Its type is Merychyus elegans.
It was assigned to Merycoidodontinae by Hay (1902); to Oreodontidae by Cope (1884), Scott and Osborn (1890), Scott (1913); to Merycoidodontidae by Leidy (1858), Thorpe (1937), Lander (1998); to Ticholeptinae by Morgan et al. (2009), Lander and Lindsay (2011); and to Merychyinae by Schultz and Falkenbach (1947), Parris and Grandstaff (2003), Stevens and Stevens (2007), Stevens et al. (2023).
It was assigned to Merycoidodontinae by Hay (1902); to Oreodontidae by Cope (1884), Scott and Osborn (1890), Scott (1913); to Merycoidodontidae by Leidy (1858), Thorpe (1937), Lander (1998); to Ticholeptinae by Morgan et al. (2009), Lander and Lindsay (2011); and to Merychyinae by Schultz and Falkenbach (1947), Parris and Grandstaff (2003), Stevens and Stevens (2007), Stevens et al. (2023).
Synonymy list
| Year | Name and author |
|---|---|
| 1858 | Merychyus Leidy |
| 1884 | Merychyus Cope p. 535 |
| 1890 | Merychyus Scott and Osborn p. 72 |
| 1902 | Merychyus Hay p. 669 |
| 1913 | Merychyus Scott p. 361 |
| 1937 | Merychyus Thorpe p. 216 |
| 1947 | Merychyus Schultz and Falkenbach p. 171 figs. SF:igures 1-7, 13,14,15-17 |
| 1998 | Merychyus Lander |
| 2003 | Merychyus Parris and Grandstaff p. 63 |
| 2007 | Merychyus Stevens and Stevens p. 164 |
| 2009 | Merychyus Morgan et al. |
| 2011 | Merychyus Lander and Lindsay p. 221 |
| 2023 | Merychyus Stevens et al. p. 37 |
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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. †Merychyus Leidy 1858
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Subg. †Merychyus (Metoreodon) Matthew and Cook 1909
†Merychyus arenarum Cope 1884
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Invalid names: Merychyus arenarum leptorhynchus Cope 1884 [invalid subgroup], Merychyus euryops Cope 1899 [synonym]
†Merychyus calaminthus Jahns 1940
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Invalid names: Merychyus crabilli Schultz and Falkenbach 1947 [synonym], Merychyus crabilli ziaensis Schultz and Falkenbach 1968 [synonym], Merychyus jahnsi Whistler 1967 [synonym]
†Merychyus relictus Matthew and Cook 1909
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Invalid names: Merychyus (Metoreodon) relictus taylori Schultz and Falkenbach 1947 [invalid subgroup]
†Merychyus verrucomalus Stevens 1970
Invalid names: Merychyus (Metoreodon) relictus fletcheri Schultz and Falkenbach 1947 [invalid subgroup], Merychyus arenarum idahoensis Schultz and Falkenbach 1947 [invalid subgroup], Metoreodon Matthew and Cook 1909 [synonym]
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| C. B. Schultz and C. H. Falkenbach 1947 |
SKULL: Small, basal length ranging from 123 mm. to 178 mm.; mesocephalic; supra- occipital wings fan-shaped, widely spread, and incorporated in the occipital flare, but the flare not so pronounced as in the genus Ustatochoerus; exoccipital pits roundish in outline but not so large as in Ustatochoerus; ~ase of paroccipital process not completely mcorporated in the fan-shaped region as in Ustatochoerus or Merychyus (Metoreodon) (see fig. 14); sagittal crest prominent but not high; brain case inflated; zygomatic arch light to medium light; lacrimal fossa prom- inent in Harrison forms and shallow in later species; prelacrimal vacuity present; infra- orbital foramen either above posterior portion of pa or above P 4 ; nasals slightly retracted, extending posterior to the anterior of the orbits; premaxillae fused for a short distance; paroccipital process moderately long and heavy for size of skull; postglenoid process wide transversely, narrow anteroposteriorly, and long vertically; occipital condyles me- dium in size, but varying greatly in dimen- sions; bullae2 with various degrees of flatten- ing. MANDIBLE: Small; moderately deep for size of skull; inferior border nearly straight with a slight downward curve just posterior ,to Ma; condyle of moderate size; symphysis prominent, posterior point below region of PrP,. DENTITIONA:dvancedbrachyodonttosub- hypsodont; If and I~ approximately equal in size, with I~ larger; superior canines vary in size from small to large; P1 may be small or large. LIMBS:Light to moderately heavy. | |
| M. S. Stevens et al. 2023 | Medium-large sized merychyines with progressively more molarized premolars and more hypsodont cheek teeth in successive species. Fan-shaped occipital crests develop in the later species. |