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Paramerychyus harrisonensis
Taxonomy
Merychyus harrisonensis was named by Peterson (1907). Its type specimen is CM 1341, a partial skull (a fairly well preserved skull which has been somewhat crushed vertically and is without the lower jaws), and it is a 3D body fossil. Its type locality is Van Tassel (Lower), which is in a Harrisonian terrestrial horizon in Wyoming. It is the type species of Paramerychyus.
It was recombined as Ticholeptus harrisonensis by Loomis (1923); it was recombined as Merycoides harrisonensis by Lander (1998); it was recombined as Paramerychyus harrisonensis by Schultz and Falkenbach (1947), Stevens and Stevens (2007), Stevens et al. (2023).
It was recombined as Ticholeptus harrisonensis by Loomis (1923); it was recombined as Merycoides harrisonensis by Lander (1998); it was recombined as Paramerychyus harrisonensis by Schultz and Falkenbach (1947), Stevens and Stevens (2007), Stevens et al. (2023).
Synonyms
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Synonymy list
| Year | Name and author |
|---|---|
| 1907 | Merychyus harrisonensis Peterson |
| 1923 | Ticholeptus harrisonensis Loomis p. 227 figs. fig. 5 |
| 1924 | Eporeodon relictus Loomis |
| 1924 | Merychyus siouxensis Loomis |
| 1935 | Merychyus harrisonensis Schlaikjer |
| 1937 | Eporeodon major relictus Thorpe p. 78 figs. Fig. 39; PI. VI, figs. 4-5 |
| 1937 | Merychyus harrisonensis Thorpe p. 229 figs. Figs. 166-168 |
| 1937 | Merychyus siouxensis Thorpe p. 232 figs. Fig. 169; PI. XXXIV, figs. 5-6 |
| 1947 | Merychyus siouxensis Schultz and Falkenbach p. 223 figs. 1, 7, 13, 15-17 |
| 1947 | Paramerychyus harrisonensis Schultz and Falkenbach p. 248 figs. 1, 9 |
| 1947 | Paramerychyus relictus Schultz and Falkenbach p. 249 figs. 1, 10, 14 |
| 1998 | Merycoides harrisonensis Lander |
| 1998 | Merycoides relictus Lander |
| 2007 | Paramerychyus harrisonensis Stevens and Stevens p. 164 |
| 2023 | Paramerychyus harrisonensis Stevens et al. p. 48 figs. Figures 34-35; Appendix 3A; Table A16 |
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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.
†Paramerychyus harrisonensis Peterson 1907
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Invalid names: Eporeodon relictus Loomis 1924 [synonym], Merychyus siouxensis Loomis 1924 [synonym]
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| C. B. Schultz and C. H. Falkenbach 1947 (Paramerychyus relictus) | SKULL: Slightly larger than known examples of P. harrisonensis and Eporeodon occidentalis; small but deep lacrimal fossa; prelacrimal vacuity questionably present; posterior border of nasals extended beyond the anterior line of the orbits; infraorbital foramen above the posterior border of P3; postglenoid process slightly more robust than in examples of P. harrisonensis; orbits slightly oval in outline, axis anteroposterior to skull, looking forward and outward; malar robust, inferior border slightly arched; external auditory meatus opening more outwardly than posteriorly.
MANDIBLE: Unknown. DENTITION: Series slightly longer and premolars larger than examples of P. harrisonensis; premolars set at a slight angle to alveolar border. LIMBS:Unknown. | |
| C. B. Schultz and C. H. Falkenbach 1947 | SKULL:Larger than any known examples of Merychyus; smaller than known specimens of Ticholeptus; approximate size of P. relictus; lacrimal fossa moderately large and deep; prelacrimal vacuity present (in the holotype the very large prelacrimal vacuity may be due to damage of the area; in the referred skull the vacuity is much smaller); malar moderately robust, with a slight but gradual upward trend posteriorly; zygomatic arch of medium construction with shallow rise posteriorly; orbits round, looking forward and upward; postorbital pillar quite heavy; bulla covering large area (Peterson described the bulla as "flask-like in form with a conical swelling on the posterior-external surface"); palatal surface vaulted.
MANDIBLE:Unknown. DENTITION:C/ heavy but not long; pre- molars not crowded; external styles of molars prominent. LIMBS: Unknown. | |
| C. B. Schultz and C. H. Falkenbach 1947 (Merychyus siouxensis) | SKULL: Larger than that of M. approximate size of large examples of M. arenarum; nasals heavier than those of M. crabilli; lacrimal fossa deep and large; pre-lacrimal vacuity moderately large; post- glenoid process decidedly heavier than that of M. crabilli; occipital condyles moderately large, larger than in M. crabilli,·bulla large and well inflated.
MANDIBLE: :Larger than that of M.crabilli. DENTITION: Superior and inferior series decidedly longer and heavier than those of M. crabilli; closer to those of M. arenarum. LIMBS:Decidedly longer and heavier than those of M. crabilli. | |
| M. S. Stevens et al. 2023 | Medium-sized (M1-3 length = 43-50 mm) merychyines with relatively low-crowned cheek teeth compared to Merychyus. |
Measurements
No measurements are available
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| Source: f = family, o = order, subc = subclass, c = class, subp = subphylum | |||||
| References: Lander 1998, Carroll 1988, Hendy et al. 2009, Lillegraven 1979, Nowak 1999 | |||||
Age range: base of the Monroecreekian to the top of the Harrisonian or 24.70000 to 18.50000 Ma
Collections (14 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Monroecreekian | USA (South Dakota) | Merychyus siouxensis (17723) | |
| Monroecreekian - Harrisonian | USA (Nebraska) | Merychyus siouxensis (17704) | |
| Harrisonian | USA (Wyoming) | Merychyus harrisonensis (type locality: 17853) Merychyus siouxensis (17798 17801 17811) Merychyus siouxensis, Paramerychyus harrisonensis (17794) | |
| Harrisonian | USA (Nebraska) | Merychyus siouxensis (17733 17741 17843 28043) | |
| Harrisonian | USA (Montana) | Merychyus siouxensis (17861) | |
| Harrisonian | USA (South Dakota) | Eporeodon relictus (17743) | |
| Harrisonian | USA (Texas) | Phenacocoelus leptoscelos (17767) |