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Merychyus calaminthus
Taxonomy
Merychyus calaminthus was named by Jahns (1940). Its type specimen is CIT 1383, a partial skull (Partial skull with P3-M3), and it is a 3D body fossil. Its type locality is Tick Canyon (CIT 201), which is in an Arikareean fluvial siltstone/sandstone in the Tick Canyon Formation of California.
It was synonymized subjectively with Merychyus elegans by Kelly and Lander (1988); it was synonymized subjectively with Merychyus minimus by Lander (1998).
It was synonymized subjectively with Merychyus elegans by Kelly and Lander (1988); it was synonymized subjectively with Merychyus minimus by Lander (1998).
Synonyms
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Synonymy list
| Year | Name and author |
|---|---|
| 1940 | Merychyus calaminthus Jahns p. 187 figs. Plate 1, figures 2-3a; plates 2, 3 |
| 1947 | Merychyus calaminthus Schultz and Falkenbach p. 188 fig. 13 |
| 1947 | Merychyus crabilli Schultz and Falkenbach p. 189 figs. 1, 6, 13-17 |
| 1967 | Merychyus jahnsi Whistler p. 4 figs. Figure 1 |
| 1968 | Merychyus crabilli ziaensis Schultz and Falkenbach p. 377 figs. Figure 44 |
| 1974 | Merychyus calaminthus Woodburne et al. p. 18 figs. Text-fig. 5, A and B ; Table 1 |
| 1988 | Merychyus crabilli Kelly and Lander p. 8 |
| 2007 | Merychyus calaminthus Stevens and Stevens p. 164 |
| 2009 | Merychyus calaminthus Morgan et al. p. 95 |
| 2011 | Merychyus calaminthus Lander and Lindsay p. 221 fig. 5 |
| 2023 | Merychyus calaminthus Stevens et al. p. 37 figs. Figures 27-29; Appendix 2B; Table A9 |
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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.
†Merychyus calaminthus Jahns 1940
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Invalid names: Merychyus crabilli Schultz and Falkenbach 1947 [synonym], Merychyus jahnsi Whistler 1967 [synonym]
†Merychyus crabilli ziaensis Schultz and Falkenbach 1968
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| R. H. Jahns 1940 | The most mature specimens are slightly smaller than Merychyus delicatus, heretofore the smallest recorded species of the genus, and notably smaller than M. arenarum minimus and M. curtus. The slender build is.further indicated by the small eye socket, slender zygomata, and smallness of cranial region of the skull. The most diagnostic single character, however, is a pronounced ovoid antorbital fossa, at the anterior edge of which is a tiny facial vacuity. The dentition closely resembles that of M. delicatus, with uncrowded premolars and characteristic premolar pattern; the only notable character is a distinct spur projecting outward from the inner crescent of P4. | |
| C. B. Schultz and C. H. Falkenbach 1947 | SKULL: Small size; low and flat; supra- occipital wings widely spread, possibly less fan-shaped occipital region than in average Merychyus examples; brain case well inflated laterally with slight reduction of the post-orbital restriction; very short and low sagittal crest; wide frontals; orbits somewhat oblong with anteroposterior axis; lacrimal fossa large but shallow; prelacrimal vacuity small; zygomatic arch with a rounded inferior border, curving upward on both sides of the orbit (a large depression on the side of the face above the dental series causes the zygomatic arch to appear as if it rises from the face almost at the contact of the premaxilla and maxilla); infraorbital foramen above P 3 ; postglenoid process very thin anteroposteriorly, wide transversely, with sloping external and internal borders. (Characters based on immature and fragmentary material.)
MANDIBLE: Moderately heavy construction; gradual increase posteriorly in depth of ram us; posterior border of ascending ramus with inward curve. (Characters based on immature material.) DENTITION: Light; subhypsodont for a small Merychyus; superior premolars crowded, PLP 2 set at a slight angle to the alveolar border; external styles of molars moderately prominent. (Characters based on mature specimen.) LIMBS: Slender construction, approximating small Merychyus from the Great Plains. | |
| C. B. Schultz and C. H. Falkenbach 1947 (Merychyus crabilli) | SKULL:Smaller than that of M. minimus and considerably smaller than examples of M. siouxensis from the same formation; nasals light; prelacrimal vacuity very small; lacrimal fossa shallow, slightly deeper than in M. arenarum and M. minimus; infraorbital foramen above anterior portion of P4 ; post-glenoid process light; occipital condyles smaller than in examples of M. minimus and M. siouxensis; bulla well inflated with a somewhat flattened internal surface, large for size of the skull.
MANDIBLE: Light construction; inferior border with a gradual downward trend posteriorly; smaller than M. minimus and decidedly smaller than M. siouxensis. DENTITION:Superior and inferior series crowded, with less over-all length than in examples of M. minimus or M. siouxensis; molar series approximately equal in length to those of M. minimus. LIMBS: Short and light; smaller than examples of M. minimus and considerably smaller than examples of M. siouxensis (see figs. 15-17). | |
| D. P. Whistler 1967 (Merychyus jahnsi) | Smallest recognized species of the genus Merychyus, a number of measurements averaging 15 per cent smaller than M. (Merychyus) crabilli (Fig. 2); low flat skull, supraoccipital wings widely spread; shallow antorbital fossa, small prelacrimal vacuity with triangular outline; lightly constructed malar; paired infraorbital foramina above P3, superior molars subhypsodont. | |
| M. S. Stevens et al. 2023 | Smallest species of Merychyus (M1-3 length =28-38 mm); lightly built zygomatic arches, short nasals, wellinflated auditory bullae, a small facial vacuity located anterior toa shallow preorbital fossa, a well-inflated braincase, and a lessfan-shaped occipital crest |
Measurements
No measurements are available
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| Source: f = family, o = order, subc = subclass, c = class, subp = subphylum | |||||
| References: Carroll 1988, Hendy et al. 2009, Lillegraven 1979, Lander 1998, Nowak 1999 | |||||
Age range: base of the Early/Lower Hemingfordian to the top of the Harrisonian or 20.43000 to 18.50000 Ma
Collections (17 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Arikareean | USA (California) | Merychyus calaminthus (17851) Merychyus calaminthus, Merychyus jahnsi (type locality: 17852) | |
| Arikareean | USA (Oregon) | Merychyus calaminthus (188965) | |
| Arikareean | USA (Texas) | Merychyus calaminthus (178063) | |
| early Late Arikareean | USA (Arizona) | Merychyus calaminthus (157243 157244) | |
| late Late Arikareean | USA (Oregon) | Merychyus calaminthus (18013) | |
| Harrisonian | USA (Nebraska) | Merychyus crabilli (17806 17856) | |
| Harrisonian | USA (Wyoming) | Merychyus crabilli (17794 17801 17811 17853) | |
| Harrisonian | USA (Texas) | Merychyus sp. (17772) | |
| Early/Lower Miocene | USA (California) | Merychyus calaminthus (17765) | |
| Miocene | USA (New Mexico) | Merychyus crabilli (19130) | |
| Early/Lower Hemingfordian | USA (New Mexico) | Merychyus crabilli (19275) |