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Paramerychyus harrisonensis

Mammalia - Merycoidodontidae

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) and Stevens et al. (2023).

Synonyms
Synonymy list
YearName and author
1907Merychyus harrisonensis Peterson
1923Ticholeptus harrisonensis Loomis p. 227 figs. fig. 5
1924Merychyus siouxensis Loomis
1935Merychyus harrisonensis Schlaikjer
1937Merychyus harrisonensis Thorpe p. 229 figs. Figs. 166-168
1937Merychyus siouxensis Thorpe p. 232 figs. Fig. 169; PI. XXXIV, figs. 5-6
1947Merychyus siouxensis Schultz and Falkenbach p. 223 figs. 1, 7, 13, 15-17
1947Paramerychyus harrisonensis Schultz and Falkenbach p. 248 figs. 1, 9
1998Merycoides harrisonensis Lander
2007Paramerychyus harrisonensis Stevens and Stevens p. 164
2023Paramerychyus harrisonensis Stevens et al. p. 48 figs. Figures 34-35; Appendix 3A; Table A16

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RankNameAuthor
kingdomAnimalia()
Bilateria
EubilateriaAx 1987
Deuterostomia
phylumChordataHaeckel 1874
subphylumVertebrata
superclassGnathostomata
Osteichthyes()
subclassSarcopterygii()
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda
Reptiliomorpha
Anthracosauria
subclassAmphibiosauriaKuhn 1967
Cotylosauria()
Amniota
subclassSynapsida
Therapsida()
infraorderCynodontia()
Mammaliamorpha
RankNameAuthor
Mammaliaformes
classMammalia
Theriamorpha(Rowe 1993)
Theriiformes()
Trechnotheria
Cladotheria
Zatheria
subclassTribosphenida()
subclassTheria
Eutheria()
Placentalia
Boreoeutheria
Laurasiatheria
Scrotifera
Euungulata
Artiodactylamorpha
Artiodactyla()
familyMerycoidodontidae
subfamilyMerychyinae
genusParamerychyus
speciesharrisonensis()

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: Merychyus siouxensis Loomis 1924 [synonym]
Diagnosis
ReferenceDiagnosis
C. B. Schultz and C. H. Falkenbach 1947SKULL: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. 2023Medium-sized (M1-3 length = 43-50 mm) merychyines with relatively low-crowned cheek teeth compared to Merychyus.
Measurements
No measurements are available
Composition: phosphaticsubp
Environment: terrestrialo
Locomotion: actively mobilec
Life habit: ground dwellingf
Diet: herbivoref
Reproduction: viviparoussubc
Created: 2005-08-31 14:37:21
Modified: 2005-08-31 16:37:21
Source: f = family, o = order, subc = subclass, c = class, subp = subphylum
References: Lillegraven 1979, Lander 1998, Hendy et al. 2009, Carroll 1988, Nowak 1999

Age range: base of the Monroecreekian to the top of the Harrisonian or 26.30000 to 18.50000 Ma

Collections (13 total)


Time interval Ma Country or state Original ID and collection number
Monroecreekian26.3 - 24.8USA (South Dakota) Merychyus siouxensis (17723)
Harrisonian24.8 - 18.5USA (Nebraska) Merychyus siouxensis (17704 17733 17741 17843 28043)
Harrisonian24.8 - 18.5USA (Montana) Merychyus siouxensis (17861)
Harrisonian24.8 - 18.5USA (Wyoming) Merychyus harrisonensis (type locality: 17853) Merychyus siouxensis (17798 17801 17811) Merychyus siouxensis, Paramerychyus harrisonensis (17794)
Harrisonian24.8 - 18.5USA (Texas) Phenacocoelus leptoscelos (17767)