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Merychippus sejunctus

Mammalia - Perissodactyla - Equidae

Taxonomy
Protohippus sejunctus was named by Cope (1874) [also attributed to Cope 1884]. Its type specimen is AMNH 8291, a partial skeleton (Complete skull and lower jaws with entire dentition and parts of the skeleton associated, including the hind feet), and it is a 3D body fossil.

It was recombined as Merychippus (Protohippus) sejunctus by Stirton (1940); it was recombined as Pliohippus sejunctus by Quinn (1987); it was recombined as Stylonus sejunctus by Kelly and Lander (1988); it was recombined as Merychippus sejunctus by Hay (1902), Osborn (1904), Trouessart (1905), Gidley (1907), Matthew (1909), Cope and Matthew (1915), Osborn (1918), Matthew (1924), Hay (1930), Stirton (1933), Kelly (1995), MacFadden (1998) and Bravo-Cuevas and Ferrusquía-Villafranca (2006).

Synonymy list
YearName and author
1874Protohippus sejunctus Cope p. 15
1893Protohippus sejunctus Cope p. 25
1902Merychippus sejunctus Hay p. 618
1904Merychippus sejunctus Osborn
1905Merychippus sejunctus Trouessart
1907Merychippus sejunctus Gidley p. 891
1909Merychippus sejunctus Matthew
1915Merychippus sejunctus Cope and Matthew pp. Plate CL
1918Merychippus sejunctus Osborn p. 110 figs. Plates 11.1, 16.1,2,3, 19.1,2, 20,4&3, 48.1, 50.1,5, 53.3. Text Figs. 85, 85a, 86
1924Merychippus sejunctus Matthew
1930Merychippus sejunctus Hay
1933Merychippus sejunctus Stirton
1940Merychippus (Protohippus) sejunctus Stirton p. 182
1987Pliohippus sejunctus Quinn
1988Stylonus sejunctus Kelly and Lander
1995Merychippus sejunctus Kelly p. 26
1998Merychippus sejunctus MacFadden p. 547
2006Merychippus sejunctus Bravo-Cuevas and Ferrusquía-Villafranca p. 780

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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
Mammaliaformes
RankNameAuthor
classMammalia
Theriamorpha(Rowe 1993)
Theriiformes()
Trechnotheria
Cladotheria
Zatheria
subclassTribosphenida()
subclassTheria
Eutheria()
Placentalia
Boreoeutheria
Laurasiatheria
Scrotifera
Euungulata
Panperissodactyla
superorderPerissodactylamorpha
orderPerissodactyla()
superfamilyEquoidea
familyEquidae
subfamilyEquinae
genusMerychippus
speciessejunctus()

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.

Merychippus sejunctus Cope 1874
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Diagnosis
ReferenceDiagnosis
H. F. Osborn 1918(Matthew, 1913) (1) Size medium, pLm3 .123 (see Gidley); (2) protocone rather large, flattened oval,
united half way down; (3) fossette borders simple, fossette areas contracted; (4) pli caballin rudimentary or absent; (5) metastylid not separate in P2; (6) metastylid and metaconid pillars forming a rather narrow, double column; (7) heel of m3 broad, with internal fold. (8) Lachrymo-malar fossre broad, sessile, sub-united; (9) preorbital region rather short. (10) Ulnar shaft slender, united with radius except near proximal extremity; (11) metapodials and limb bones of moderate length and slenderness; (12) unguals rather narrow.
Measurements
No measurements are available
Composition: phosphaticsubp
Environment: terrestrialsubc
Locomotion: actively mobilec
Life habit: ground dwellingsubf
Diet: grazersubf
Diet 2: browsersubf
Reproduction: viviparoussubc
Created: 2005-08-31 14:56:53
Modified: 2005-08-31 16:56:53
Source: subf = subfamily, subc = subclass, c = class, subp = subphylum
References: Ji et al. 2002, Hendy et al. 2009, Carroll 1988, Nowak 1991, Lillegraven 1979, MacFadden 1998

Age range: base of the Hemingfordian to the top of the Barstovian or 20.43000 to 13.60000 Ma

Collections (6 total)


Time interval Ma Country or state Original ID and collection number
Miocene23.03 - 5.333USA (Montana) Merychippus sejunctus (19038)
Hemingfordian20.43 - 15.97USA (Colorado) Merychippus sejunctus (17908)
Barstovian15.97 - 13.6USA (Colorado) Merychippus sejunctus (18203)
Early/Lower Barstovian15.97 - 13.6USA (Texas) Merychippus sejunctus (18665)
Early/Lower Barstovian15.97 - 13.6Mexico (Oaxaca) Merychippus sejunctus (18735)
Middle Miocene15.97 - 11.608USA (Colorado) Merychippus sejunctus (18977)