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Hypsiops brachymelis

Mammalia - Merycoidodontidae

Taxonomy
Ticholeptus brachymelis was named by Douglass (1907). Its type specimen is AMNH 9731, a partial skeleton (A nearly complete skull with the mandible, the cervical and lumbar vertebrae, nine or ten dorsal vertebrae part of which are incomplete, and the greater portion), and it is a 3D body fossil. Its type locality is North Boulder Valley, which is in a Harrisonian terrestrial horizon in the Renova Formation of Montana. It is the type species of Hypsiops.

It was synonymized subjectively with Hypsiops breviceps by Lander (1998) and Tabrum and Nichols (2001); it was recombined as Hypsiops brachymelis by Schultz and Falkenbach (1950) and Stevens et al. (2023).

Synonyms
Synonymy list
YearName and author
1907Ticholeptus breviceps Douglass p. 106
1907Ticholeptus brachymelis Douglass p. 815 figs. 6, 7
1923Ticholeptus petersoni Loomis
1937Ticholeptus brachymelis Thorpe p. 189 figs. Fig. 138; PI. XXIX, figs. 3-4
1937Ticholeptus breviceps Thorpe p. 190 figs. Fig. 139j PI. XXVIII, figs. 3-5
1937Ticholeptus petersoni Thorpe p. 193 figs. Figs. 5, 141; PL XLVII, fig. 2
1950Hypsiops brachymelis Schultz and Falkenbach p. 116 figs. 4-6, 11, 13-15
1950Hypsiops brachymelis petersoni Schultz and Falkenbach p. 118 figs. 7, 11, 14, 157, 11, 14, 15.
1950Hypsiops breviceps Schultz and Falkenbach p. 120 figs. 4-6, 12-15
1998Hypsiops breviceps Lander
2001Hypsiops breviceps Tabrum and Nichols
2007Hypsiops breviceps Stevens and Stevens p. 160
2023Hypsiops brachymelis Stevens et al. p. 82 figs. Figure 67; Appendix 8A; Table A28

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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
subfamilyMerycochoerinae
genusHypsiops
speciesbrachymelis()

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.

Hypsiops brachymelis Douglass 1907
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Invalid names: Ticholeptus breviceps Douglass 1907 [synonym], Ticholeptus petersoni Loomis 1923 [synonym]
Diagnosis
ReferenceDiagnosis
E. Douglass 1907Skull high in proportion to length. Greatest height to greatest length, 157mm.: 257mm. = 61: 100 or approximately 3/5 Forehead only moderately broad; upper anteroposterior contour of skull nearly straight; sagittal crest short and not high; orbit small; zygomatic arches deep under the orbit, ascending posteriorly; squamosal portion of arch not heavy; nasals shortened; horizontal ramus of mandible moderately deep,uniform in height from p3 to m3; premolar teeth not long or high; molars moderately hypsodont; proportion of length of upper premolar to molar series= 48mm.: 60mm.= 80:100= 4/5,;lower molar to premolar series=49 mm.: 64 mm. = 76.5 :100; limbs and feet short. The premaxillaries are coossified for a distance of 12cm. The upper portion of the anterior narial opening is large and broadly rounded, the borders only moderately steep. The narials are abbreviated. The infra orbital foramen opens above the anterior portion of p-4. The malomaxillary ridge is heavy and the lachrymal pit deep. The malar is deep beneath the orbits and ascends backward. The squamosal portion of the zygomatic arch is heavy. The forehead is not extremely broad, neither is the occiput. The exoccipitals and the paroccipital processes are moderately expanded laterally. The internal portions of the latter, behind the tympanic bullae,are thickened antero-posteriorly. The bullae are quite large. The external auditory meatus is a long, straight tube directed upward more than outward or backward. The angle of the mandible is large but does not extend very much below the lower border of the horizontal ramus. The masseteric fossa is deep.
C. B. Schultz and C. H. Falkenbach 1950SKULL: Larger than those of Hypsiops breviceps and H. luskensis, slightly larger than average examples of H. brachymelis petersoni, somewhat smaller and less massive than those of H. johndayensis; mesocephalic; nasals retracted anteriorly to area above anterior of P 1 ; anterior nasal-maxilla contact above P 2 ; posterior portion of arch somewhat U-shaped in outline from side view, with sharp rise of inferior border; posterior border of arch extending posteriorly to anterior border of postglenoid process; malar deep below orbit; infraorbital foramen above anterior border of P4•
MANDIBLE:Same size comparisons as in skull; postsymphysis below midline of Pa.
DENTITION:C/ large; /C approximately twice the size of Ia, spatulate shape in outline; premolars crowded (worn in holotype, but suggesting presence of anterior intermediate crest on P2 and P3) ; P3 with suggestion of posterior intermediate crest.
LIMBS: Slightly longer than known examples of other species of genus (H. johndayensis known from fragmentary examples only).
C. B. Schultz and C. H. Falkenbach 1950 (Hypsiops breviceps)SKULL: Smaller than examples of H. brachymelis, approximately same length but wider than H. luskensis; brachycephalic, more so than in other species of genus; supra-occipital wings (damaged in holotype, only known specimen) suggesting less posterior extension than in H. luskensis; anterior nasal-maxilla contact above middle of P2; infraorbital foramen above posterior portion of P8; deep lacrimal fossa
MANDIBLE: Similar to H. brachymelis, but of smaller size; postsymphysis below P3.
DENTITION: More hypsodont than in other species of genus; series almost as long as those of H. brachymelis; cheek teeth con- siderably heavier than in H. luskensis and similar to those of H. brachymelis; superior and inferior premolars crowded; PLP 8 each set at an angle to alveolar border; anterior intermediate crest on p1-paclose to externalborder of teeth; P1-Pa each set at an angle to alveloar border; Pa with posterior intermediate crest.
LIMBS: Similar to examples of H. luskensis; smaller than those of holotype of H. brachymelis.
M. S. Stevens et al. 2023Smaller species of Hypsiops (M1-3 length = 52-64 mm; P2-M3 = 89-109 mm; m1-3 = 60-68 mm; p2-m3 = 93-107 mm), with deep malar region, making the snout tall and narrow, and slight retraction of the narial notch