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Diplacodon emarginatus
Taxonomy
Diplacodon emarginatus was named by Hatcher (1895) ["emarginatus": assigned tentatively, with Protitanotherium suggested if a new genus name is called for]. Its type specimen is PU 11242, a skull, and it is a 3D body fossil. Its type locality is Kennedy's Hole, which is in an Uintan terrestrial horizon in the Uinta Formation of Utah.
It was recombined as Protitanotherium emarginatum by Peterson (1914), Osborn (1923), Osborn (1929), Peterson (1934), Mader (1989), Mader (2000), Mihlbachler (2008) and Mader (2008).
It was recombined as Protitanotherium emarginatum by Peterson (1914), Osborn (1923), Osborn (1929), Peterson (1934), Mader (1989), Mader (2000), Mihlbachler (2008) and Mader (2008).
Synonyms
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Synonymy list
| Year | Name and author |
|---|---|
| 1895 | Diplacodon emarginatus Hatcher pp. 1084-1087 |
| 1902 | Diplacodon emarginatus Hay p. 633 |
| 1908 | Protitanotherium superbum Osborn |
| 1914 | Protitanotherium emarginatum Peterson p. 31 |
| 1923 | Protitanotherium emarginatum Osborn p. 3 |
| 1923 | Protitanotherium superbum Osborn p. 3 |
| 1929 | Protitanotherium emarginatum Osborn p. 377 figs. Plates LXVni, LXIX; text figures 24, 29, 87, 112, 314-320, 374, 375, 408, 648, 649, 712 |
| 1934 | Protitanotherium emarginatum Peterson |
| 1977 | Sthenodectes australis Wilson |
| 1989 | Protitanotherium emarginatum Mader |
| 2000 | Protitanotherium emarginatum Mader |
| 2008 | Protitanotherium emarginatum Mader p. 8 |
| 2008 | Protitanotherium emarginatum Mihlbachler p. 157 |
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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.
†Diplacodon emarginatus Hatcher 1895
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| H. F. Osborn 1929 | Pi-ms 294 millimeters (estimated), pi with a small talonid; ii small, round-topped; is large, bluntly pointed ; ia much larger than is. Lower canine more erect, recurved, and abruptly swelling at the base. Postcanine diastema short (27 mm.) but relatively longer than in P. superbum. Lower premolars and molars more brachyodont, with sloping curves. | |
| M. C. Mihlbachler 2008 | Protitanotherium emarginatum is a large brontothere with small, elliptical frontonasal horns positioned low on the skull. The nasal incision is dorsoventrally shallow and extends as far back as the P4. The nasal process is nearly horizontal, unelevated, short and broad, with thickened sides, and with a thickened and imperfectly rounded distal edge with a distinct median notch. The lateral margins of the nasal process are not upturned. The orbits are positioned above M2. The premaxillomaxil- lary rostrum thickens posteriorly and it is not sealed by bone dorsally. Other cranial characteristics include a saddle-shaped crani- um, separate parasagittal ridges that strongly constrict the dorsal surface of the cranium posteriorly, nearly straight zygomatic arches, and tube-shaped and mediolaterally angled external auditory pseudomeati. The posterior narial canal does not extend past the foramen ovale and large ventral sphenoidal fossae are absent.
Dentally, Protitanotherium emarginatum has three intermediate-sized subglobular up- per incisors, and metacones on P1 and P2. Premolar hypocones are absent, although a short lingual crest can occasionally be seen extending from the protocones. The molars have tall lingually angled ectolophs with weak labial ribs, and thinned lingual ectoloph enamel with wedge-shaped paracones and metacones. A cingular parastyle shelf is absent. Central molar fossae are present, but anterolingual cingular cusps are absent. Paraconules and metalophs are absent. The lower dentition includes three intermediate- sized semispatulate incisors with an enlarged i2, a distinct postcanine diastema, a metaco- nid on p4 but not on p2 or p3, shallow molar basins, and a slender m3. Protitanotherium emarginatum most close- ly resembles Protitan grangeri and Protitan minor, but it can be most easily distinguished from these species by the smaller, less subcaniniform incisors and tube-shaped ex- ternal auditory pseudomeatus. Additionally, Protitanotherium emarginatum is distinct from Diplacodon elatus in its relatively smaller horns, dorsoventrally shallow nasal incision, less deeply saddle-shaped cranium, differently shaped nasal process, and less molarized premolars. |
Measurements
No measurements are available
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| Source: f = family, subc = subclass, c = class, subp = subphylum | |||||
| References: Mader 1998, Ji et al. 2002, Carroll 1988, Lillegraven 1979, Hendy et al. 2009 | |||||