|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Mammalia - Perissodactyla - Brontotheriidae
It was recombined as Rhadinorhinus diploconum by Riggs (1912), Osborn (1929) and Mader (1989); it was recombined as Fossendorhinus diploconus by Mihlbachler (2008); it was recombined as Metarhinus diploconus by Osborn (1908), Mader (1998) and Mader (2008).
|Year||Name and author|
|1895||Telmatotherium diploconum Osborn p. 85 fig. 6|
|1908||Metarhinus diploconus Osborn|
|1912||Rhadinorhinus abbotti Riggs|
|1912||Rhadinorhinus diploconum Riggs|
|1912||Rhadinorhinus abbotti Riggs p. 36|
|1929||Rhadinorhinus diploconum Osborn|
|1989||Rhadinorhinus diploconum Mader|
|1998||Metarhinus diploconus Mader|
|2008||Metarhinus diploconus Mader p. 8|
|2008||Fossendorhinus diploconus Mihlbachler|
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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.
|H. F. Osborn 1895||Superior premolar-molar series,174mm. A large hypocone upon last upper molar. Naso-frontals without horn. Long sagittal crest. Canines small, rounded.|
|M. C. Mihlbachler 2008||Fossendorhinus diploconus is an intermediate-sized hornless brontothere. The nasal incision extends posteriorly as far back as the anterior margin of the M1. The orbits are positioned above the M2 and protrude laterally, though not to the degree seen in Metarhinus. The premaxilla is robust and does not contact the nasal bone. The premaxillomaxillary rostral cavity is open dorsally and there are two large fossae inside the nasal chamber. The premaxillomaxillary rostrum is strongly upturned and is relatively constant in thickness throughout its length. Other cranial features include a well-devel- oped sagittal crest, a strongly concave mid- cranial dorsal surface, a strongly convex posterior dorsal surface, thin and strongly curved zygomatic arches, and a ventrally open and mediolaterally directed external auditory pseudomeatus.
Dentally, Fossendorhinus diploconus has three large upper incisors, a distinct P2 metacone, weak premolar preprotocristae, short lingual crests extending posteriorly from the premolar protocones, and small hypocones on P2 and P3. 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 and an anterolingual cingular cusp are absent. Cen- tral molar fossae are present. All traces of molar paraconules and metalophs are lost.
Fossendorhinus diploconus is most similar to Metarhinus, but can be clearly differenti- ated from Metarhinus by the autapomorphic fossae inside the nasal chamber, the less laterally protruding orbits, and the more strongly upturned rostrum.