Dolichorhinus

Dolichorhinus
Temporal range: Middle Eocene (Uintan),
Skeleton of D. hyognathus.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Perissodactyla
Family: Brontotheriidae
Subfamily: Brontotheriinae
Genus: Dolichorhinus
Hatcher, 1895
Species:
D. hyognathus
Binomial name
Dolichorhinus hyognathus
(Osborn, 1889)
Synonyms
Synonyms of D. hyognathus
  • Dolichorhinus cornutum (Osborn, 1895)
  • Dolichorhinus intermedius Osborn, 1908
  • Dolichorhinus heterodon Douglass, 1909
  • Dolichorhinus longiceps Douglass, 1909
  • Dolichorhinus superior (Riggs, 1912)
  • Dolichorhinus fluminalis Riggs, 1912

Dolichorhinus is an extinct genus of brontothere, known from the Middle Eocene (Uintan) of North America.[1] Several species have been named historically, but only one species is recognized as valid today, D. hyognathus.[1]

Description

The cranium of Dolichorhinus is flattened at the top, similar to Palaeosyops. Unlike Palaeosyops, however, Dolichorhinus had slender zygomata and was dolichocephalic. The tooth morphology of Dolichorhinus suggests it consumed small, hardy plants.[2] The nasal morphology of Dolichorhinus suggests it had an enhanced sense of smell.[3] Above the orbits, there is a small protuberance, and the skull lacks a noticeable sagittal crest. The upper incisors of Dolichorhinus are sub-caniniform, and there is a noticeable post-canine diastema.[4] Similar to the condition in horses, Dolichorhinus has a coossified radius and ulna, as well as a partially coossified tibia and fibula.[5]

Classification

Dolichorhinus is placed within the subfamily Brontotheriinae. Historically, many species have been assigned to Dolichorhinus, though many have been assigned to other genera or synonymized with D. hyognathus.[6] Dolichorhinus itself has been considered a synonym of the related Sphenocoelus by some authors, though most recent literature disputes this.[3][1]

References

  1. ^ a b c Mihlbachler, Matthew C. (2008). "Species Taxonomy, Phylogeny, and Biogeography of the Brontotheriidae (Mammalia: Perissodactyla)". Bulletin of the American Museum of Natural History. 501. doi:10.1206/0003-0090(2008)501[1:STPABO]2.0.CO;2.
  2. ^ Osborn, Henry Fairfield (1929). The titanotheres of ancient Wyoming, Dakota, and Nebraska. University of Connecticut Libraries. Washington [D.C.] : Dept. of the Interior, U.S. Geological Survey.
  3. ^ a b [email protected], Bryn J. Mader~Queensborough Community (2019-02-12). "The narial morphology of Metarhinus and Sphenocoelus (Mammalia, Perissodactyla, Brontotheriidae)". Palaeontologia Electronica. Retrieved 2026-01-28.
  4. ^ "Species Taxonomy, Phylogeny, and Biogeography of the Brontotheriidae (Mammalia: Perissodactyla)". Bulletin of the American Museum of Natural History. doi:10.1206/0003-0090(2008)501[1:STPABO]2.0.CO;2.full.
  5. ^ O A Peterson (1924). Osteology of Dolichorhinus longiceps Douglass, with a review of the species of Dolichorhinus in the order of their publication.
  6. ^ Osborn, Henry Fairfield; Granger, Walter. "Upper Eocene and Lower Oligocene titanotheres of Mongolia. American Museum novitates ; no. 202". digitallibrary.amnh.org. Retrieved 2026-01-28.