Metarhinus

Metarhinus
Temporal range: Middle Eocene (early–middle Uintan), 46.3–42.8 Ma
Metarhinus jaw at Mission Trails Regional Park visitor center
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Perissodactyla
Family: †Brontotheriidae
Genus: †Metarhinus
Osborn, 1908
Type species
Metarhinus fluviatilis
Osborn, 1908
Species
  • M. abbotti (Riggs, 1912)
  • M. fluviatilis (Osborn, 1908)
  • M. pater (Stock, 1937)
Synonyms
  • Telmatherium accola (Cook, 1926)
  • Telmatherium advocata (Cook, 1926)
  • Metarhinus riparius (Riggs, 1912)
  • Metarhinus cristatus (Riggs, 1912)
  • Metarhinus earlei (Riggs, 1912)
  • Heterotitanops parvus (Peterson, 1914)

Metarhinus is a genus of brontothere endemic to North America. It lived during the Eocene, in the early and middle Uintan land mammal age.

Description

In terms of dentition, Metarhinus had rather primitive morphology. The genus bears enlarged canines and diagonal premolars. The molars of adult specimens are deeply worn, and the skull has an elongated and high sagittal crest. In both jaws there is a short post-canine diastema. Different species of Metarhinus have unique nasal mophologies, with M. fluvialtilis having spoon-shaped nasals and M. diploconus having tapered nasals. This unique anatomical trait has been suggested to indicate that Metarhinus had an advanced sense of smell.

Classification

Like other basal brontotheres, Metarhinus has a very rocky taxonomic history. The validity of species assigned to Metarhinus is often debated, with species formerly assigned to Metarhinus often being moved to related genera or being grouped within other Metarhinus species.

References

  1. 1 2 Hodnett, John-Paul M.; Welsh, Edward T.; Santucci, Vincent L.; Tweet, Justin S. (2022). "A Middle Eocene brontothere (Mammalia; Perissodactyla; Brontotheriidae) from Yellowstone National Park, Wyoming". FOSSIL RECORD 8. New Mexico Museum of Natural History and Science. p. 211.
  2. ↑ 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.
  3. 1 2 Mihlbachler, Matthew C.; Deméré, Thomas A. (2010-07-14). "Phylogenetic status of Metarhinus pater (Brontotheriidae: Perissodactyla) from Southern California and species variation in Metarhinus from the middle Eocene of North America". Journal of Vertebrate Paleontology. 30 (4): 1229–1244. doi:10.1080/02724634.2010.483568. ISSN 0272-4634.
  4. 1 2 Field Museum of Natural History.; History, Field Museum of Natural (1912). Publication. Field Museum of Natural History. Geological series. Vol. v.4:no.2 (1912). Chicago, U.S.A: The Museum.
  5. ↑ Mader, Bryn J. (2009-12-12). "The cranial anatomy of Metarhinus (Mammalia, Perissodactyla, Brontotheriidae)". Journal of Vertebrate Paleontology. 29 (4): 1300–1305. doi:10.1671/039.029.0429. ISSN 0272-4634.
  6. 1 2 3 College~bmader@qcc.cuny.edu, Bryn J. Mader~Queensborough Community (2019-02-12). "The narial morphology of Metarhinus and Sphenocoelus (Mammalia, Perissodactyla, Brontotheriidae)". Palaeontologia Electronica. Retrieved 2025-11-08.
  7. ↑ "Metarhinus undetermined - Plazi TreatmentBank". publication.plazi.org. Retrieved 2025-11-08.
  8. ↑ Mader, Bryn J. (2008-07-30). "A species level revision of Bridgerian and Uintan brontotheres (Mammalia, Perissodactyla) exclusive of Palaeosyops". Zootaxa. 1837 (1): 1–85. doi:10.11646/zootaxa.1837.1.1. ISSN 1175-5334.