Sphenocoelus

Sphenocoelus; Temporal range: Middle Eocene (early Uintan), 46.3–45.7 Ma PreꞒ Ꞓ O S D C P T J K Pg N Da. S T Ypr. Lut. B Pr. Rup. Ch.
	Skeletal reconstruction of Sphenocoelus sp.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Infraclass:	Placentalia
Order:	Perissodactyla
Family:	†Brontotheriidae
Genus:	†Sphenocoelus; Osborn, 1895
Species
	S. uintensis (Osborn, 1895);
Synonyms
	Dolichorhinoides;

Sphenocoelus is an extinct genus of brontothere known from North America during the Middle Eocene.

Description

Sphenocoelus is an average-sized brontothere, with a dolichocephalic skull.^[2]^[3] Some specimens of Sphenocoelus bear a prominent sagittal crests, though others lack them entirely.^[4] The molars are long and narrow, and the third and fourth premolars have a cusp on the posterior medial (central hind) portion of the tooth.^[2] They bear four digits on the forefeet.^[5]

Classification

Sphenocoelus has had a complicated classification history, with many genera being split off or lumped within the group at various times.^[4]^[5] Currently, Sphenocoelus is placed within Brontotheriidae.^[2]^[5]^[4] The genus Dolichorhinus was once considered a species of Sphenocoelus, S. hyognathus, but is now in its own genus.^[6]^[5]

References

↑ 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.
1 2 3 Granger, Walter; Gregory, William K (1943). "A revision of the Mongolian titanotheres". Bulletin of the AMNH. 80 10. New York: American Museum of Natural History: 363–364.
↑ Osborn, Henry Fairfield; Peterson, Olof August (1895). "Fossil mammals of the Uinta Basin : expedition of 1894". Bulletin of the AMNH. 7 2. New York: American Museum of Natural History: 98–102.
1 2 3 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. Bibcode:2008Zoot.18377.1.1M. doi:10.11646/zootaxa.1837.1.1. ISSN 1175-5334.
1 2 3 4 Mihlbachler, Matthew (2008). "Species Taxonomy, Phylogeny, and Biogeography of the Brontotheriidae (Mammalia: Perissodactyla)". Bulletin of the American Museum of Natural History. 501: 1. doi:10.1206/0003-0090(2008)501[1:stpabo]2.0.co;2.
↑ 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 2026-01-28.