Sphenocoelus

Sphenocoelus is an extinct genus of brontothere known from North America and Asia during the Middle Eocene.^[1]

Sphenocoelus Temporal range: Middle Eocene 46–42 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Skeletal reconstruction of Sphenocoelus sp.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Perissodactyla
Family:	†Brontotheriidae
Genus:	†Sphenocoelus Osborn, 1895
Species
S. hyognathus (Osborn, 1889) S. intermedius (Osborn, 1908) S. uintensis (Osborn, 1895)
Synonyms
Dolichorhinus Telmatherium vallidens Manteoceras vallidens Dolichorhinoides Mesatirhinus superior

Description

Life reconstruction of Sphenocoelus intermedius (Formerly Mesatirhinus superior) by Robert Bruce Horsfall

Sphenocoelus is an average-sized brontothere, with a dolichocephalic skull.^[2][3] The narials of Sphenocoelus have been compared to those of the genus Metarhinus, with the nasal cavity being incredibly large. Because of this, it has been proposed that Sphenocoelus had an excellent sense of smell.^[4] Some specimens of Sphenocoelus bear a prominent sagittal crests, though others lack them entirely.^[5] 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 4 digits on the forefeet.^[6]

Classification

Sphenocoelus has had a complicated classification history, with many genera being split off or lumped within the group at various times.^[5][6] Currently, Sphenocoelus is placed within Brontotheriidae.^[2][6][5]