Dolichorhinus
Dolichorhinus is an extinct genus of brontothere, known from the Middle Eocene of North America. Several species have been named historically, but only one species is recognized as valid today, D. hyognathus.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. The nasal morphology of Dolichorhinus suggests it had an enhanced sense of smell. 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.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. Dolichorhinus itself has been considered a synonym of the related Sphenocoelus by some authors, though most recent literature disputes this.