Dihoplus

Jaw fragment of the type species Dihoplus schleiermacheri

Species of Dihoplus were large rhinoceroses with two horns. The nasal septum was not ossified, with a nasal notch above the frontmost premolars. The toothrow is placed posteriorly within the skull. The first upper premolar is absent, though the lower second incisor is present.[1]

Members of Dihoplus were long placed in Dicerorhinus (which contains the living Sumatran rhinoceros). Sometimes these species are placed in the related Stephanorhinus. The genus is now generally considered distinct,[2] though there is still debate as to which species should be included; for example, Deng (2011) listed Merck's rhinoceros (Stephanorhinus kirchbergensis) under Dihoplus.[3] Species recently placed in the genus include:[4]

• D. schleiermacheri (Kaup, 1832) the type species of the genus, known from Late Miocene of Eppelsheim, Germany.[4]
• D. pikermiensis (Toula, 1906), known from the Late Miocene of Europe, originally placed in the genus Stephanorhinus.[4]
• ‘D.’ megarhinus (de Christol, 1834) known from the Late Miocene-Pliocene of Europe, Anatolia, China and Transbaikalia.[1][4] D. ringstoemi has been suggested to be a synonym of ‘D.’ megarhinus.[1] A study from 2021 suggested that this species should be placed in the genus Pliorhinus instead along with "Dicerorhinus" miguelcrusafonti from the Pliocene of Europe.[5][6]
• ‘D.’ bethlehemsis Pandolfi, Rivals and Rabinovich, 2023, known from Pliocene aged deposits from Bethlehem in the Levant.[4]

The monophyly of the genus has been questioned, with some studies suggesting that D. pikermiensis and ‘D.’ megarhinus are more closely related to Stephanorhinus and Coelodonta (which contains the woolly rhinoceros) than to the type species D. schleiermacheri.[6]

Morphological phylogeny after Pandolfi (2023), excluding living African rhinoceros species.[6]