Lower molar endostructure in Rudapithecus hungaricus (late Miocene, Hungary)

International audience; Rudapithecus is a hominid known from the 10 Ma site of Rudabánya, in Hungary, sharing features that are unique to the African ape and human clade. However, the taxonomic diversity within Rudapithecus and its phylogenetic relationships with other fossil and extant hominid taxa remain controversial. We used X-ray microtomographic imaging to characterize the endostructure of Rudapithecus lower molars and compared it with that of other European Miocene apes (Dryopithecus and Ouranopithecus), the South Asian Miocene ape Sivapithecus, and extant hominids. We assessed 3D tooth crown tissue proportions, enamel thickness distribution patterns and conducted geometric morphometric analyses of the enamel-dentine junction (EDJ). Rudapithecus has moderately thick enamel similar to Pongo, thicker than in Dryopithecus and extant African apes, but thinner than in Ouranopithecus and extant humans. The thickest enamel is found at the apex of the cusps, similar to Gorilla, while in the other extant hominids it is located more laterally along the cusps. In EDJ morphology the Miocene apes overlap with Pongo but not extant hominines. Among Miocene apes only, Rudapithecus, Dryopithecus and Ouranopithecus plot close to one another and are discriminated from Sivapithecus, consistent with previous analyses indicating that the European taxa form a clade. RUD 14 plots closest to Ouranopithecus and closer to Dryopithecus than to RUD 212. The difference between the two Rudabánya specimens is greater than the difference between Rudapithecus and Dryopithecus, which is consistent with previous observations suggesting the presence of more than one ape taxon at Rudabánya.