1. Paleontology Section, Geological Survey Division, Department of Mineral Resources, Bangkok -10400, Thailand
2. Palynologie et Paléoenvironnements, I.S.E.M., cc 061, Place Eugene Bataillon, 34095-Montpellier, France
3. Paleomagnetismo, Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, 04510 Mexico DF, Mexico
4. Paléontologie, I.S.E.M., cc 064, Université Montpellier II, Place Eugene Bataillon, 34095-Montpellier, France

Correspondence to: Jean-Jacques Jaeger⁴ Correspondence and requests for materials should be addressed to J.-J.J. (e-mail: Email: jaeger@isem.univ-montp2.fr).

Abstract

The origin of orangutans has long been debated. Sivapithecus is considered to be the closest ancestor of orangutans because of its facial–palatal similarities¹, but its dental characteristics² and postcranial skeleton^{2, 3} do not confirm this phylogenetic position. Here we report a new Middle Miocene hominoid, cf. Lufengpithecus chiangmuanensis n. sp. from northern Thailand. Its dental morphology relates it to the Pongo clade, which includes Lufengpithecus^{4, 5}, Sivapithecus², Gigantopithecus⁶, Ankarapithecus⁷ and possibly Griphopithecus⁸. Our new species displays striking dental resemblances with living orangutans and appears as a more likely candidate to represent an ancestor of this ape. In addition, it originates from the geographic area of Pleistocene orangutans. But surprisingly, the associated flora shows strong African affinities, demonstrating the existence of a temporary floral and faunal dispersal corridor between southeast Asia and Africa during the Middle Miocene, which may have played a critical role in hominoid dispersion.