Wednesday, February 29, 2012

[Palaeontology • 2011] Khoratpithecus ayeyarwadyensis • First Hominoid from the Late Miocene of the Irrawaddy Formation (Myanmar)

MFI-K171, holotype mandible of Khoratpithecus ayeyarwadyensis n. sp.

For over a century, a Neogene fossil mammal fauna has been known in the Irrawaddy Formation in central Myanmar. Unfortunately, the lack of accurately located fossiliferous sites and the absence of hominoid fossils have impeded paleontological studies. Here we describe the first hominoid found in Myanmar together with a Hipparion (s.l.) associated mammal fauna from Irrawaddy Formation deposits dated between 10.4 and 8.8 Ma by biochronology and magnetostratigraphy. This hominoid documents a new species of Khoratpithecus, increasing thereby the Miocene diversity of southern Asian hominoids. The composition of the associated fauna as well as stable isotope data on Hipparion (s.l.) indicate that it inhabited an evergreen forest in a C3-plant environment. Our results enlighten that late Miocene hominoids were more regionally diversified than other large mammals, pointing towards regionally-bounded evolution of the representatives of this group in Southeast Asia. The Irrawaddy Formation, with its extensive outcrops and long temporal range, has a great potential for improving our knowledge of hominoid evolution in Asia.

Systematic Paleontology Superfamily Hominoidea Gray 1825, Family Hominidae Gray 1825, Subfamily Ponginae Elliot 1913, Genus Khoratpithecus Chaimanee et al. 2004, Khoratpithecus ayeyarwadyensis sp. nov
Holotype. Left hemi-mandible with P3-M2 (MFI-K171, collection of the Paleontology Section of the Department of Mineral Resources (DMR), Bangkok – 10400, Rama VI Road, Thailand).

Figure 1. Location of the Khoratpithecus-bearing localities of Thailand and Myanmar.

J.-J. Jaeger, A. N. Soe, O. Chavasseau, P. Coster, E.-G. Emonet, F. Guy, R. Lebrun, A. A. Maung, H. Shwe, S. T. Tun, K. L. Oo, M. Rugbumrung, H. Bocherens, M. Benammi, K. Chaivanich, P. Tafforeau, and Y. Chaimanee. 2011. First Hominoid from the Late Miocene of the Irrawaddy Formation (Myanmar). PLoS ONE 6 (4): 1–14. doi:10.1371/journal.pone.0017065.