Late Middle Pleistocene ecology and climate in Northeastern Thailand inferred from the stable isotope analysis of Khok Sung herbivore tooth enamel and the land mammal cenogram Kantapon Suraprasit a, b, * , Herv  e Bocherens c, d , Yaowalak Chaimanee b , Somsak Panha e , Jean-Jacques Jaeger b a Department of Geology, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand b PALEVOL, UMR CNRS 7262 INEE, Universit e de Poitiers, 6 rue Michel Brunet, 86022, Poitiers, France c Department of Geosciences, Biogeology, University of Tübingen, H€ olderlinstrasse 12, 72074, Tübingen, Germany d Senckenberg Research Centre for Human Evolution and Paleoenvironment, University of Tübingen, Sigwartstrasse 10, 72076, Tübingen, Germany e Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand article info Article history: Received 10 October 2017 Received in revised form 25 May 2018 Accepted 2 June 2018 Keywords: Large mammal Stable isotopes Paleodiet Paleohabitat Paleoclimatology Pleistocene Thailand Southeastern Asia abstract Paleoecological and paleoclimatic records based on the stable isotopes of mammalian tooth enamel are poorly known in mainland Southeast Asia during the Pleistocene. Khok Sung in Northeastern Thailand is a late Middle Pleistocene terrace deposit, tentatively dated either as 213 ka or 188 ka, yielding 15 described mammalian taxa with especially abundant and complete fossil remains. To investigate pale- odiets and habitats of these ancient mammals and to understand the corresponding regional climate, we performed an analysis of stable carbon and oxygen isotopes extracted from tooth enamel carbonate of various mammalian taxa, coupled with the cenogram method. The enamel d 13 C values of Khok Sung mammals indicate a variety of diets, ranging from pure C 3 to C 4 plants, suggesting that C 4 grasses were a major component of local Thai ecosystems during the late Middle Pleistocene. The stable isotopic distinction between C 3 and C 4 plants suggests that the Pleistocene wildlife habitats ranged from closed forests to open grasslands for the Khok Sung area. Moreover, differences within sympatric Pleistocene herbivores such as proboscideans, rhinoceroses, and cervids characterize possible niche partitioning by minimizing interspecific overlap. Paleoclimatic interpretations based on the intra-tooth variability in enamel d 18 O values from large mammals and on the cenogram analysis reflect significant seasonal variations in precipitation and temperature, and humid conditions, for the Khok Sung locality. Compared to modern environments in Thailand, it is apparent that C 4 -dominated grasslands were more widespread at that time when anthropic impacts on the ecosystems were presumably absent or minimal. © 2018 Published by Elsevier Ltd. 1. Introduction Southeast Asia is known today as one of the biodiversity hot- spots in the world, resulting from the complex interactions of its geological, biogeographical, and climatic events. In particular, changes in climate and sea levels in relation to repeated glacial cycles substantially impacted species diversification and faunal distribution in the region during the Pleistocene. A long history of paleontological excavations and research at numerous karstic sites with a few terrace deposits has provided essential data in relation to changes in faunal communities and suggests diverse paleo- habitat and paleoenvironmental conditions across mainland Southeast Asia throughout the Pleistocene glacial-interglacial cy- cles. Accordingly, our understanding of the terrestrial faunas and floras of the Pleistocene deposits has always played an important role in the reconstruction of these phenomena. However, the regional paleoclimate as indicated from the Pleistocene vegetation records remains questionable due to a scarcity of information from that period. Stable isotope analysis and serial sampling of tooth enamel of terrestrial fossil mammals constitutes a powerful tool for exploring several aspects of paleoecology, vegetation cover, * Corresponding author. Department of Geology, Faculty of Science, Chula- longkorn University, Bangkok, 10330, Thailand. E-mail addresses: Kantapon.S@chula.ac.th, suraprasit@gmail.com (K. Suraprasit). Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev https://doi.org/10.1016/j.quascirev.2018.06.004 0277-3791/© 2018 Published by Elsevier Ltd. Quaternary Science Reviews 193 (2018) 24e42