Paleoenvironmental analysis of Chaingzauk mammalian fauna (late Neogene, Myanmar) using stable isotopes from tooth enamel and its implication to paleogeography

Zin-Maung-Maung-Thein, Masanaru Takai, Hikaru Uno, Jonathan G. Wynn, Naoko Egi, Takehisa Tsubamoto, Thaung-Htike, Aung-Naing-Soe, Takeshi Nishimura, Minoru Yoneda

The tooth enamel of a mammalian fauna from the uppermost Miocene/lower Pliocene Irrawaddy sediments at Chaingzauk, west-central Myanmar were analyzed using stable carbon and oxygen isotopes. The ŚÄ13C values of porcupines, tragulids, rhinocerotids, suids and proboscideans show that these mammals preferentially consumed C3 plants in a wooded environment, whereas the ŚÄ13C values of bovids and hippopotamids indicate that they were grassland-adapted grazers to mixed feeders. In contrast to the thorn scrub, grassland and shrubland vegetation of present-day central Myanmar, stable carbon isotope results of the Chaingzauk fauna suggest a presence of wooded environment in the Chaingzauk area at that time. Present-day arid conditions are likely to have been caused by the uplift of the Indo-Burman Ranges due to the Himalayan Orogeny during the late Miocene to Pliocene, resulting in a rainshadow effect in central Myanmar. Furthermore, southward marine regression due to the rapid influx of sediments from the Indo-Burman Ranges, Eastern Himalayan Ranges and Sino-Burman Ranges into the Central Myanmar Basin in the Miocene to Pliocene might have played an important role in the aridification of this region since the lower Pliocene.

Palaeogeography, Palaeoclimatology, Palaeoecology 300:11-22 (2011)

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