Shwebo, Myanmar
Shwebo, Myanmar

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Zaw K.,University of Tasmania | Meffre S.,University of Tasmania | Takai M.,Kyoto University | Suzuki H.,Otani University | And 7 more authors.
Gondwana Research | Year: 2014

The Late Middle Eocene Pondaung Formation, central Myanmar hosts the richest deposit of terrestrial mammals in SE Asia. The Pondaung Formation contains anthropoid primates, such as Eosimiidae, Amphipithecidae and the new Afrotarsiidae, plus adapiform primates and is a critical locality in discussions on anthropoid origins and biogeography. The sands of the Pondaung Formation were derived from the erosional unroofing of a dissected andesitic volcanic arc and deposited on the forested floodplains of a large tropical river. Previously, the age of the Pondaung Formation was estimated to be Middle to Late Eocene based on stratigraphic evidence, Late Middle Eocene (Bartonian) based on comparisons with mammals from North America and Europe, 37.2. ±. 1.3. Ma and 38.8. ±. 1.4. Ma based on fission track dating and 37.4-37.0. Ma based on questionable magnetostratigraphic correlations. Here, we report a new LA-ICP-MS, U-Pb age for zircons from a tuffaceous bed in the Pondaung Formation of 40.31. ±. 0.65. Ma and 40.22. ±. 0.86. Ma which is slightly older than the debatable magnetostratigraphic ages of 37-36. Ma and 38-39. Ma for the anthropoids from Egypt and Libya. Pending the acquisition of similarly reliable radiometric dates from all the North African and Asian sites, this new date provides support for an Asian origin for the anthropoids. Our new dates are close to the molecular clock date for the origin of the anthropoid primates and may provide a reliable calibration point for the molecular phylogenetic method. © 2013 International Association for Gondwana Research.

Egi N.,Kyoto University | Thaung-Htike,Shwebo Degree College | Zin-Maung-Maung-Thein,Mandalay University | Maung-Maung,Hinthada University | And 4 more authors.
Journal of Asian Earth Sciences | Year: 2011

A tooth of a mongoose (Mammalia: Carnivora: Herpestidae) was discovered from the Upper Irrawaddy sediments in central Myanmar. The age of the fauna is not older than the mid-Pliocene. It is identified as a right first upper molar of a small species of Urva (formally included in the genus Herpestes) based on its size and shape. The present specimen is the first carnivoran from the Upper Irrawaddy sediments and is the first record of mongooses in the Pliocene and early Pleistocene of Asia. It confirms that mongooses had already dispersed into Southeast Asia by the late Pliocene, being consistent with the previous molecular phylogenetic analyses. The fossil may belong to one of the extant species, but an assignment to a specific species is difficult due to the fragmentary nature of the specimen and the small interspecific differences in dental shape among the Asian mongooses. The size of the tooth suggests that the Irrawaddy specimen is within or close to the clade of Urva auropunctata+. javanica+. edwardsii, and this taxonomic assignment agrees with the geographical distribution. © 2011 Elsevier Ltd.

Ogino S.,Kyoto University | Egi N.,Kyoto University | Zin-Maung-Maung-Thein,Mandalay University | Thaung-Htike,Shwebo Degree College | Takai M.,Kyoto University
Journal of Asian Earth Sciences | Year: 2011

Here we describe a new species of giant short-faced fossil bears, Agriotherium myanmarensis sp. nov. (Ursidae, Carnivora), from the latest Miocene to early Pliocene Irrawaddy sediments in the Chaingzauk area, central Myanmar. A. myanmarensis has a short mandible and a deep premasseteric fossa, both of which are the typical feature of Agriotherium. There are two specimens discovered so far: in the type specimen the inferior border of the mandibular corpus is rectilinearly-shaped, the m1 talonid is rather reduced, m1 metaconid larger than the entoconid-entoconulid ridge, the diastema between canine and p4 is very short, and the postcanine teeth are so reduced that existing cheek teeth are very crowded. Agriotherium had been widely distributed from the late Miocene through Pleistocene in Europe, East Asia (China), North America, and South Africa, but no fossil record has been reported from Southeast Asia. Except its extreme short snout, A. myanmarensis is most similar to that of the European form, Agriotherium insigne, rather than to the Asian species from Siwalik or China, such as Agriotherium palaeindicus, Agriotherium sivalensis, and Agriotherium inexpetans, suggesting the phylogenetic closeness to the European rather than to the South/East Asian forms. © 2011.

Zin-Maung-Maung-Thein,Kyoto University | Zin-Maung-Maung-Thein,Mandalay University | Takai M.,Kyoto University | Tsubamoto T.,Hayashibara Biochemical Laboratories Inc. | And 5 more authors.
Journal of Asian Earth Sciences | Year: 2010

Four genera and one indeterminate genus (total eight species) of fossil rhinoceroses (Mammalia; Perissodactyla; Rhinocerotidae) are recognized from the Neogene of central Myanmar. In the early Miocene, most area of central Myanmar were under the shallow marine condition, and no rhinocerotid remain has been documented yet. During the middle to late Miocene, the rhinocerotid remains are commonly found and are represented by "Diceratherium" naricum, Brachypotherium perimense, Brachypotherium fatehjangense and an indeterminate rhinocerotid. In the latest Miocene, these archaic rhinoceroses became extinct. In the late Neogene, the extant genera, Rhinoceros (late Miocene to Pleistocene) and Dicerorhinus (Plio-Pleistocene) first appeared in Myanmar. They appear to have dispersed to the Island Southeast Asia from the continental Asia during the early Pleistocene to middle Pleistocene when the eustatic sea level became low remarkably. © 2009 Elsevier Ltd. All rights reserved.

Zin-Maung-Maung-Thein,Mandalay University | Takai M.,Kyoto University | Uno H.,University of Tokyo | Wynn J.G.,University of South Florida | And 7 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2011

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 δ13C values of porcupines, tragulids, rhinocerotids, suids and proboscideans show that these mammals preferentially consumed C3 plants in a wooded environment, whereas the δ13C 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. © 2010 Elsevier B.V.

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