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Shwebo, Myanmar

Yamaguchi T.,Kochi University | Suzuki H.,Otani University | Soe A.-N.,Defence Services Academy | Htike T.,Shwebo University | And 2 more authors.
Zootaxa | Year: 2015

The ostracode genus Bicornucythere (Ostracoda, Crustacea) is abundant in modern-day eutrophic marine bays, and is widely distributed in estuaries and inner bays throughout East Asia, including in China, Korea, Japan, and the Russian Far East. The evolutionary history of Bicornucythere is poorly understood. Here, we report on a new species of Bicornucythere (Bicornucythere concentrica sp. nov.) from the upper Eocene Yaw Formation in the Central Myanmar Basin. The oldest previously known Bicornucythere taxon, Bicornucythere secedens, was reported from lower Miocene strata in India, although a molecular phylogeny suggests that the genus first appeared in the Late Cretaceous. Bicornucythere concentrica sp. nov. is at least 10.9 million years older than the earliest known B. secedens. The new species occurs with Ammonia subgranulosa, a benthic foraminifer, an association that is representative of brackish water conditions in modern Asian bays. Our findings indicate that extant genera have inhabited Asian bays since the late Eocene. The paleobiogeography of Bicornucythere indicates that the taxon was dispersed onto Indian coasts during the collision between the Indian and Eurasian plates. Copyright © 2015 Magnolia Press.

Tsubamoto T.,Hayashibara Museum of Natural science | Tsubamoto T.,Okayama University of Science | Egi N.,Kyoto University | Takai M.,Kyoto University | And 2 more authors.
Paleontological Research | Year: 2013

A new genus and species of small bunodont artiodactyl (Mammalia), Myanmarius chitseini, is established on the basis of molar specimens from the upper middle Eocene Pondaung Formation, Myanmar. The specimens consist of upper molars and one m3. The m3 is provisionally referred to this species. Myanmarius is characterized by a low crown, bunodont cusps, a wide crushing trigon basin, a large metaconule, a reduced paraconule, a protocone distinctly larger than the other main cusps, an obtuse angled and inverted V-shaped centrocrista, a mesiodistally oriented postprotocrista and premetacristule, a buccally shifted and almost mesiodistally oriented cristid obliqua, no hypocone, no styles, and no lingual separation into two (mesial and distal) lobes of the upper molars. Our cladistic analysis supports the raoellid affinity of Myanmarius, which is nested with Khirtharia. However, if the m3 is excluded from the hypodigm of Myanmarius, the cladistic analysis rather supports the suoid affinity of Myanmarius. Therefore, the phyletic position of Myanmarius is still unclear. © 2013 by the Palaeontological Society of Japan.

Tsubamoto T.,Hayashibara Biochemical Laboratories Inc. | Thaung-Htike,Shwebo University | Zin-Maung-Maung-Thein,Mandalay University | Egi N.,Kyoto University | And 3 more authors.
Journal of Vertebrate Paleontology | Year: 2012

Gnatho-dental specimens of the anthracotheres (Mammalia; Artiodactyla) from the four Neogene localities of central Myanmar are described. Four species of anthracotheres are recognized in the Neogene of central Myanmar: Microbunodon silistrensis and a small bothriodontine from the middle Miocene; and Microbunodon milaensis and Merycopotamus dissimilis from the latest Miocene to Pliocene. This discovery extends the temporal range of Microbunodon up to the Pliocene. The co-occurrence of forest-dwelling Microbunodon and grass-eating and semi-aquatic Me. dissimilis reinforces that central Myanmar was less arid and had a wider range of habitats than the northern Indian Subcontinent during the Pliocene. This implies the possibility that Pliocene Southeast Asia might have been a refugium for some late Miocene forest-dwelling ungulates. © 2012 by the Society of Vertebrate Paleontology.

Takai M.,Kyoto University | Thaung-Htike,Shwebo University | Zin-Maung-Maung-Thein,Mandalay University | Soe A.N.,Defence Service Academy | And 5 more authors.
Journal of Human Evolution | Year: 2015

Here we report two kinds of colobine fossils discovered from the latest Miocene/Early Pliocene Irrawaddy sediments of the Chaingzauk area, central Myanmar. A left mandibular corpus fragment preserving M1-3 is named as a new genus and species, Myanmarcolobus yawensis. Isolated upper (M1?) and lower (M2) molars are tentatively identified as Colobinae gen. et sp. indet. Although both forms are medium-sized colobines, they are quite different from each other in M2 morphology. The isolated teeth of the latter show typical colobine-type features, so it is difficult to identify their taxonomic position, whereas lower molars of Myanmarcolobus have unique features, such as a trapezoid-shaped long median lingual notch, a deeply concave median buccal cleft, a strongly developed mesiobuccal notch, and rather obliquely running transverse lophids. Compared with fossil and living Eurasian colobine genera, Myanmarcolobus is most similar in lower molar morphology to the Pliocene Dolichopithecus of Europe rather than to any Asian forms. In Dolichopithecus, however, the tooth size is much larger and the median lingual notch is mesiodistally much shorter than that of Myanmarcolobus. The discovery of Myanmarcolobus in central Myanmar is the oldest fossil record in Southeast Asia not only of colobine but also of cercopithecid monkeys and raises many questions regarding the evolutionary history of Asian colobine monkeys. © 2015 Elsevier Ltd.

Tsubamoto T.,Ehime University | Egi N.,Kyoto University | Takai M.,Kyoto University | Thaung-Htike,Shwebo University | Zin-Maung-Maung-Thein,Mandalay University
Historical Biology | Year: 2016

The relationship between talar size and body mass in extant primates is examined to provide the regression equations for estimating the body mass of extinct primate species based on the talar size. The results indicate that, among the linear talar dimensions, the whole talar size and the tibial trochlear size are good body mass estimators for primates. As an example, the regression equations presented here were applied to the body mass estimates of the fossil tali (NMMP-39 and NMMP-82) of the amphipithecid primates from the middle Eocene Pondaung Formation of Myanmar. Based on the estimated body masses determined by this study, NMMP-39 (estimated body mass: ca. 2.7 kg) should likely be assigned to Ganlea megacanina or Myanmarpithecus yarshensis, while NMMP-82 (estimated body mass: ca. 4.9 kg) should likely be assigned to ‘Amphipithecus’ mogaungensis or Pondaungia cotteri. © 2016, © 2014 Taylor & Francis.

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