Magway, Myanmar
Magway, Myanmar

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Amiri Roudan M.,University of Malaya | Ramesh S.,University of Malaya | Niakan A.,University of Kota | Wong Y.H.,University of Malaya | And 5 more authors.
Journal of Ceramic Processing Research | Year: 2017

In the present work, hydroxyapatite (HA) derived from calcined eggshell via a wet chemical precipitation method was investigated. The as-received eggshells was calcined at 900°C to produce crystalline calcium oxide which reacted with orthophosphoric acid under controlled conditions. The final solution was filtered, dried and sieved to obtain ready to press, phase pure hydroxyapatite powder as confirmed by X-ray diffraction (XRD) analysis. Green samples were prepared and sintered in air at various temperatures ranging from 900°C to 1300°C at a ramp rate of 10°C per minute and 1 hr holding time. The sintered samples were evaluated in terms of HA phase stability, relative density, grain size, Vickers hardness and fracture toughness. The results showed that the HA phase remained stable even after sintering at 1300°C. In addition, the relative density, Vickers hardness and fracture toughness were found to increase rapidly between 900 to 1100°C and reached a plateau thereafter. A relatively density of 98.5%, high Vickers hardness of 5.9 GPa and fracture toughness of 1.09 MPam1/2 was achieved at 1250°C despite having a large grain size of 2.5 µm at this temperature. © 2017, Hanyang University. All rights reserved.


Nishioka Y.,Kyoto University | Takai M.,Kyoto University | Nishimura T.,Kyoto University | Htike T.,Shwebo University | And 6 more authors.
Journal of Systematic Palaeontology | Year: 2015

The Upper Pliocene Irrawaddy sediments in the Gwebin area of central Myanmar recently yielded a rodent assemblage that contains nine species belonging to four families: four species of Muridae, three of Hystricidae, one of Spalacidae, and one of Sciuridae. The murids consist of Hapalomys cf. longicaudatus, Maxomys pliosurifer sp. nov., Rattus jaegeri and cf. Rattus sp. indet., which include both extinct and extant forms. Maxomys pliosurifer is relatively similar to Maxomys surifer that lives in South-East Asia in terms of tooth morphology but retains plesiomorphic features shared with the ancestral rat, Karnimata, and possible sister genera of Maxomys, such as Ratchaburimys and Millardia. The three hystricids belong to the genus Hystrix and consist of two extinct brachydont species (Hystrix paukensis and Hystrix sp. indet.) and one hypsodont species similar to living form (Hystrix cf. brachyura). This finding indicates that primitive brachydont species and derived hypsodont species of Hystrix had likely coexisted in the locality, but the brachydont species are significantly more common amongst specimens collected from the Gwebin area. The spalacid species is Cannomys cf. badius and the sciurid species is Menetes sp. indet. These two rodents are similar to living species in continental South-East Asia although they show minor differences in tooth characteristics compared to the living forms. Some species and genera of the fossil rodent assemblage from the Gwebin area also occur in Upper Pliocene localities of Thailand, suggesting chronological correlation between these two faunas. Moreover, these fossil rodent assemblages are composed primarily of the species distributed endemically in continental South-East Asia. Late Pliocene rodents of continental South-East Asia were affected by river barriers that formed during the Mio-Pliocene, and they were probably not able to disperse from South-East Asia into South and East Asia. http://zoobank.org/urn:lsid:zoobank.org:pub:0171B3BE-02D4-433C-A5CE-4729C537FAF8. © 2014 The Trustees of the Natural History Museum, London 2014. All Rights Reserved.


Shimada K.,DePaul University | Shimada K.,Fort Hays State University | Egi N.,Kyoto University | Tsubamoto T.,Ehime University | And 6 more authors.
Zootaxa | Year: 2016

We redescribe an extinct river shark, Glyphis pagoda (Noetling), on the basis of 20 teeth newly collected from three dif-ferent Miocene localities in Myanmar. One locality is a nearshore marine deposit (Obogon Formation) whereas the other two localities represent terrestrial freshwater deposits (Irrawaddy sediments), suggesting that G. pagoda from the Irrawad-dy sediments was capable of tolerating low salinity like the extant Glyphis. Glyphis pagoda likely reached up to at least 185 cm in total body length and was probably piscivorous. The fossil species occurs in rocks of Myanmar and eastern and western India and stratigraphically ranges at least from the Lower Miocene (Aquitanian) to the lower Upper Miocene (mid-Tortonian). It has been classified under at least eight other genera to date, along with numerous taxonomic synonyms largely stemming from the lack of understanding of the heterodonty in extant Glyphis in the original description. Our lit-erature review suggests that known Miocene shark faunas, particularly those in India, are manifested with unreliable tax-onomic identifications and outdated classifications that warrant the need for a comprehensive taxonomic review in order to evaluate the evolutionary history and diversity pattern of Miocene shark faunas. The genus Glyphis has a roughly 23- million-year-long history, and its success may be related to the evolution of its low salinity tolerance. While extant Glyphis spp. are considered to be particularly vulnerable to habitat degradation and overfishing, the fossil record of G. pa-goda provides renewed perspective on the natural history of the genus that can be taken into further consideration for con-servation biology of the extant forms. © 2016 Magnolia Press.


PubMed | Mandalay University, Waseda University, Fukui Prefectural Dinosaur Museum, Fort Hays State University and 4 more.
Type: Journal Article | Journal: Zootaxa | Year: 2016

We redescribe an extinct river shark, Glyphis pagoda (Noetling), on the basis of 20 teeth newly collected from three different Miocene localities in Myanmar. One locality is a nearshore marine deposit (Obogon Formation) whereas the other two localities represent terrestrial freshwater deposits (Irrawaddy sediments), suggesting that G. pagoda from the Irrawaddy sediments was capable of tolerating low salinity like the extant Glyphis. Glyphis pagoda likely reached up to at least 185 cm in total body length and was probably piscivorous. The fossil species occurs in rocks of Myanmar and eastern and western India and stratigraphically ranges at least from the Lower Miocene (Aquitanian) to thelower Upper Miocene (mid-Tortonian). Ithas been classified under at least eight other genera to date, along with numerous taxonomic synonyms largely stemming from the lack of understanding of the heterodonty in extant Glyphis in the original description. Our literature review suggests that known Miocene shark faunas, particularly those in India, are manifested with unreliable taxonomic identifications and outdated classifications that warrant the need for a comprehensive taxonomic review in order to evaluate the evolutionary history and diversity pattern of Miocene shark faunas. The genus Glyphis has a roughly 23-million-year-long history, and its success may be related to the evolution of its low salinity tolerance. While extant Glyphisspp. are considered to be particularly vulnerable to habitat degradation and overfishing, the fossil record of G. pagoda provides renewed perspective on the natural history of the genus that can be taken into further consideration for conservation biology of the extant forms.


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.


Takai M.,Kyoto University | Nishioka Y.,Osaka University | Thaung-Htike,Shwebo University | Maung M.,Magway University | And 4 more authors.
Historical Biology | Year: 2016

We here describe a new fossil species of Asian colobine monkey, Semnopithecus gwebinensissp. nov. from the Late Pliocene Irrawaddy sediments of the Gwebin area in central Myanmar. Extant Semnopithecus (Hanuman langur) is a relatively large, terrestrial colobine monkey known as one of the most adaptable non-human primates. It is widely distributed, mainly in the Indian subcontinent, from Pakistan in the west to Bangladesh in the east. However, in Myanmar Semnopithecus is not distributed but Trachypihtecus is, which is the closest relative to Semnopithecus. It is presumed that extant Trachypithecus pileatus, which is considered to be a hybrid of Semnopithecus and Trachypithecus from molecular biological studies, appeared in the Early Pleistocene as the result of hybridisation between the two genera. On the other hand, no fossil specimens of other cercopithecid monkeys, such as Macaca, Trachypithecus or Rhinopithecus, all of which are commonly discovered from the Pleistocene cave sediments of South China, have been found from the Pliocene sediments in central Myanmar to date. The dissimilarity in the primate fauna between central Myanmar and South China suggests little faunal interchange between the two regions probably because of geographical barriers such as large rivers and high mountain ranges in the area. © 2016, © 2015 Taylor & Francis.


Takai M.,Kyoto University | Soe A.N.,Defence Service Academy | Maung M.,Magway University | Tsubamoto T.,Hayashibara Museum of Natural science | And 3 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.

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