Yuichiro Nishioka

New Data on the Neogene Anthracotheres (Mammalia, Artiodactyla) from Central Myanmar

ABSTRACT 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.

New Hystrix (Mammalia, Rodentia) from the late Miocene/early Pliocene of Myanmar

YUICHIRO NISHIOKA,*,1 ZIN-MAUNG-MAUNG-THEIN,2 NAOKO EGI,1 TAKEHISA TSUBAMOTO,3 TAKESHI NISHIMURA,1 TSUYOSHI ITO,1 THAUNG-HTIKE,4 and MASANARU TAKAI1; 1Primate Research Institute, Kyoto University, Inuyama 484-8506, Japan, nishioka@pri.kyoto-u.ac.jp; 2Mandalay University, 73rd Road, Mandalay, Myanmar; 3Center for Paleobiological Research, Hayashibara Biochemical Laboratories, Inc, Okayama 700-0907, Japan; 4Shwebo Degree College, Shwebo, Myanmar

Late Pliocene rodents from the Irrawaddy sediments of central Myanmar and their palaeogeographical significance

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

X-Ray Computed Tomography Examination of a Fossil Beaver Tooth from the Lower Miocene Koura Formation of Western Japan

Abstract. We describe the tooth of a fossil beaver (Castoridae, Rodentia) discovered in the lower Miocene Koura Formation of Shimane Prefecture, western Japan. The specimen is an isolated, unworn left lower third molar that can be assigned to a large castorid, Youngofiber. To determine the taxonomic classification based on the internal enamel patterns of the tooth, we reconstructed those patterns using a three-dimensional image by X-ray peripheral quantitative computed tomography (pQCT). The obtained enamel patterns indicate that the M3 of Youngofiber is characterized by a transversely elongated proparafossettid and simple synclinids running obliquely and parallel. Moreover, the present specimen retains a well developed mesostriid extending up to half the lingual height of the crown. This characteristic is shared with another castorid specimen from the lower Miocene Nojima Group in Nagasaki Prefecture, suggesting a close relationship between Koura and Nojima beavers.

Small mammalian remains from the late holocene deposits on Ishigaki and Yonaguni Islands, Southwestern Japan

Yuichiro Nishioka, Ryohei Nakagawa, Shin Nunami, and Satoshi Hirasawa (2016) Small mammalian remains were newly discovered from the Late Quaternary sediments of the Yaeyama region (Ishigaki and Yonaguni Islands) in the southwestern-most part of Japan. We examined these materials based on taxonomical and chronological approaches, in order to reconstruct the past fauna in this region. Accelerator Mass Spectrometry radiocarbon dating indicates that the mammalian assemblages from Ishigaki and Yonaguni Islands are composed mainly of late Holocene fossils. The fossil assemblage from Ishigaki Island comprises five species of small mammals belonging to Soricomorpha (Suncus murinus), Chiroptera (Pteropus sp., Hipposideros turpis, and Rhinolophus perditus), and Rodentia (Niviventer sp.). One rodent bone, collected from the fissure sediments near Sabichi-do Cave, Ishigaki Island, is dated at 230 ± 20 yBP (ca. AD 1,700), and is considered part of the recent remain. Furthermore, the fossil assemblage from Umabana-zaki Fissure, on Yonaguni Island, is dated at 1,760 ± 20 yBP (ca. AD 300) and comprises three species of small mammals belonging to Chiroptera (Pipistrellus cf. abramus) and Rodentia (Niviventer sp. and Mus musculus). Niviventer is not currently distributed in Japan. Only domestic rats (Rattus rattus and R. norvegicus) live on Ishigaki and Yonaguni Islands at the present time. However, the fossil assemblage from Umabana-zaki Fissure is dominated completely by Niviventer sp. Most fossils of small mammals found from the late Holocene Ishigaki and Yonaguni Islands represented species that are currently endemic to the Yaeyama region. Niviventer sp. from these islands is unique because this form has never been found from neighboring regions, such as Taiwan and Miyako Islands, and because it likely existed in the late Holocene. These discoveries support the hypothesis that the Yaeyama region had been isolated zoogeographically from the continent even during the Last Glacial Maximum, when the sea level had drastically fallen.

Late Pliocene Semnopithecus fossils from central Myanmar: rethinking of the evolutionary history of cercopithecid monkeys in Southeast Asia

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.

First discovery of colobine fossils from the Late Miocene/Early Pliocene in central Myanmar.

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 (M(1)?) 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.

A night heron (Ciconiiformes, Ardeidae) and a stork (Ciconiidae) from the Pliocene of Myanmar (Burma)

Two new avian specimens from the Pliocene part of the Irrawaddy sediments of central Myanmar represent the youngest known fossil records of birds from Myanmar (Burma) that previously was restricted to one specimen of an ibis from the middle Eocene. The age of the Sulegon-1 fossil locality is likely from the later part of the Pliocene based on the presence of the suid Sivachoerus prior, the anthracotheriid Merycopotamus dissimilis, and the Sumatran rhinoceros Dicerorhinus sp. cf. D. sumatrensis. The distal tarsometatarsus is from a night heron (Ardeidae: Nycticoracini) and exhibits derived (and primitive) features consistent with night herons, but not other groups of ardeids, including the absence of a lateral deflection of trochlea III and a trochlear furrow extending to the proximal plantar end of trochlea III. The night heron fossil is not distinguishable from some species of Gorsachius and Nycticorax and may derive from one of the extant species in Southeast Asia. The other specimen (a distal tibiotarsus) represents a taxon of stork (Ciconiidae: cf. Leptoptilini) and displays many characters associated with that group (incuding a large centrally positioned intercondylar tubercle, a rounded intercondylar fossa, and distally notched trochlear rims). This stork is smaller than the ‘giant’ storks known from the Plio-Pleistocene of Asia and Africa, and may represent a relative of one of the large extant Asian storks. The inferred paleohabitat of the Sulegon locality as a tidal deltaic habitat is consistent with the lifestyle of both the extant night herons and large storks that occur in southeastern Asia today. Thomas A. Stidham. Key Laboratory for Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China. presbyornis@gmail.com Takehisa Tsubamoto. Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime Prefecture 790-8577, Japan. tsubamoto@sci.ehime-u.ac.jp Zin-Maung-Maung-Thein. Department of Geology, Magway University, Magway, Magway Region, Myanmar. zmmtgeo@gmail.com Thaung-Htike. Department of Geology, University of Mandalay, Mandalay, Mandalay Region, Myanmar. thaunghtikejp@gmail.com Naoko Egi. Primate Research Institute, Kyoto University, Inuyama, Aichi Prefecture 484-8506, Japan. egi.naoko.6z@kyoto-u.ac.jp Stidham, Thomas A., Tsubamoto, Takehisa, Zin-Maung-Maung-Thein, Thaung-Htike, Egi, Naoko, Nishioka, Yuichiro, Maung-Maung, and Takai, Masanaru. 2016. A night heron (Ciconiiformes, Ardeidae) and a stork (Ciconiidae) from the Pliocene of Myanmar (Burma). Palaeontologia Electronica 19.2.36A: 1-12 palaeo-electronica.org/content/2016/1597-pliocene-birds-from-myanmar Copyright:

Geographic Variation of Absolute and Relative Lower Molar Sizes in the Japanese Macaque (Macaca fuscata: Primates, Mammalia)

We examined geographic variations of absolute and relative lower molar sizes (size proportions among M1, M2, and M3) in the Japanese macaque (Macaca fuscata) using skull specimens obtained from 13 locations. We compared the geographic patterns and climatic factors. The size of M1 significantly and negatively correlated to the annual and coldest month mean temperatures and precipitation for both males and females. The M2/M1 and M3/M1 scores significantly and positively correlated to the annual and coldest month mean temperatures. The geographic pattern in the size of M1 was consistent with Bergmanns rule; however, the sizes of M2 and M3 did not correlate with temperature, and were not consistent with the rule. The geographic pattern in relative molar sizes (M2/M1 and M3/M1 scores) indicated that populations living in colder climates possess a larger M1 in relation to M2 and M3. Therefore, the correlations of M1, M2/M1, and M3/M1 scores to temperature involve an increase in the size of M1 in a colder climate. In macaques, the functions of the different molars (M1, M2, and M3) do not differ (they all exhibit grinding function, unlike differentiation between carnassial and other molars in Carnivora), whereas the timing of molar eruption does. In other words, at young ages (1.5–3.5 years), M1 erupts and is in occlusion, whereas M2 and M3 do not erupt and are not used for mastication. Therefore, the geographic pattern in the relative molar sizes may be attributed to increasing survivability in harsh winter climates by increasing occlusal surface in younger animals.

Taxonomic examination of longgu (Fossilia Ossis Mastodi, “dragon bone”) and a related crude drug, longchi (Dens Draconis, “dragon tooth”), from Japanese and Chinese crude drug markets

Longgu (“dragon bone,” Ryu-kotsu, Fossilia Ossis Mastodi, or Os Draconis) is the only fossil crude drug listed in the Japanese Pharmacopoeia. All longgu in the current Japanese market is imported from China, where its resources are being depleted. Therefore, effective countermeasures are urgently needed to prevent resource depletion. One possible solution is the development of a substitute made from bones of contemporary animals that are closely related to the original animal source of the current longgu. However, no research has been conducted on the original animal source of longgu, except for a report on the longgu specimens present in the Shosoin Repository. Taxonomic examination was performed on the fossil specimens related to longgu which are owned by the Museum of Osaka University, Japan. In total, 20,939 fossil fragments were examined, of which 20,886 were mammalian fossils, and 246 of these fossils were classified into nine families. The longgu specimens from the Japanese market belonged to a relatively smaller variety of taxa than those from the Chinese market. Despite the variety of taxa in longgu, medical doctors using Kampo preparations with longgu have not reported any problems due to the presence of impurities in the original animal source. These results suggest that the effect of longgu is independent of its origin as long as it is closely related to the origin of the current longgu. Thus, despite the considerable effects of fossilization, our results could help in developing an optimal substitute for longgu.