チュウブ ニホン ノ クワジマソウ テトリ ソウグン オヨビ トウホク チュウゴク ノ サカイソウ フシンソウ ヨリ サンシュツシタ ゼンキ ハクアキ タコウトウルイ ノ ヨサツテキ キサイ ト タコウトウルイ ノ シンカシ

京都大学0048新制・課程博士博士(理学)甲第12118号理博第3012号新制||理||1449(附属図書館)23954UT51-2006-J113京都大学大学院理学研究科地球惑星科学専攻(主査)教授 瀬戸口 烈司, 教授 増田 富士雄, 教授 平島 崇男学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDA

A clue to the Neocomian vertebrate fauna : initial results from the Kuwajima "Kaseki-kabe" (Tetori Group) in Shiramine, Ishikawa, central Japan

More than 30 vertebrate species have been collected from the Kuwajima "Kaseki-kabe" (fossilbluff), an outcrop of the Lower Cretaceous Kuwajima Formation (Tetori Group), in Shiramine Village, Ishikawa Prefecture. This means the site is one of the most fertile Early Cretaceous fossil localities in the world. The diversity includes four fishes, one frog, tritylodontids, three turtles, probably three pterosaurs, seven dinosaurs, seven lizards, one choristodere, one bird and two mammals. In this paper, the vertebrate assemblage of the "Kaseki-kabe" is documented to reaffirm its significance

Stratigraphy of the late Mesozoic Tetori Group in the Hakusan Region, central Japan : an overview

The late Mesozoic Tetori Group is distributed in central Japan. Although the stratigraphy of this Group is thought to be quite important to study the fossil assemblage including various vertebrate remains collected from the Group, it is rather complicated. We review in the present paper the geological studies on the Tetori Group around Mt. Hakusan to give accurate information especially on the stratigraphy of this Group. The Tetori Group consists of the Kuzuryu, Itoshiro and Akaiwa subgroups in ascending order. The formations compose these subgroups in the reviewed districts are as follows. Kuzuryu River district, Fukui Prefecture Kuzuryu Subgroup. Shimoyama, Oidani, Tochimochiyama, Kaizara and Yambarazaka formations. Itoshiro Subgroup. Yambara, Ashidani, Obuchi and Itsuki formations. Akaiwa Subgroup. Akaiwa and Kitadani formations. Tedori River district, Ishikawa Prefecture Itoshiro Subgroup. Gomijima and Kuwajima formations. Akaiwa Subgroup. Akaiwa and Myodani formations. Shokawa district, Gifu Prefecture Kuzuryu Subgroup. Ushimaru, Akahoke and Mitarai formations. Itoshiro Subgroup. Otaniyama, Okurodani and Amagodani formations. Akaiwa Subgroup. Okura and Bessandani formations. Following formations are thought to be almost the same horizon: the upper part of the Kaizara Formation and the lower part of the Mitarai Formation; the Kuwajima, Itsuki and Okurodani formations; the lower part of the Akaiwa Formation along the Tedori and Kuzuryu rivers and the Okura Formation. Only five formations are correlated to the geologic time units based on the index fossils: the Kaizara (Bathonian to Oxfordian), Yambarazaka (Oxfordian), Mitarai (Callovian to ?Tithonian), Kitadani and Myodani (upper Barremian to lower Aptian) formations. To summarize, the Kuzuryu, Itoshiro and Akaiwa subgroups in these districts are roughly correlated to the Middle to Upper Jurassic, Upper Jurassic to lower Lower Cretaceous and Lower Cretaceous, respectively. The formations from which vertebrate remains have been collected are: the Otaniyama, Itsuki, Kuwajima, Okurodani and Amagodani formations of the Itoshiro Subgroup, and the Akaiwa and Kitadani formations of the Akaiwa Subgroup

Early Cretaceous eutriconodontans and multituberculates (Mammalia) from the Shahai and Fuxin formations, northeastern China

Kusuhashi Nao, Hu Yaoming, Wang Yuanqing. Early Cretaceous eutriconodontans and multituberculates (Mammalia) from the Shahai and Fuxin formations, northeastern China. In: Documents des Laboratoires de Géologie, Lyon, n°164, 2008. Mid-Mesozoic life and environments. Cognac (France), June 24th-28th 2008. pp. 52-55

Isolated dinosaur teeth from the Lower Cretaceous Shahai and Fuxin formations of northeastern China

International audienceIsolated dinosaur teeth recovered from seven localities near Fuxin (western Liaoning Province, northeastern China) are described. They come from sediments belonging to the Shahai and Fuxin formations, considered to be Aptian to Albian in age. Seven taxa have been recognized. They include the oviraptorosaur Incisivosaurus, dromaeosaurid theropods, Euhelopus-like sauropods, as well as indeterminate nodosaurid, ankylosaurid, iguanodontoid and basal neoceratopsian ornithischians. The Shahai and Fuxin dinosaur faunas show the persistence of some Jehol biota taxa such as the highly specialised Incisivosaurus, basal titanosauriform sauropods, basal neoceratopsians and some dromaeosaurids, and the addition of more derived iguanodontoids and ankylosaurians. The persistence of some dinosaurs of the Jehol Biota into the Shahai and Fuxin formations suggests a long term stability of Liaoning terrestrial environments during the Early Cretaceous. Despite sampling bias and the rather small sample that must be taken into account, teeth abundances show a significant compositional difference between the localities of the Shahai and Fuxin formations, neoceratopsian teeth representing one third of dinosaur tooth remains in the Shahai Formation whereas they are totally absent in the Fuxin Formation. Ankylosaur teeth, in contrast, represent 3% of total remains in the Shahai Formation, whereas they seem to be the only herbivorous dinosaurs in the Fuxin Formation with 40% of the total number of teeth (the rest being theropod dinosaur teeth). Although a difference in micro-environmental conditions between Shahai and Fuxin localities may at least partly explain such pattern, the unusual and unbalanced faunal composition of Fuxin localities remains enigmatic and will need further field collecting in order to be clarified

reappraisalofendotheriumniinomiishikama1947aeutherianmammalfromthelowercretaceousfuxinformationfuxinjinzhoubasinliaoningchina

根据正型标本的印痕和翻制的模型,重新研究了产于辽宁阜新新邱阜新组的早白垩世真兽类哺乳动物新带氏远藤兽(Endotherium niinomii Shikama,1947)。对照Shikama(1947)的原始描述,将E.niinomii的主要特征归纳为:下臼齿从m1到m3逐渐变小;下三角座和下跟座的高差不是很大;下臼齿的齿尖钝;下原尖比下前尖和下后尖大,并且下前尖和下后尖高度相近;可能有5个前臼齿,并且p3不明显变小。这些特征组合足以将该属与其他的白垩纪真兽类相区别,因此认为Endotherium niinomii是一个有效种

reappraisalofendotheriumniinomiishikama1947aeutherianmammalfromthelowercretaceousfuxinformationfuxinjinzhoubasinliaoningchina

根据正型标本的印痕和翻制的模型,重新研究了产于辽宁阜新新邱阜新组的早白垩世真兽类哺乳动物新带氏远藤兽(Endotherium niinomii Shikama,1947)。对照Shikama(1947)的原始描述,将E.niinomii的主要特征归纳为:下臼齿从m1到m3逐渐变小;下三角座和下跟座的高差不是很大;下臼齿的齿尖钝;下原尖比下前尖和下后尖大,并且下前尖和下后尖高度相近;可能有5个前臼齿,并且p3不明显变小。这些特征组合足以将该属与其他的白垩纪真兽类相区别,因此认为Endotherium niinomii是一个有效种

Petrogenesis of isotopically enriched Quaternary magma with adakitic affinity associated with subduction of old lithosphere beneath central Myanmar

ミャンマーの活火山のマグマ生成メカニズムを解明 --今後も噴火する可能性の高い活火山であることが判明--. 京都大学プレスリリース. 2022-03-10.We present a model for the petrogenesis of magma with adakitic affinity in an old subduction zone, which does not involve slab melting and is constrained by new geochronological and geochemical data for Mt. Popa, the largest of three Quaternary volcanoes in central Myanmar (Popa, Monywa and Singu). The edifice is composed of Popa Plateau (0.8–0.6 Ma) with high-K rocks and a stratovolcano ( 40). The distinct K contents indicate that the adakitic magmas cannot be derived from Popa high-K rocks, but they share trace-element signatures and Sr–Nd isotope ratios with medium-K basalts from Monywa volcano. Our estimation of water contents in Popa magma reveals that primary magma for medium-K basalts was generated by partial melting of wedge mantle with normal potential temperature (TP 1330–1340 °C) under wet conditions (H₂O 0.25–0.54 wt%). Its melting was probably induced by asthenospheric upwelling that is recognized by tomographic images. Mafic adakitic magma (Mg# ~ 63, Sr/Y ~ 64) was derived from the medium-K basaltic magma in fractional crystallization of a garnet-bearing assemblage at high pressure, and felsic adakitic rocks (Mg# ~ 45, Sr/Y ~ 50) were produced by assimilation-fractional crystallization processes at mid-crustal depths

Taxonomic overview of Neogene crocodylians in Myanmar

Although Neogene crocodylians were well documented from Indo-Pakistan, few fossils were known from Southeast Asia, precluding the understanding of their evolutionary and biogeographic history. Here, we describe crocodylians from the Neogene Irrawaddy Formation of central Myanmar and evaluate their taxonomic status. Tebingan, SE of Magway (lower Upper Miocene) yields Gavialis and Crocodylus that differ from the previously known species of each genus, and the Gwebin area, SW of Bagan (Upper Pliocene) produces Crocodylus cf. palaeindicus. Taking into account the materials without provenance data, Neogene crocodylians from Myanmar include at least three gavialids and two Crocodylus that are characterized by different craniomandibular and postcranial features. The body length estimates for the gavialines from Tebingan and an unknown locality in central Myanmar are 7.5 m and 8.6 m, respectively, which exceed the maximum size limit of extant Gavialis gangeticus. Together with the previously reported large taxa, gavialids repeatedly evolved large body sizes in the Neogene of Asia. Gavialis from the Miocene of Myanmar is one of the oldest records of the genus, and its unraised orbital rim suggests that the “telescoped” eyes derived later during the genus evolution. Crocodylus cf. palaeindicus from the Pliocene of Myanmar indicates the species range was extended from western India to Myanmar during the Neogene. The absence of Crocodylus siamensis in the Neogene of India and central Myanmar implies the species originated east of central Myanmar

Preliminary Investigation of Seasonal Patterns Recorded in the Oxygen Isotope Compositions of Theropod Dinosaur Tooth Enamel

Oxygen isotope compositions of tooth enamel increments in theropod dinosaurs are investigated as potential proxies of climate seasonality. Six teeth of large carnivorous theropods collected from four Cretaceous formations deposited under contrasted climates have been sampled. These teeth have been analyzed for the oxygen isotope compositions of their apatite phosphate (δ18Op) through incremental sampling performed along the major growth axis. Significant fluctuations in oxygen isotope compositions along the growth axis of each tooth are observed and interpreted as reflecting seasonality in ingested local surface water δ18Ow values. Fluctuations in δ18Op values of theropod teeth from the Aptian of Thailand and Cenomanian of Morocco vary similarly to meteoric water δ18Omw values occurring today in sub-tropical regions subjected to large seasonal amounts of precipitations. A dinosaur tooth recovered from the more inland and mid-latitude Nemegt Formation of Mongolia shows a seasonal pattern similar to present-day cold temperate and continental climate. Finally, the high latitude and coastal Kakanaut Formation (Russia) experienced strongly dampened seasonal variations, most likely due to the influence of warm Pacific oceanic currents. Such conditions occur today in high latitude regions submitted to marine influence. These results further highlight the potential of using the oxygen isotope compositions of large theropod teeth to reconstruct past seasonal variations of terrestrial climates. Increased knowledge of past seasonality may help to better understand the complex interactions between climate and the dynamics of land biodiversity in terms of ecological adaptations, biogeography and the evolutionary history of organisms