MF研究者総覧

研究者データベース

詳細
researchmap個人ページ
Last Updated :2024/07/25

研究者情報

マスター

アカウント（マスター）

  • 氏名

    小林　快次(コバヤシ　ヨシツグ), コバヤシ　ヨシツグ

所属（マスター）

  • 総合博物館

所属（マスター）

  • 総合博物館

独自項目

syllabus

  • 2021, 大学院共通授業科目（一般科目）：自然科学・応用科学, Inter-Graduate School Classes(General Subject):Natural and Applied Sciences, 修士課程, 大学院共通科目, 地球生命史，　生物進化，　地球環境変化，　気候変動，　生物大量絶滅，　生物多様性，　古生物科学，　地質年代
  • 2021, 大学院共通授業科目（教育プログラム）：博物館学, Inter-Graduate School Classes(Educational Program):Museology, 修士課程, 大学院共通科目, 学術標本・資料、博物館、学芸員、アドバンストコース
  • 2021, 環境と人間, Environment and People, 学士課程, 全学教育, 博物館、標本、資料、展示、実証的教育・研究、地球科学、生物学、考古学、情報学、教育学
  • 2021, 古生物学, Paleontology and Plaleobiology, 学士課程, 理学部, 進化，生命化石、化石記録、生物間相互作用、古生態、生物多様性変動、古環境
  • 2021, 一般教育演習(ﾌﾚｯｼｭﾏﾝｾﾐﾅｰ), Freshman Seminar, 学士課程, 全学教育, キャンパス、植物、昆虫、建築、古生物、海藻、岩石・鉱物、考古
  • 2021, 歴史・文化モジュール特殊科目B, History-Culture Module Special Subjects B, 学士課程, 現代日本学プログラム課程, 博物館、展示、学芸員
  • 2021, 博物館展示論, Theory of Museum Exhibitions, 学士課程, 文学部, 博物館、展示、学芸員

researchmap

プロフィール情報

学位

  • Ph.D.（Southern Methodist University）

プロフィール情報

  • 姓

    小林, コバヤシ

  • 名

    快次, ヨシツグ

  • ID各種

    201501081886466779

対象リソース

業績リスト

研究キーワード

  • 国際情報交換   系統   化石   進化   形態機能   機能形態   

研究分野

  • 自然科学一般 / 地球生命科学

経歴

  • 2019年 - 現在 大阪大学 総合学術博物館 招聘教授
  • 2019年 - 現在 北海道大学 総合博物館 教授
  • 2013年 - 2019年 大阪大学 総合学術博物館 招聘准教授
  • 2009年 - 2019年 北海道大学 総合博物館 准教授
  • 2008年 - 2009年 北海道大学 総合博物館 助教
  • 2005年 - 2008年 北海道大学 総合博物館 助手

受賞

  • 2018年10月 北海道 北海道文化奨励賞
     
    受賞者: 小林快次
  • 2017年11月 北海道新聞文化賞 学術部門
     
    受賞者: 小林快次
  • 2015年06月 日本古生物学会 学術賞
     
    受賞者: 小林快次

論文

  • Masaya Iijima, Arata Momohara, Yoshitsugu Kobayashi, Shoji Hayashi, Tadahiro Ikeda, Hiroyuki Taruno, Katsunori Watanabe, Masahiro Tanimoto, Sora Furui
    Palaeogeography, Palaeoclimatology, Palaeoecology 496 346 - 360 2018年05月01日 [査読有り][通常論文]
     
    Crocodylians are ectothermic animals, and their past distribution has been greatly influenced by changing climate since their Cretaceous origin. The Pliocene-Pleistocene witnessed a contraction of the crocodylian latitudinal ranges due to rapid cooling with superimposed pronounced orbital-scale climate oscillations. However, a chronologically-continuous record of the geographically marginal populations of crocodylians is yet to be provided for this time interval, and crocodylian response to such climatic changes is poorly known. This study describes a partial crocodylian skeleton from the Middle Pleistocene of Osaka, Japan, diagnosed as Toyotamaphimeia cf. machikanensis, on the basis of character comparisons, including ontogenetic skull shape change, and consideration of the reconstruction error in the holotype of T. machikanensis. Pliocene-Pleistocene record of fossil crocodylians in the Kinki, Tokai, and Kanto districts of Japan extends from ~3.5 Ma to ~0.3 Ma. The paleotemperature estimates for the crocodylian-bearing horizons indicate that late Early–Middle Pleistocene crocodylians in the Kinki district of Japan were living near their lower thermal limit. During the glacial periods, they might have moved to the southern extremity of Japan or locally became extinct from Japan, while re-expanding their range after the end of glacial periods.
  • Hang-Jae Lee, Yuong-Nam Lee, Thomas L. Adams, Philip J. Currie, Yoshitsugu Kobayashi, Louis L. Jacobs, Eva B. Koppelhus
    Palaeogeography, Palaeoclimatology, Palaeoecology 494 160 - 167 2018年04月01日 [査読有り][通常論文]
     
    A theropod tracksite was discovered in the Nemegt Formation (Maastrichtian) at Bügiin Tsav, Mongolia by the Korea-Mongolia International Dinosaur Project in 2009. A total of 67 tracks (14 trackways [one didactylous, 13 tridactylous] and 12 isolated tracks) belonging to four ichnomorphotypes were mapped on a single horizon. This indicates at least four different theropod trackmakers lived in the same area at the same time. This tracksite consists of laminated gray mudstone-yellowish brown siltstone couplets interbedded with eolian yellowish brown sandstone deposited on a distal floodplain. Abundant footprints with V-shaped profiles (cross-section) within in the vertical section indicate that dinosaurs repeatedly walked across in this area. Before the discovery of the tracks, the site was illegally excavated by fossil poachers, a widespread problem in the Gobi Desert. During excavation of the track horizon, a clenched, inclined Gallimimus foot skeleton was found in the mudstone, extended down 20 cm below the track-bearing sandstone layer. The occurrence of tracks closely associated with body fossils is unusual and taphonomically intriguing. It is possible that the foot skeleton represents an animal that died in its tracks. However, the depth of the foot in mud is probably too shallow for the animal to have been mired. Sedimentological and taphonomic evidence also suggests that the pes of Gallimimus may have passed straight through the track-bearing sandstone layer. The inclined right pes indicates that the body lay on its left side on the substrate. During decomposition in the mud, all digits were flexed but the distal phalanges were stuck and anchored in the stiff lower mud. Consequently, as more proximal phalanges were able to accommodate flexing, they were pulled away and dislocated from the anchored distal phalanges. Subsequent trampling by dinosaurs in the track-bearing sandstone would have further distorted the underlying foot.
  • Tsogtbaatar Chinzorig, Yoshitsugu Kobayashi, Khishigjav Tsogtbaatar, Philip J. Currie, Ryuji Takasaki, Tomonori Tanaka, Masaya Iijima, Rinchen Barsbold
    Palaeogeography, Palaeoclimatology, Palaeoecology 494 91 - 100 2018年04月01日 [査読有り][通常論文]
     
    The Upper Cretaceous Nemegt Formation of Mongolia is rich in well-preserved dinosaurs and Ornithomimosauria is one of the most common taxa in the formation. Three ornithomimosaur taxa, Anserimimus planinychus, Deinocheirus mirificus, and Gallimimus bullatus, have been discovered from the formation so far. However, the recently discovered specimens suggest there is even greater morphological variation of ornithomimosaurs in the Nemegt Formation than are presently recognized. This study focuses on the structures of manual elements among Nemegt ornithomimosaurs and reveals their remarkable diversity. The manual structures of seven individuals, including aforementioned three known taxa and four new individuals, are morphologically distinct from each other. Numerical analyses on metacarpals, phalanges, and unguals also support high morphological diversity of the Nemegt ornithomimosaurs. The large diversity of manual morphology may be related to large variety of palaeoecological niches were prevailed in the Nemegt ecosystem.
  • Ariana Paulina-Carabajal, Yuong-Nam Lee, Yoshitsugu Kobayashi, Hang-Jae Lee, Philip J. Currie
    Palaeogeography, Palaeoclimatology, Palaeoecology 494 135 - 146 2018年04月01日 [査読有り][通常論文]
     
    Ankylosaur braincase and endocranial morphologies are poorly known. Furthermore, cranial endocasts have been described for fewer than ten taxa so far. The complete inner ear morphology is known for only three species – Euoplocephalus tutus, Kunbarrasaurus ieversi, and Pawpawsaurus campbelli. Here, the first cranial endocast morphologies are presented for the Mongolian Cretaceous ankylosaurids Talarurus plicatospineus and Tarchia teresae. The study of paleoneurological features of these Mongolian taxa adds novel anatomical information to both species allowing the first comparison with ankylosaurids from North America. The development of a cerebellar flocculus that leaves an impression on the vestibular eminence – floccular recess – is observed in Euoplocephalus, Talarurus and T. teresae. Because this structure hasn't been identified in any nodosaurid so far, its presence in ankylosaurid cranial endocasts may represent a possible synapomorphy with unknown paleobiological implications.
  • Judai Nakajima, Yoshitsugu Kobayashi, Tsogtbaatar Chinzorig, Tomonori Tanaka, Ryuji Takasaki, Khishigjav Tsogtbaatar, Philip J. Currie, Anthony R. Fiorillo
    Palaeogeography, Palaeoclimatology, Palaeoecology 494 147 - 159 2018年04月01日 [査読有り][通常論文]
     
    The Nemegt locality is one of the most famous dinosaur localities in Mongolia ever since the site was discovered in 1946. It yields abundant dinosaur skeletons however, little attention had been given to dinosaur footprints at the locality. The only Nemegt dinosaur footprint study focused on descriptions of the footprints, gave only a few taxonomic implications, and provided no comparison with other dinosaur tracksites. This study reports newly recorded dinosaur footprints (hadrosaurs, sauropods, and theropods) at the Nemegt locality during the Nemegt Educational Expedition of 2016. A single footprint-bearing horizon that extends several kilometres was examined within the Nemegt Formation to determine the ichno-taxonomic assemblage of the Nemegt dinosaurs. A significant difference was identified between taxonomic compositions based on skeletal remains and ichno-taxonomic compositions based on footprints. Although the vast majority of the skeletal elements collected in the area belong to theropods, the footprints suggest that the Nemegt locality was dominated by herbivorous dinosaurs. This suggests that the previously inferred Tarbosaurus dominant taxonomic composition at the Nemegt locality is a result of a preservational bias. The size distribution of the newly studied footprints suggest that the Nemegt hadrosaurs had an adult-dominant and multigenerational population structure. Comparisons with dinosaur tracksites at the Cantwell (Alaska, USA) and Tremp (Spain) formations show that the population structure and body sizes of the Nemegt hadrosaurs were similar to those of the high-latitude Cantwell hadrosaurs. It suggests that the Nemegt area was more open and had higher plant productivity than the Tremp area.
  • Nest substrate reflects incubation style in extant archosaurs with implications for dinosaur nesting habits.
    Tanaka, K, Zelenitsky, D, Therrien, F, Kobayashi, Y
    Scientific Reports 8 3170  2018年 [査読有り][通常論文]
  • Comparative limb propotions reveal differential locomotor morphofunctions of alligatoroids and crocodyloids.
    Iijima, M, Kubo, T, Kobayashi, Y
    Royal Society Open Science 5 171774  2018年 [査読有り][通常論文]
  • Darla K. Zelenitsky, Francois Therrien, Kohei Tanaka, Yoshitsugu Kobayashi, Christopher L. DeBuhr
    CRETACEOUS RESEARCH 74 181 - 187 2017年06月 [査読有り][通常論文]
     
    The North American fossil record of dinosaur eggshells for the Cretaceous is primarily restricted to formations of the middle (Albian-Cenomanian) and uppermost (Campanian-Maastrichtian) stages, with a large gap in the record for intermediate stages. Here we describe a dinosaur eggshell assemblage from a formation that represents an intermediate and poorly fossiliferous stage of the Upper Cretaceous, the Santonian Milk River Formation of southern Alberta, Canada. The Milk River eggshell assemblage contains five eggshell taxa: Continuoolithus, Porituberoolithus, Prismatoolithus, Spheroolithus, and Triprismatoolithus. These ootaxa are most similar to those reported from younger Campanian-Maastrichtian formations of the northern Western Interior than they are to ootaxa reported from older middle Cretaceous formations (i.e., predominantly Macroelongatoolithus). Characteristics of the Milk River ootaxa indicate that they are ascribable to at least one ornithopod and four small theropod species. The taxonomic affinity of the eggshell assemblage is consistent with the dinosaur fauna known based on isolated teeth and fragmentary skeletal remains from the formation, although most ornithischians and large theropods are not represented by eggshell. Relative to the Milk River Formation eggshell, similar oospecies occurring in younger Cretaceous deposits tend to be somewhat thicker, which may reflect an increase in body size of various dinosaur lineages during the Late Cretaceous. Crown Copyright (C) 2017 Published by Elsevier Ltd. All rights reserved.
  • The oldest Asian hesperornithiform from the Upper Cretaceous of Japan, and the phylogenetic reassessment of Hesperornithiformes.
    Tanaka, T, Kobayashi, Y, Kurihara, K, Fiorillo, A, Kano, M
    Journal of Systematic Palaeontology 1 - 21 2017年 [査読有り][通常論文]
  • First ornithomimid (Theropoda, Ornithomimosauria) from the Upper Cretaceous Djadokhta Formation of Togrogiin Shiree, Mongolia.
    Chinzorig, T, Kobayashi, Y, Tsogtbaatar, K, Currie, P, Watabe, M, Barsbold, R
    Scientific Reports 7 5835  2017年 [査読有り][通常論文]
  • High diversity of the Ganzhou Oviraptorid Fauna increased by a new “cassowary-like” crested species.
    L_, J, Li, G, Kundr_t, M, Lee, Y, Sun, Z, Kobayashi, Y, Shen, C, Teng, F, Liu, H
    Scientific Reports 7 6393  2017年 [査読有り][通常論文]
  • Reanalysis of the phylogenetic status of Nipponosaurus sachalinensis (Ornithopoda: Dinosauria) from the Late Cretaceous of Southern Sakhalin.
    Takasaki, R. Chiba, K, Kobayashi, Y, Currie, P, Fiorillo, A
    Historical Biology 1 - 18 2017年 [査読有り][通常論文]
  • Masaya Iijima, Keiichi Takahashi, Yoshitsugu Kobayashi
    JOURNAL OF ASIAN EARTH SCIENCES 124 94 - 101 2016年07月 [査読有り][通常論文]
     
    The late Cenozoic fossil record of alligators in East Asia is crucial in understanding the origin and past distribution of Asian alligators that are now represented by a single species, Alligator sinensis. This study reports a partial skeleton of A. sinensis from the Late Pliocene (approximately 3.0 Ma) of western Japan. This Japanese A. sinensis is large in size (>200 cm total length), comparable to the maximum size of extant individuals. It demonstrates the oldest record of A. sinensis and wider distribution of this species in the past. Tectonic and geographic history of East Asia suggests that alligators presumably dispersed into Japan before 25 Ma or after 10 Ma, yet finally were wiped out from Japan due to the semi-isolated condition of the Japanese island arc and the deteriorated climate during the Plio-Pleistocene. (C) 2016 Elsevier Ltd. All rights reserved.
  • Lawrence J. Flynn, Yuri Kimura, Yoshitsugu Kobayashi, Xiaoming Wang, Zhuding Qiu, Changzu Jin, Louis L. Jacobs, Alisa J. Winkler, Yingqi Zhang, Louis H. Taylor, Naoki Kohno
    HISTORICAL BIOLOGY 28 1-2 1 - 7 2016年02月 [査読有り][通常論文]
  • Kentaro Chiba, Anthony R. Fiorillo, Louis L. Jacobs, Yuri Kimura, Yoshitsugu Kobayashi, Naoki Kohno, Yosuke Nishida, Michael J. Polcyn, Kohei Tanaka
    HISTORICAL BIOLOGY 28 1-2 289 - 303 2016年02月 [査読有り][通常論文]
     
    Derived members of the enigmatic mammalian order Desmostylia have molars comprising appressed columns whose morphology does not render their function in feeding simple to discern. Here we describe a new genus and species, Ounalashkastylus tomidai, more derived than Cornwallius but less derived than Desmostylus and Vanderhoofius, which develop a hypertrophied medial eminence on the dentary ontogenetically. Tooth morphology, vaulted palate and the medial eminence, which can rise to the level of the occlusal surface of M-2, suggest that derived desmostylids clenched their teeth strongly while employing suction during feeding, most likely on marine and coastal plants.
  • Kentaro Chiba, Michael J. Ryan, Dennis R. Braman, David A. Eberth, Evan E. Scott, Caleb M. Brown, Yoshitsugu Kobayashi, David C. Evans
    PALAIOS 30 9 655 - 667 2015年09月 [査読有り][通常論文]
     
    The horned dinosaur Centrosaurus apertus from the Belly River Group (Campanian) is represented by multiple articulated skulls and skeletons, and is particularly notable for its occurrence in dozens of large-scale monodominant bonebeds, which have been found in the Dinosaur Park Formation across southern Alberta and Saskatchewan. Here we present a detailed taphonomic analysis of the first large-scale Centrosaurus apertus bonebed (McPheeters bonebed) from the Oldman Formation of southeastern Alberta. The McPheeters bonebed rivals the richest bonebeds in the Dinosaur Park Formation in terms of bone density and size, and the complete disarticulation of elements. The bonebed occurs in an overbank facies and is dominated by small bone clasts, suggesting that only low energy water current contributed to the formation of the bonebed before its final burial event. Patterns of taphonomic modification suggest that bones experienced little weathering, breakage, or scavenging. In turn, these conclusions are compatible with an overall interpretation of rapid burial in humid conditions after the disarticulation of elements. These taphonomic features are virtually identical to those seen in the well-documented bonebeds of this species in the Dinosaur Park Formation, which are interpreted to represent mass death events caused by seasonal tropical storms and associated large-scale flooding. Late Cretaceous dinosaur species typically have small geographic and stratigraphic ranges defined by the extent of single geological formations. The new bonebed extends the distribution of Centrosaurus apertus to the upper Oldman Formation, which is interpreted as more inland than the coastally influenced Dinosaur Park Formation, and suggests that mass death events related to seasonal tropical storms occurred over a broader geographic area and in a greater range of paleoenvironments than previously documented.
  • Junchang Lu, Hanyong Pu, Yoshitsugu Kobayashi, Li Xu, Huali Chang, Yuhua Shang, Di Liu, Yuong-Nam Lee, Martin Kundrat, Caizhi Shen
    SCIENTIFIC REPORTS 5 11490  2015年07月 [査読有り][通常論文]
     
    The Ganzhou area of Jiangxi Province, southern China is becoming one of the most productive oviraptorosaurian localities in the world. A new oviraptorid dinosaur was unearthed from the uppermost Upper Cretaceous Nanxiong Formation of Ganzhou area. It is characterized by an anterodorsally sloping occiput and quadrate (a feature shared with Citipati), a circular supratemporal fenestra that is much smaller than the lower temporal fenestra, and a dentary in which the dorsal margin above the external mandibular fenestra is strongly concave ventrally. The position of the anteroventral corner of the external naris in relation to the posterodorsal corner of the antorbital fenestra provides new insight into the craniofacial evolution of oviraptorosaurid dinosaurs. A phylogenetic analysis recovers the new taxon as closely related to the Mongolian Citipati. Six oviraptorid dinosaurs from the Nanxiong Formation (Ganzhou and Nanxiong) are distributed within three clades of the family. Each of the three clades from the Nanxiong Formation has close relatives in Inner Mongolia and Mongolia, and in both places each clade may have had a specific diet or occupied a different ecological niche. Oviraptorid dinosaurs were geographically widespread across Asia in the latest Cretaceous and were an important component of terrestrial ecosystems during this time.
  • Yuong-Nam Lee, Rinchen Barsbold, Philip J. Currie, Yoshitsugu Kobayashi, Hang-Jae Lee, Pascal Godefroit, Francois Escuillie, Tsogtbaatar Chinzorig
    NATURE 515 7526 257 - U231 2014年11月 [査読有り][通常論文]
     
    The holotype of Deinocheirus mirificus was collected by the 1965 Polish-Mongolian Palaeontological Expedition at Altan Uul III in the southern Gobi of Mongolia(1). Because the holotype consists mostly of giant forelimbs (2.4 min length) with scapulocoracoids(2), for almost 50 years Deinocheirus has remained one of the most mysterious dinosaurs. The mosaic of ornithomimosaur and nonornithomimosaur characters in the holotype has made it difficult to resolve the phylogenetic status of Deinocheirus(3,4). Here we describe two new specimens of Deinocheirus that were discovered in the Nemegt Formation of Altan Uul IV in 2006 and Bugiin Tsav in 2009. The Bugiin Tsav specimen (MPC-D100/127) includes a left forelimb clearly identifiable as Deinocheirus and is 6% longer than the holotype. The Altan Uul IV specimen(MPC-D100/128) is approximately 74% the size of MPC-D 100/127. Cladistic analysis indicates that Deinocheirus is the largest member of the Ornithomimosauria; however, it has many unique skeletal features unknown in other ornithomimosaurs, indicating that Deinocheirus was a heavily built, non-cursorial animal with an elongate snout, a deep jaw, tall neural spines, a pygostyle, a U-shaped furcula, an expanded pelvis for strong muscle attachments, a relatively short hind limb and broad-tipped pedal unguals. Ecomorphological features in the skull, more than a thousand gastroliths, and stomach contents (fish remains) suggest that Deinocheirus was a megaomnivore that lived in mesic environments.
  • Thomas M. Cullen, David C. Evans, Michael J. Ryan, Philip J. Currie, Yoshitsugu Kobayashi
    BMC EVOLUTIONARY BIOLOGY 14 231  2014年11月 [査読有り][通常論文]
     
    Background: Osteohistological examinations of fossil vertebrates have utilized a number of proxies, such as counts and spacing of lines of arrested growth (LAGs) and osteocyte lacunar densities (OLD), in order to make inferences related to skeletochronology and mass-specific growth rates. However, many of these studies rely on samplings of isolated bones from single individuals. These analyses do not take individual variation into account, and as a result may lead to misleading inferences of the physiology of extinct organisms. This study uses a multi-element, multi-individual sampling of ornithomimid dinosaurs to test the amount of individual variation in the aforementioned osteohistological indicators. Based on these results we also assess the conclusions of previous studies that tested paleohistological hypotheses using isolated elements. Results: LAG number was found to be consistent within the hind limb bones of each individual, with the exception of the fibula, which preserves one additional LAG. Considerable differences in LAG spacing were found between elements of the sampled individuals, with larger variation found in elements of the foot compared with the femur, fibula, and tibia. Osteocyte lacunar density ranged between 29000 and 42000 osteocyte lacunae per mm(3), and was found to vary more between hind limb bones of an individual and within bones, than between the average values of individuals. Conclusions: The variation between hind limb elements in LAG number and LAG spacing suggests that direct comparisons of these elements may be misleading, and that LAG spacing is not a reliable proxy for mass-specific growth rates of an individual. Sampling of multiple bones should be performed as an internal check of model-based LAG retro-calculation and growth equations. The observation that osteocyte lacunar density varies more between individual bone elements than between average individual values suggests that the choice of sampled element can greatly influence the result, and care should be taken to not bias interpretations of the physiology of fossil tetrapods.
  • Anthony R. Fiorillo, Stephen T. Hasiotis, Yoshitsugu Kobayashi
    GEOLOGY 42 8 719 - 722 2014年08月 [査読有り][通常論文]
     
    The discovery of a new tracksite of mostly hadrosaurid dinosaur footprints, made by a herd living in an ancient high-latitude continental ecosystem, provides insight into the herd structure and behavior of northern polar dinosaurs and perspective on populations of large-bodied herbivores in an Arctic greenhouse world. This tracksite occurs in the Upper Cretaceous Cantwell Formation in the Alaska Range (Denali National Park, Alaska, United States), and it is the largest tracksite known from this far north. Preservation of the tracksite is exceptional: most tracks, regardless of size, contain skin impressions and they co-occur with well-preserved plant fossils and invertebrate trace fossils of terrestrial and aquatic insects. Statistical analyses of the tracks show that individuals of four different age classes of hadrosaurids lived together in a large social group. Our research results independently corroborate the growth curve for hadrosaurids proposed by paleohistologists that suggests that these dinosaurs experienced a period of rapid growth early in their life history.
  • Theropod tracks from the Lower Cantwell Formation (Upper Cretaceous) of Denali National Park, Alaska, USA with comments on theropod diversity in an ancient, high-latitude terrestrial ecosystem.
    Fiorillo, A. R, Contessi, M, Kobayashi, Y
    Bulletin of New Mexico Museum of Natural History and Science 429 - 439 2014年 [査読有り][通常論文]
  • Post-natal parental care in a Cretaceous diapsid from northeastern China.
    L_, J, Kobayashi, Y, Deeming, D. C, Liu, Y
    Geosciences Journal 1 - 8 2014年 [査読有り][通常論文]
  • Pterosaur tracks from the Lower Cantwell Formation (Campanian-Maastrichtian) of Denali National Park, Alaska, USA, with comments about landscape heterogeneity and habit preferences.
    Fiorillo, A. R, Kobayashi, Y, McCarthy, P. J, Wright, T. C, Tomsich, C., S
    Historical Biology 1 - 12 2014年 [査読有り][通常論文]
  • Iijima, M, Kobayashi, Y
    Paleobiology 40 608 - 624 2014年 [査読有り][通常論文]
  • Hanyong Pu, Yoshitsugu Kobayashi, Junchang Lü, Li Xu, Yanhua Wu, Huali Chang, Jiming Zhang, Songhai Jia
    PLoS ONE 8 5 e63423  2013年05月29日 [査読有り][通常論文]
     
    Therizinosauria are an unusual group of theropod dinosaurs, found mostly in the Cretaceous deposits in Mongolia, China and western USA. The basal forms of this group are represented by incomplete or disarticulated material. Here, we report a nearly complete, articulated skeleton of a new basal therizinosaur from the Early Cretaceous Yixian Formation of Jianchang County, western part of Liaoning Province, which sheds light on our understanding of anatomy of basal therizinosaurs. This new dinosaur shows some typical therizinosaur features, such as neural spines of the anterior caudal vertebrae that possess anterior and posterior alae, a rectangular buttress on the ventrolateral side of the proximal end of metacarpal I, and appressed metatarsal shafts. Our phylogenetic analysis suggests that it is a basal therizinosaur (sister taxon to Therizinosauroidea) because it bears many basal therizinosaur characters in the dentition, pelvis and hind limbs. The new therizinosaur described here has unique tooth and jaw characters such as the offsetting of the tooth row by a shelf and dentary teeth with labially concave and lingually convex dentary teeth, similar to ornithopods and ceratopsians. © 2013 Pu et al.
  • Thomas M. Cullen, Michael J. Ryan, Claudia Schroeder-Adams, Philip J. Currie, Yoshitsugu Kobayashi
    PLOS ONE 8 3 e58853  2013年03月 [査読有り][通常論文]
     
    Bonebeds can provide a wealth of anatomical, taphonomic, and ontogenetic information about the specimens preserved within them, and can provide evidence for inferred behavior. The material described here represents the first known bonebed of ornithomimids in North America, and the fourth record of an ornithomimosaur bonebed in the world. Partial skeletons representing three individuals are preserved in this assemblage, each comprising primarily portions of the posterior postcrania (pelvis, hind limbs and tail). All three individuals are morphologically similar, although one is larger in overall size. Given the stratigraphic position of the site, and the morphology of the postcrania, the preserved material represents a taxon from the clade containing Ornithomimus and Struthiomimus. Pedal ungual morphology is examined and found to be too variable to be useful in distinguishing these species taxonomically. This site provides additional evidence of gregarious behavior in ornithomimids and the first probable record of that behavior in North American forms.
  • Anthony R. Fiorillo, Thomas L. Adams, Yoshitsugu Kobayashi
    CRETACEOUS RESEARCH 37 291 - 299 2012年10月 [査読有り][通常論文]
     
    An unnamed nonmarine sedimentary package of rocks in southeastern Alaska in Wrangell-St. Elias National Park and Preserve has provided the first evidence of dinosaurs for this vast region. The rock unit is contained within the Wrangellia Terrane and exposures are of limited geographic extent. The rock unit is considered to be latest Cretaceous age. Sections are overwhelmingly dominated by extraformational conglomerates. Fine- to medium-grained light coloured sandstones are common and medium grey shales occur as minor components of the sections. Megafloral specimens indicate an abundance of horsetails, ferns and gymnosperm wood. Rather than two-dimensional impressions, most ferns are preserved in three dimensions, suggesting rapid burial. The abundance of charcoal in these rocks suggests that this area during deposition was also prone to ecological disturbance. Field parties found evidence of a small theropod and ornithopods. A single theropod pes impression is approximately 9 cm long and 7 cm wide. Attribution to the Theropoda was based on the sinusoidal shape of the impression of the middle digit. An ornithopod impression, identified by clearly blunt and rounded digit impressions, is approximately 22 cm long and 26 cm wide. All impressions are under tracks. (C) 2012 Elsevier Ltd. All rights reserved.
  • Darla K. Zelenitsky, Francois Therrien, Gregory M. Erickson, Christopher L. DeBuhr, Yoshitsugu Kobayashi, David A. Eberth, Frank Hadfield
    SCIENCE 338 6106 510 - 514 2012年10月 [査読有り][通常論文]
     
    Previously described feathered dinosaurs reveal a fascinating record of feather evolution, although substantial phylogenetic gaps remain. Here we report the occurrence of feathers in ornithomimosaurs, a clade of non-maniraptoran theropods for which fossilized feathers were previously unknown. The Ornithomimus specimens, recovered from Upper Cretaceous deposits of Alberta, Canada, provide new insights into dinosaur plumage and the origin of the avian wing. Individuals from different growth stages reveal the presence of a filamentous feather covering throughout life and winglike structures on the forelimbs of adults. The appearance of winglike structures in older animals indicates that they may have evolved in association with reproductive behaviors. These specimens show that primordial wings originated earlier than previously thought, among non-maniraptoran theropods.
  • Kohei Tanaka, Lu Junchang, Liu Yi, Huang Zhiqing, Yoshitsugu Kobayashi, Huang Dong, Darla K. Zelenitsky
    ACTA GEOLOGICA SINICA-ENGLISH EDITION 86 2 294 - 303 2012年04月 [査読有り][通常論文]
     
    The Zhutian and Dafeng formations (Upper Cretaceous) of the Heyuan Basin in northeastern Guangdong Province, China, have produced thousands of dinosaur eggs. Macromorphological features (egg diameter, egg shape, outer surface texture, and shell thickness) of 461 eggs were analyzed using non-destructive techniques and subjected to statistical analyses in order to assess their diversity and taxonomic affinities. Three types (1, 2 and 3) of eggs were discerned based on shape and outer surface morphology. Type 1 eggs are spherical to ellipsoidal in shape and have a rough surface. Three subtypes (Type 1-A-1, 1-A-2, and 1-B) are apparent from scatter plots and cluster analyses of egg diameters and shell thickness. Type 2 eggs are elongate with linear ornamentation on the surface, and are comparable to eggs that belong to the oofamily Elongatoolithidae. Type 3 eggs are elongate with a smooth surface, and are assigned to the oofamily Prismatoolithidae. Macromorphological features of the various egg types suggest that Type 1 could have been laid by ornithischian, sauropod or therizinosaur dinosaurs, Type 2 by oviraptorids, and Type 3 by troodontids. This study represents the first comprehensive statistical analysis of macrofeatures of dinosaur eggs, and reveals taxonomic diversity in the dinosaurs that were laying eggs in the Upper Cretaceous Heyuan area heretofore unrecognized in skeletal remains.
  • Li Xu, Yoshitsugu Kobayashi, Junchang Lue, Yuong-Nam Lee, Yongqing Liu, Kohei Tanaka, Xingliao Zhang, Songhai Jia, Jiming Zhang
    CRETACEOUS RESEARCH 32 2 213 - 222 2011年04月 [査読有り][通常論文]
     
    A partial skeleton of the ornithomimid dinosaur, discovered from the Late Cretaceous Qiupa Formation of Luanchuan County, Tantou Basin, Henan Province, China, is described here and assigned to a new genus and species, Qiupalong henanensis, with unique features (a notch on the lateral surface of the lateral posterior process of the proximal end of tibia and a small pit at the contact between astragalus and calcaneum). A phylogenetic analysis in this study suggests that it is a derived ornithomimid and form a monophyly with North American ornithomimids (Struthiomimus altus and Ornithomimus edmontonicus), sharing two characters (straight pubic shaft and large acute angle between pubic shaft and boot). Some characters (small anterior process of the pubic boot and curved pedal unguals) are seen in basal ornithomimosaurs as well, but these features in Q. henanensis are reversal. Qiupalong is the first definitive ornithomimid from outside of the Gobi Desert and is the southern-most occurrence of Late Cretaceous ornithomimid from eastern Asia, demonstrating southern extension of ornithomimid distribution in Asia. (C) 2010 Elsevier Ltd. All rights reserved.
  • Redescription of Saichania chulsanensis (Ornithischia, Ankylosauridae) from the Upper Cretaceous of Mongolia.
    Carpenter, K, Hayashi, S, Kobayashi, Y, Maryanska, T, Barsobold, R, Sato, K, Obata, I
    Palaeontographica Abteilung A-Palaozoologie-Stratigraphie 1 1 - 61 2011年 [査読有り][通常論文]
  • CT reconstruction and relationships of the Early Cretaceous tribosphenidan mammal, Slaughteria eruptens (Trinity Groups, Texas, USA).
    Winkler, D. A, Jacobs, L. L, Kobayashi, Y, Polcyn, M
    Palaeontologia Electronica 14 1 - 13 2011年 [査読有り][通常論文]
  • Kohei Tanaka, Lue Junchang, Yoshitsugu Kobayashi, Darla K. Zelenitsky, Xu Li, Jia Songhai, Qin Shuang, Tang Min'an
    ACTA GEOLOGICA SINICA-ENGLISH EDITION 85 1 66 - 74 2011年 [査読有り][通常論文]
     
    Here, we examine 145 dinosaur eggshells from a new fossil locality in the Qiupa Formation (Upper Cretaceous) of the Luanchuan area in western Henan Province, China. The eggshells display elongatoolithid macro- and microstructures, including ridges and nodes on the outer surface, two ultrastructural layers, and an undulatory boundary between the mammillary and continuous layers. A phylogenic analysis shows that the Luanchuan eggshells belong to the ooclade Elongatoolithidae. Within Elongatoolithidae, the thickness ratio of the mammillary layer to the entire eggshell, and the porosity of the Luanchuan eggshells are comparable to the oogenera Macroolithus and Elongatoolithus. There is no direct evidence for the taxonomic identity of the Luanchuan eggshells; however, they were likely laid by oviraptorids based on their phylogenetic position and their similarities with known oviraptorid eggs.
  • Anthony R. Fiorillo, Stephen T. Hasiotis, Yoshitsugu Kobayashi, Brent H. Breithaupt, Paul J. McCarthy
    JOURNAL OF SYSTEMATIC PALAEONTOLOGY 9 1 33 - 49 2011年 [査読有り][通常論文]
     
    The Upper Cretaceous Cantwell Formation in Denali National Park and Preserve (DENA), Alaska, contains an unparalleled fossil avian biodiversity. The Cantwell Formation, thousands of metres thick, was deposited near its current latitude and is exposed throughout much of DENA and elsewhere in the central Alaska Range. The Formation comprises a lower, dominantly fluvial sedimentary unit and an upper, mostly volcanic unit. Sedimentation of the lower unit was mainly in alluvial fan, braided and meandering stream, and lacustrine environments, with possible marginal-marine influence at times. Pollen data suggest that these sedimentary rocks are late Campanian or early Maastrichtian in age; thus the Cantwell Formation is correlative with other well-known dinosaur localities in Alaska. Bird tracks are preserved in multiple locations along a 40-km transect in DENA in fluvial and lacustrine deposits. Some bird tracks are found in association with dinosaur tracks and others are found on beds interbedded with dinosaur track-bearing layers. The approximate body sizes of the birds based on tracks show a range from sparrow- to heron-sized birds (25-30% larger than the modern Sandhill Crane Grus canadensis). The Cantwell Formation contains footprints assigned to several ichnotaxa found in either Asia or North America based on such morphological criteria as the presence or absence of a hallux, print size and shape, and angle of divarication: Aquatilavipes swiboldae, Ignotornis mcconnelli, Magnoavipes denaliensis sp. nov., Gruipeda vegrandiunus sp. nov. and Uhangrichnus chuni. The presence of a mixed Asian and North American ichnofauna suggests that at least some birds used Alaska as a bridge between Asia and North America. This diverse assemblage of avian traces, combined with the known fossil bone record and invertebrate trace fossil record, demonstrates that the northern Late Cretaceous polar region contained significant biodiversity.
  • Yuong-Nam Lee, Michael J. Ryan, Yoshitsugu Kobayashi
    NATURWISSENSCHAFTEN 98 1 39 - 49 2011年01月 [査読有り][通常論文]
     
    In 2008, a new basal neoceratopsian was discovered in the Tando beds (Albian) of Tando Basin in South Korea. It represents the first ceratopsian dinosaur in the Korean peninsula and is assigned to Koreaceratops hwaseongensis gen. et sp. nov. Autapomorphies of Koreaceratops include very tall neural spines over five times higher than the associated centra in the distal caudals, and a unique astragalus divided into two fossae by a prominent craniocaudal ridge on the proximal surface. A phylogenetic analysis indicates that Koreaceratops is positioned between Archaeoceratops and all more derived neoceratopsians, and the elongation of caudal neural spines was an important derived character in non-ceratopsid neoceratopsians. The very tall caudal neural spines in Koreaceratops, Montanoceratops, Udanoceratops, Protoceratops, and Bagaceratops appear to be homoplasious, suggesting an independent adaptation, possibly for swimming. Skeletal evidence suggests that obligate quadrupedalism occurred gradually in neoceratopsians progressing from bipedal through facultative quadrupedalism, to complete quadrupedalism in Coronosauria.
  • Hirayama, R, Kobayashi, Y, Sonoda, T, Sasaki, K
    Journal of Fossil Research 42 2 74 - 82 化石研究会 2010年 [査読有り][通常論文]
  • Lue Junchang, Yoshitsugu Kobayashi, Li Tianguang, Zhong Shimin
    ACTA GEOLOGICA SINICA-ENGLISH EDITION 84 6 1336 - 1342 2010年 [査読有り][通常論文]
     
    A new dinosaur Chuxiongosaurus lufengensis gen. et sp. nov. is erected based on a nearly complete skull. The taxon is characterized by the lacrimal perpendicular to the ventral margin of the upper jaw, which is similar to that of Thecodontosaurus; a depression present on the dorsal profile of the snout behind the naris; the rostral profile of the maxilla slopes continuously towards the rostral tip; and the presence of 25 dentary teeth. It also displays prosauropod characters such as a relatively long skull, the slope of the maxillary rostral profile, and teeth that do not have basically constricted crowns. The new specimen is more basal than Anchisaurus and represents the first basal sauropod dinosaur from the Early Jurassic of China.
  • Junchang Lue, Yoichi Azuma, Zhiming Dong, Rinchen Barsbold, Yoshitsugu Kobayashi, Yuong-Nam Lee
    GEOLOGICAL MAGAZINE 146 5 690 - 700 2009年09月 [査読有り][通常論文]
     
    New material of dsungaripterid pterosaurs from the Early Cretaceous of Tatal, western Mongolia, allows the diagnoses of Dsungaripteridae and Noripterus to be amended. All pterosaurs found at Tatal belong to Dsungaripteridae (either Dsungaripterus or Noripterus). The name Phobetor is a junior synonym of Noripterus. The differing shapes of the anterior tips of skulls, differing tooth morphologies and the coexistence of both Dsungaripterus and Noripterus may imply that they occupied distinct ecological niches.
  • Anthony R. Fiorillo, Stephen T. Hasiotis, Yoshitsugu Kobayashi, Carla Susanne Tomsich
    PALAIOS 24 7-8 466 - 472 2009年07月 [査読有り][通常論文]
     
    We report on the first record of a pterosaur from Alaska. This record consists of a single manus track from the lower part of the Upper Cretaceous Cantwell Formation in Denali National Park, Alaska, United States, making this the northernmost occurrence for this group of reptiles. The specimen is from deposits that record a low-lying floodplain with small lakes and ponds, dissected by small channels that fed a larger tributary stream on an active fan lobe. The dominant vegetation was comprised of conifers with an understory of ferns and horsetails.
  • Amy M. Balanoff, Xing Xu, Yoshimura Kobayashi, Yusuke Matsufune, Mark A. Norell
    AMERICAN MUSEUM NOVITATES 3651 3651 1 - 35 2009年06月 [査読有り][通常論文]
     
    We provide a description of the holotype skull Of the unusual oviraptorosaur Incisivosaurus gauthieri. Previous phylogenetic analyses have placed this taxon firmly within Oviraptorosauria near the base of the clade; however, until now only a cursory description of this important specimen was available. The presence of many primitive characteristics (e.g., maxillary and dentary teeth as well as an extended palate and rostrum) indicates that the observed similarities between avians and derived oviraptorids are convergences rather than shared derived characters. In addition, we clarify previous descriptions of several ambiguous anatomical features, most notably of the palate. We also employ computed tomographic (CT) analysis, which allows for a more complete description of the braincase and the reconstruction of an endocranial endocast. CT imagery reveals features that were before unobtainable, such as the presence of a replacement tooth behind the large rodentiform incisor in the premaxilla. This arrangement indicates that although the incisiform teeth of L gauthieri are morphologically distinct they are replaced in typical archosaurian fashion.
  • David A. Eberth, Yoshitsugu Kobayashi, Yuong-Nam Lee, Octavio Mateus, Francois Therrien, Darla K. Zelenitsky, Mark A. Norell
    JOURNAL OF VERTEBRATE PALEONTOLOGY 29 1 295 - 302 2009年03月 [査読有り][通常論文]
  • Katsuhiro Kubota, Yoshitsugu Kobayashi
    ACTA GEOLOGICA SINICA-ENGLISH EDITION 83 1 39 - 45 2009年02月 [査読有り][通常論文]
     
    The dentary diastema of iguanodontians has been considered to be related to its unique jaw mechanism for herbivorous adaptation. The dentary and diastema lengths of iguanodontians were measured and compared to elucidate the evolution of iguanodontian diastema. A gap in ratios between most non-hadrosaurid iguanodontians and hadrosaurids was observed, suggesting that all non-hadrosaurid iguanodontians, expect for Ouranosaurus nigeriensis and Protohadros byrdi, lack a diastema or have a short diastema, although some other taxa have been considered to have a long diastema in previous studies. In non-hadrosaurid iguanodontians, some large-sized forms, such as Iguanodon bernissartensis, Shuangmiaosaurus gilmorei, and possibly Eolambia caroljonesa, had a short diastema through ontogeny, whereas Ouranosaurus nigeriensis and Protohadros byrdi developed a long diastema convergently. The development of a long diastema of hadrosaurine hadrosaurids may be different from that of lambeosaurine hadrosaurids. Some hadrosaurunes (Edmontosaurus annectens, Edmontosaurus regalis, and Saurolophus angustirostris) may have developed a long diastema in the subadult stage and showed little elongation of dentary diastema through ontogeny. Lambeosaurines (Corythosaurus casuarius and Lambeosaurus lambei) tend to have a short diastema in the embryonic and subadult stages, and an elongated diastema from the subadult to adult stages.
  • Darla K. Zelenitsky, Francois Therrien, Yoshitsugu Kobayashi
    PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES 276 1657 667 - 673 2009年02月 [査読有り][通常論文]
     
    This research presents the first quantitative evaluation of the olfactory acuity in extinct theropod dinosaurs. Olfactory ratios (i.e. the ratio of the greatest diameter of the olfactory bulb to the greatest diameter of the cerebral hemisphere) are analysed in order to infer the olfactory acuity and behavioural traits in theropods, as well as to identify phylogenetic trends in olfaction within Theropoda. A phylogenetically corrected regression of olfactory ratio to body mass reveals that, relative to predicted values, the olfactory bulbs of (i) tyrannosaurids and dromaeosaurids are significantly larger, (ii) ornithomimosaurs and oviraptorids are significantly smaller, and (iii) ceratosaurians, allosauroids, basal tyrannosauroids, troodontids and basal birds are within the 95% CI. Relative to other theropods, olfactory acuity was high in tyrannosaurids and dromaeosaurids and therefore olfaction would have played an important role in their ecology, possibly for activities in low-light conditions, locating food, or for navigation within large home ranges. Olfactory acuity was the lowest in ornithomimosaurs and oviraptorids, suggesting a reduced reliance on olfaction and perhaps an omnivorous diet in these theropods. Phylogenetic trends in olfaction among theropods reveal that olfactory acuity did not decrease in the ancestry of birds, as troodontids, dromaeosaurids and primitive birds possessed typical or high olfactory acuity. Thus, the sense of smell must have remained important in primitive birds and its presumed decrease associated with the increased importance of sight did not occur until later among more derived birds.
  • Yuong-Nam Lee, Hang-Jae Lee, Junchang Lue, Yoshitsugu Kobayashi
    CRETACEOUS RESEARCH 29 2 345 - 353 2008年04月 [査読有り][通常論文]
     
    In 2004, fifty new pterosaur tracks were discovered in the Hasandong Formation (Lower Cretaceous), South Korea. They are preserved as natural casts on the surface of an isolated dark grey mudstone block (70 x 50 cm). Manus and pes imprints are very small, averaging 25.6 mm and 25.7 mm long, respectively. The manus imprints (N = 25) are tridactyl and digit 1, 11, Ill are strongly asymmetric. Fully plantigrade pes imprints (N = 25) were left by elongate metatarsals with short four digits (the ratio of digit to whole pes length is 2.6). There is no trace of the 5th phalanx of the pes. As these features clearly distinguish the Hadong tracks from the type species of the ichnogenus Pteraichnus, we assign them to a new species, Pteraichnus koreanensis. They are stratigraphically the oldest pterosaur tracks in Korea and are distinguished by size and morphology from the two pterosaur ichnotaxa, Haenamichnus uhangriensis and Pteraichnus isp., previously reported from the Uhangri and Haman formations. Pteraichnus koreanensis is the smallest pterosaur track currently reported from Asia. (c) 2007 Elsevier Ltd. All fights reserved.
  • Andrzej Kaim, Yoshitsugij Kobayashi, Hiroki Echizenya, Robert G. Jenkins, Kazushige Tanabe
    ACTA PALAEONTOLOGICA POLONICA 53 1 97 - 104 2008年02月 [査読有り][通常論文]
     
    The objective of this report is to document first Mesozoic occurrences of chemosynthesis-based communities developed on large marine reptile carcasses. Micro-grazing provannid gastropods (typical of chemosynthetic communities) are associated with plesiosaurid skeletons in the Upper Cretaceous deposits of Hokkaido, northern Japan. The cancellous bones of the examined plesiosaurid bones contain a ubiquity of iron sulfides within the bone trabeculae, which provides evidence of anaerobic sulfate reduction of the bone lipids. We also report numerous microborings in the bone trabeculae, which might result from the activity of sulfur-oxidizing bacteria. This finding addresses the hotly debated problem of the emergence and radiation of whale bone faunas. We postulate that vertebrate bone environments in the Northwest Pacific region were settled repeatedly by animals from a regional pool of chemosynthesis-based communities that flourished in the methane seeps and/or hot vents that were present during the Late Cretaceous-Miocene.
  • Phylogenetic position of Ornithomimosauria in Coelurosauria with comments on the relationship of ornithomimosaurs and alvarezsaurids.
    Kobayashi, Y
    Journal of Fossil Research 41 25 - 32 2008年 [査読有り][通常論文]
  • Junchang Lu, Yoshitsugu Kobayashi, Yuong-Nam Lee, Qiang Ji
    CRETACEOUS RESEARCH 28 2 272 - 276 2007年04月 [査読有り][通常論文]
     
    A psittacosaurid dinosaur from western Liaoning, China, possessing a pathological fibula is described. The pathological fibula is significantly different from a normal fibula, being shorter and much stouter, and with a distinct swelling on the shaft. The swollen portion (representing a mass of necrotic bone) of the fibula indicates that the animal survived for a relatively long time after becoming diseased, implying that the injuries to the fibula were not fatal, as has also been noted for some theropod dinosaurs. The pathological fibula may have been caused by the tubercle bacillus. (C) 2006 Elsevier Ltd. All rights reserved.
  • Dinosaurs from Japan
    Kobayashi, Y, Manabe, M, Ikegami, N, Tomida, Y, Hayakawa, H
    Papers from the 2005 Heyuan International Dinosaur Symposium. Beijing, Geological Publishing House 87 - 102 2006年 [査読有り][通常論文]
  • Kobayashi, Y, Tomida, Y, Kamei, T, Eguchi, T
    National Science Museum Monographs 35 1 - 121 国立科学博物館 2006年 [査読有り][通常論文]
     
    中期更新統の大阪層群から発見されたマチカネワニ(Toyotamaphimeia machikanensis)の模式標本について,本論文で詳細な再記載を行った.系統解析は,48分類群(2外群)の165形質を使って行った.その結果,420ステップで323個の最節約樹が得られた.厳密合意樹は,マチカネワニが明らかにマレーガビアル亜科(Tomistominae)に含まれることと,同亜科の唯一の現生種(マレーガビアルTomistoma schlegelii)の姉妹群であることを示している.さらに,系統樹の樹形は,マレーガビアル亜科がヨーロッパで起源したあとマチカネワニとマレーガビアルの分岐群が40万年前までに東アジアに拡散してきたことを支持し,これまでの研究と整合性を持つ.マチカネワニの定義についても改定した.従来は上顎の最大の歯は7番目と言われていたが,実際には12,13番目の方が7番目より大きい.上顎の7番より後方の歯はそれより前方の歯に比べてより密に並ぶ.上顎の8番から12番の歯は,かみ合ったときに下顎の歯の外側に位置するが,13番から16番の歯は対応する下顎歯と噛みあうことから,後方の歯は破砕の用途に使われたと考えられる.岸和田市から発見された類似のマレーガビアル亜科のワニ化石は,以前にはマチカネワニと考えられていたが,マチカネワニとは異なる分類群で,より原始的な種の可能性がある.
  • Ornithomimids from the Nemegt Formation of Mongolia.
    Kobayashi, Y, Barsbold, R
    Journal of Paleontological Society of Korea 22 195 - 207 2006年 [査読有り][通常論文]
  • Y Kobayashi, R Barsbold
    CANADIAN JOURNAL OF EARTH SCIENCES 42 9 1501 - 1521 2005年09月 [査読有り][通常論文]
     
    The holotype of Garudimimus brevipes, discovered from the Upper Cretaceous sediments of Mongolia and named by Barsbold in 1981, is redescribed in detail in this paper. Reexamination of the holotype reveals a great deal of anatomical information, which allows us to revise the original diagnosis of this taxon and make comparisons with other ornithomimosaur taxa to understand the evolution of ornithomimosaurs. This paper suggests that characters used to differentiate this taxon in the original paper (short ilia, short metatarsals, exposure of the proximal end of metatarsal III, presence of pedal digit 1, and absence of pleurocoels) are not apomorphies but represent the primitive conditions in ornithomimosaurs and are symplesiomorphics. Revised diagnoses are assigned for G. brevipes (posteriorly positioned jaw articulation, fossae at base of dorsal process of supraoccipital, paired depressions on neural spines of proximal caudal vertebra, and deep groove on lateral surface of pedal phalanges III-1 and III-2). Metatarsals of Garudimimus display a non-arctometatarsalian condition as in an Early Cretaceous form, Harpymimus, but the constriction of metatarsal III in Garudimimus is intermediate between Harpymimus and the arctometatarsalian condition in Gallimimus and other derived ornithomimosaurs (ornithomimids). Garudimimus is the only non-ornithomimid ornithomimosaur with edentulous jaws, which were probably covered by rhamphothecae. The loss of teeth with evolution of rhamphothecae and development of a cutting edge in the dentary of Garudimimus suggest the acquisition of feeding habits that included plucking food at the anterior portion of the jaw and cutting at the middle portion, similar to ornithomimids.
  • Anatomy of Harpymimus okladnikovi Barsbold and Perle, 1984 (Dinosauria; Theropoda) of Mongolia
    Kobayashi, Y, Barsbold, R
    Carnivorous Dinosaurs. Bloomington, Indiana University Press 97 - 126 2005年 [査読有り][通常論文]
  • J Lu, Y Kobayashi, CX Yuan, SA Ji, Q Ji
    ACTA GEOLOGICA SINICA-ENGLISH EDITION 79 6 766 - 769 2005年 [査読有り][通常論文]
     
    The cross-section and surface structures of wing membranes from the ctenochasmatid pterosaur Beipiaopterus chenianus were observed through a scanning electron microscope (SEM). The results show that the wing membrane contains a high density of blood vessels, implying strong thermoregulatory function, similar to that of a bat wing membrane. This is the first comparison of the microstructures of pterosaur wing membranes with those of the modem bat. It is inferred that a bat-like physiology exists, at least in relatively small pterosaurs suggesting that these pterosaurs were warm-blooded, active fliers.
  • Ornithomimosauria
    Makovicky, P, Kobayashi, Y, Currie, P
    The Dinosauria. 2nd ed. Berkeley, University of California Press 137 - 150 2004年 [査読有り][通常論文]
  • hylogeny of Ornithomimosauria and its paleobiogeographic implications.
    Kobayashi, Y, Barsbold, R
    Proceedings of the XIXth International Congress of Zoology, China 50 - 52 2004年 [査読有り][通常論文]
  • Phylogeny of Ornithomimosauria and its paleobiogeographic implications.
    Kobayashi, Y, Barsbold, R
    Proceedings of the XIXth International Congress of Zoology, China 50 - 52 2004年 [査読有り][通常論文]
  • Y Kobayashi, JC Lu
    ACTA PALAEONTOLOGICA POLONICA 48 2 235 - 259 2003年06月 [査読有り][通常論文]
     
    At least fourteen ornithomimid skeletons were recovered from the Upper Cretaceous Ulansuhai Formation in Nei Mongol (Inner Mongolia) Autonomous Region of China. They are assigned to a new genus and species, Sinornithomimus dongi. The anatomy of the species is described. Comparative and phylogenetic studies of ornithomimosaurs prove that these skeletons represent a new taxon that is more derived than Archaeornithomimus and more basal than the clade of [(Anserimimus + Galliminius) + [Struthionmimus + (Dromiceiomimus + Ornithomimus)]]. The phylogenetic analysis suggests that the structure of the hand is similar to Archaeornithomimus and represents an intermediate condition between the primitive (Harpymimus) and the derived (Anserimimus, Gallimimus, Struthiomimus, Dromiceiomimus, and Ornithomimus) conditions. The monophyly of Ornithomimidae is supported by a single synapomorphy (arctometatarsalian condition) in this analysis, indicating that the family is not as strongly supported as previously suggested. The analysis also implies that the shape of the rhamphotheca in North American taxa may have been different from that in Asian taxa. Previous study suggests herbivorous habits of this dinosaur based on characteristics of the gastroliths. The skeletons of Sinornithomimus were collected from a single monospecific bonebed with a high ratio of juvenile individuals (I I of the 14), suggesting gregarious behavior for protection from predators. The abundance of juveniles indicates high mortality of juveniles or a catastrophic mass mortality of a population with a high proportion of juveniles. An increase in the relative ratio of the tibia to femur through the ontogeny of Sinornithomimus suggests higher cursoriality in adult individuals than in juveniles.
  • A new iguanodontian (Dinosauria: Ornithopoda) from the Lower Cretaceous Kitadani Formation in Fukui Prefecture, Japan.
    Kobayashi, Y, Azuma, Y
    Journal of Vertebrate Paleontology 23 194 - 202 2003年 [査読有り][通常論文]
  • Y Kobayashi, DA Winkler, LL Jacobs
    PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES 269 1489 369 - 373 2002年02月 [査読有り][通常論文]
     
    Living placental and marsupial mammals (therians) use distinctive tooth-replacement patterns that have not yet been traced back fully to their time of divergence in the Early Cretaceous (>100 Myr ago). Slaughteria eruptens, a small 110 Myr old fossil mammal from Texas, USA, is near the base of that divergence. Using ultra-high-resolution X-ray CT analysis we demonstrate that Slaughteria preserves an unrecognized pattern of tooth replacement with simple posterior premolars replacing molariform precursors. Differing from both placentals that have a more complex posterior adult premolar, and from marsupials, in which only one premolar is replaced, Slaughteria provides the first direct evidence of a tooth-replacement pattern that is plausible for the common ancestor of all therians. By our interpretation Slaughteria has only one adult molar in place and contains two mental foramina in the jaw, thus changing characters that are critical to reconstruction of mammalian relationships and to species discrimination and interpretations of diversity for Early Cretaceous mammals.
  • Computed tomography of an anolis lizard in Dominican amber: systematic, taphonomic, biogeographic, and evolutionary implications.
    Polcyn, M, Rogers, J, Kobayashi, Y, Jacobs, L
    Palaeontologia Electronica 5 1 1 - 13 2002年 [査読有り][通常論文]
  • Biogeographic histories and chronologies of derived iguanodontians.
    Head, J, Kobayashi, Y
    VII International Symposium on Mesozoic Terrestrial Ecosystems, Argentina 107 - 111 1999年 [査読有り][通常論文]
  • The preliminary study of the dinosaur footprints from Huangshan, Anhui Province.
    Yu, X, Kobayashi, Y, L_, J
    Vertebrata Palasiatica 37 285 - 290 1999年 [査読有り][通常論文]
  • A new species of Ikechosaurus (Reptilia: Choristodera) from the Jiufutang Formation (Early Cretaceous) of Chifeng City, Inner Mongolia.
    L_, J, Kobayashi, Y, Li, Z
    Bulletin de l’Institut Royal des Sciences Naturelles Belgique 37 - 47 1999年 [査読有り][通常論文]
  • Herbivorous diet in an ornithomimid dinosaur
    小林快次
    Nature 402 480 - 481 1999年 [査読有り][通常論文]

MISC

  • 田中 公教, 小林 快次 日鳥学誌 67 (1) 57 -68 2018年 [査読無し][通常論文]
     
    ヘスペロルニス目Hesperornithiformesは，白亜紀前期アルビアン期-白亜紀後期マーストリヒチアン期の北半球に広く分布した歯のある潜水鳥類である．鳥類の進化史上初めて潜水適応した最古の潜水鳥類として知られており，これまで15属31種が報告されている．1871年に初めて骨格化石が発見されたヘスペロルニス<i>Hesperornis regalis</i>は，前肢が極端に発達しており，胸骨は竜骨突起を失い平たくなり，後肢は非常に発達していた．これらの形態的特徴から，ヘスペロルニスは白亜紀の飛翔能力を失った後肢推進性潜水鳥類と考えられる．この発見の後，アメリカ，カナダ，イギリス，スウェーデン，ロシア，カザフスタン，モンゴル，日本などから新たなヘスペロルニス目の化石が報告され，最古の潜水鳥類の進化の道のりが徐々に明らかになってきた．本稿では，現生鳥類の起源についての近年の研究のレビューを行い，現生鳥類がいつ頃から多様化を始めたのかを議論し，中生代の鳥類の最近の系統分類学を概観する．さらに，ヘスペロルニス目の発見からこれまでの研究を概説し，明らかになってきたヘスペロルニス目の生態や今後の研究課題について議論する．
  • 田中 康平, Darla K. Zelenitsky, Franç, ois Therrien, 小林 快次 日鳥学誌 67 (1) 25 -40 2018年 [査読無し][通常論文]
     
    主竜類（ワニ類，翼竜類，そして鳥類を含む恐竜類など）は，非常に多様で成功した陸上脊椎動物である．絶滅種（例，非鳥類型恐竜類）及び現生種（ワニ類及び鳥類）の営巣方法や営巣行動を理解することは，主竜類の進化や多様性を検討する上で重要である．しかしながら，恐竜類の営巣方法や営巣行動は，多くの場合，化石記録から直接観察できないため，かれらの営巣様式（巣の構造，抱卵行動，孵化日数など）は，卵・巣・胚化石から得られる特徴（クラッチサイズ，卵重，卵殻間隙率，胚の形態的特徴など）を用いて推定・復元される．非鳥類型恐竜類の巣や営巣行動は多様だったと考えられ，恐竜類を含め主竜類におけるこれらの形質の進化が議論できる．
  • A. R. Fiorillo, Y. Kobayashi, P. J. McCarthy, T. C. Wright, C. S. Tomsich Historical Biology 27 (6) 671 -682 2015年08月 [査読無し][通常論文]
     
    © 2014, © 2014 Taylor & Francis. We report on new records of pterosaur tracks from Alaska. Recent palaeontological investigations in the Lower Cantwell Formation of Denali National Park, central Alaska Range, Alaska, had resulted previously in the discovery of a single pterosaur manus track. Subsequent and ongoing investigation has shown that the track record for pterosaurs in this region is more robust. These new pterosaur records comprise large and small traces. The larger tracks are up to approximately 18 cm long and 6 cm wide. The smaller tracks are approximately 6 cm long and 4 cm wide. The assemblage of pterosaur traces from Denali National Park consists of manus impressions. The morphology of the pterosaur traces found in the Lower Cantwell Formation compares favourably with the morphology of the ichnogenus Pteraichnus. The presence of two very different body sizes of pterosaurs, along with the abundant record of fossil bird tracks, indicates the presence of ecological complexity among aerial vertebrates during the time that the sediments of the Lower Cantwell Formation were deposited. Sedimentological and palaeobotanical data, combined with the vertebrate ichnology record, offer details into how these aerial vertebrates were separated within this heterogenetic ecosystem.
  • Junchang Lu, Yoshitsugu Kobayashi, D. Charles Deeming, Yongqing Liu GEOSCIENCES JOURNAL 19 (2) 273 -280 2015年06月 [査読無し][通常論文]
     
    Post-natal parental care seems to have evolved numerous times in vertebrates. Among extant amniotes, it is present in crocodilians, birds, and mammals. However, evidence of this behavior is extremely rare in the fossil record and is only reported for two types of dinosaurs, and a varanopid 'pelycosaur'. Here we report new evidence for post-natal parental care in Philydrosaurus, a choristodere, from the Yixian Formation of western Liaoning Province, China. We review the fossil record of reproduction in choristoderes, and this represents the oldest record of post-natal parental care in diapsids to our knowledge.
  • 吉田純輝, CARPENTER Kenneth, 小林快次 日本古生物学会例会講演予稿集 164th 18 2015年01月30日 [査読無し][通常論文]
  • 田中公教, 小林快次, 栗原憲一, 加納学, FIORILLO Anthony 日本古生物学会例会講演予稿集 164th 21 2015年01月30日 [査読無し][通常論文]
  • 飯島正也, 小林快次, 樽野博幸, 渡辺克典 日本古生物学会例会講演予稿集 164th 39 2015年01月30日 [査読無し][通常論文]
  • 小林快次 日本古生物学会例会講演予稿集 164th 17 2015年01月30日 [査読無し][通常論文]
  • 森谷和浩, JENKINS Robert, ANDRZEJ Kaim, 小林快次, 越前谷宏紀 日本古生物学会例会講演予稿集 164th 32 2015年01月30日 [査読無し][通常論文]
  • 佐藤裕司, 小原正顕, 加藤茂弘, 伊藤謙, 高橋京子, 上田貴洋, 橋爪節也, 江口太郎, 渡辺克典, 小栗一輝, 林昭次, 小林快次 日本第四紀学会講演要旨集 44 169 2014年09月05日 [査読無し][通常論文]
  • Anthony R. Fiorillo, Stephen T. Hasiotis, Yoshitsugu Kobayashi GEOLOGY 42 (8) 719 -722 2014年08月 [査読無し][通常論文]
     
    The discovery of a new tracksite of mostly hadrosaurid dinosaur footprints, made by a herd living in an ancient high-latitude continental ecosystem, provides insight into the herd structure and behavior of northern polar dinosaurs and perspective on populations of large-bodied herbivores in an Arctic greenhouse world. This tracksite occurs in the Upper Cretaceous Cantwell Formation in the Alaska Range (Denali National Park, Alaska, United States), and it is the largest tracksite known from this far north. Preservation of the tracksite is exceptional: most tracks, regardless of size, contain skin impressions and they co-occur with well-preserved plant fossils and invertebrate trace fossils of terrestrial and aquatic insects. Statistical analyses of the tracks show that individuals of four different age classes of hadrosaurids lived together in a large social group. Our research results independently corroborate the growth curve for hadrosaurids proposed by paleohistologists that suggests that these dinosaurs experienced a period of rapid growth early in their life history.
  • 小林 快次 化石 (95) 49 -51 2014年03月 [査読無し][通常論文]
  • 小林快次 化学と生物 52 (2) 127 -130 2014年02月01日 [査読無し][通常論文]
  • 小林快次, 西村智弘, 櫻井和彦, 千葉謙太郎, 田中康平, 佐藤たまき 日本古生物学会例会講演予稿集 163rd 17 2014年01月24日 [査読無し][通常論文]
  • FIORILLO Anthony, 小林快次, HASIOTIS Stephen 日本古生物学会例会講演予稿集 163rd 16 2014年01月24日 [査読無し][通常論文]
  • 小林快次, LEE Yuong‐Nam, BARSBOLD Rinchen, ZELENITSKY Darla, 田中康平, LEE Hang‐Jae, 久保田克博 日本古生物学会例会講演予稿集 163rd 17 2014年01月24日 [査読無し][通常論文]
  • Masaya Iijima, Yoshitsugu Kobayashi Paleobiology 40 (4) 608 -624 2014年 [査読無し][通常論文]
     
    The pelvic structure in non-avian archosaurs plays a key role in understanding the evolution of terrestrial locomotor patterns because the pelvis contains major attachment sites for proximal hind limb musculature. In order to investigate patterns of pelvic evolution in archosaurs, this study compiled three pelvic indices, as well as femoral head orientation, for 92 archosaur taxa. With the metrics and a reconstructed supertree, we examined the correlated evolution of the pelvis and femur, the correlation among pelvic components, and temporal trends in the evolution of the pelvis. The result shows that archosaurs with medially directed femoral heads have more cranially shifted iliac centroids and more posteriorly rotated pubes than taxa with anteromedially directed femoral heads. The craniad shift of the iliac centroid might be correlated to the posterior rotation of pubis. The pelvic structures of pterosaurs, ornithischians, sauropods, and avetheropods occupy a different morphospace from basal archosaurs, pseudosuchians, basal dinosauromorphs, basal theropods, and basal sauropodomorphs in having more cranially expanded ilia, more posteriorly rotated pubes, and medially deflected femoral heads. This may imply that pterosaurs and those derived dinosaurs independently underwent similar shifts in thigh muscles and locomotion. The evolutionary model fitting supports the early-burst model for iliac and pubic metrics in more inclusive archosaur clades, indicating that larger changes of archosaur pelves occurred in early times of the clade's history.
  • 小林 快次 こどもの本 39 (7) 5 -5 2013年07月 [査読無し][通常論文]
  • 小林 快次 JGL : Japan geoscience letters 9 (2) 6 -8 2013年05月 [査読無し][通常論文]
  • 小林 快次 遺伝 : 生物の科学 67 (3) 378 -384 2013年05月 [査読無し][通常論文]
  • Anthony R. Fiorillo, Thomas L. Adams, Yoshitsugu Kobayashi CRETACEOUS RESEARCH 37 291 -299 2012年10月 [査読無し][通常論文]
     
    An unnamed nonmarine sedimentary package of rocks in southeastern Alaska in Wrangell-St. Elias National Park and Preserve has provided the first evidence of dinosaurs for this vast region. The rock unit is contained within the Wrangellia Terrane and exposures are of limited geographic extent. The rock unit is considered to be latest Cretaceous age. Sections are overwhelmingly dominated by extraformational conglomerates. Fine- to medium-grained light coloured sandstones are common and medium grey shales occur as minor components of the sections. Megafloral specimens indicate an abundance of horsetails, ferns and gymnosperm wood. Rather than two-dimensional impressions, most ferns are preserved in three dimensions, suggesting rapid burial. The abundance of charcoal in these rocks suggests that this area during deposition was also prone to ecological disturbance. Field parties found evidence of a small theropod and ornithopods. A single theropod pes impression is approximately 9 cm long and 7 cm wide. Attribution to the Theropoda was based on the sinusoidal shape of the impression of the middle digit. An ornithopod impression, identified by clearly blunt and rounded digit impressions, is approximately 22 cm long and 26 cm wide. All impressions are under tracks. (C) 2012 Elsevier Ltd. All rights reserved.
  • Kohei Tanaka, Junchang Lü, Yi Liu, Zhiqing Huang, Yoshitsugu Kobayashi, Dong Huang, Darla K. Zelenitsky Acta Geologica Sinica 86 294 -303 2012年04月01日 [査読無し][通常論文]
     
    The Zhutian and Dafeng formations (Upper Cretaceous) of the Heyuan Basin in northeastern Guangdong Province, China, have produced thousands of dinosaur eggs. Macromorphological features (egg diameter, egg shape, outer surface texture, and shell thickness) of 461 eggs were analyzed using non-destructive techniques and subjected to statistical analyses in order to assess their diversity and taxonomic affinities. Three types (1, 2 and 3) of eggs were discerned based on shape and outer surface morphology. Type 1 eggs are spherical to ellipsoidal in shape and have a rough surface. Three subtypes (Type 1-A-l, l-A-2, and 1-B) are apparent from scatter plots and cluster analyses of egg diameters and shell thickness. Type 2 eggs are elongate with linear ornamentation on the surface, and are comparable to eggs that belong to the oofamily Elongatoolithidae. Type 3 eggs are elongate with a smooth surface, and are assigned to the oofamily Prismatoolithidae. Macromorphological features of the various egg types suggest that Type 1 could have been laid by ornithischian, sauropod or therizinosaur dinosaurs, Type 2 by oviraptorids, and Type 3 by troodontids. This study represents the first comprehensive statistical analysis of macrofeatures of dinosaur eggs, and reveals taxonomic diversity in the dinosaurs that were laying eggs in the Upper Cretaceous Heyuan area heretofore unrecognized in skeletal remains.
  • 平山 廉, 大石 雅之, 真鍋 真, 對比地 孝亘, 薗田 哲平, 佐々木 和久, 小林 快次, 滝沢 利夫, 楠橋 直, 安藤 寿男, 三宅 優佳, 大倉 正敏 日本地質学会学術大会講演要旨 2012 (0) 282 -282 2012年 [査読無し][通常論文]
  • 平山 廉, 小林 快次, 薗田 哲平 化石研究会会誌 42 (2) 74 -82 2010年04月 [査読無し][通常論文]
  • Kobayashi Yoshitsugu 化石研究会会誌 41 (1) 25 -32 2008年09月 [査読無し][通常論文]
  • Kobayashi Yoshitsugu, Tomida Yukimitsu, Kamei Tadao, Eguchi Taro National Science Museum monographs 35 i -121 2006年 [査読無し][通常論文]
     
    中期更新統の大阪層群から発見されたマチカネワニ(Toyotamaphimeia machikanensis)の模式標本について,本論文で詳細な再記載を行った.系統解析は,48分類群(2外群)の165形質を使って行った.その結果,420ステップで323個の最節約樹が得られた.厳密合意樹は,マチカネワニが明らかにマレーガビアル亜科(Tomistominae)に含まれることと,同亜科の唯一の現生種(マレーガビアルTomistoma schlegelii)の姉妹群であることを示している.さらに,系統樹の樹形は,マレーガビアル亜科がヨーロッパで起源したあとマチカネワニとマレーガビアルの分岐群が40万年前までに東アジアに拡散してきたことを支持し,これまでの研究と整合性を持つ.マチカネワニの定義についても改定した.従来は上顎の最大の歯は7番目と言われていたが,実際には12,13番目の方が7番目より大きい.上顎の7番より後方の歯はそれより前方の歯に比べてより密に並ぶ.上顎の8番から12番の歯は,かみ合ったときに下顎の歯の外側に位置するが,13番から16番の歯は対応する下顎歯と噛みあうことから,後方の歯は破砕の用途に使われたと考えられる.岸和田市から発見された類似のマレーガビアル亜科のワニ化石は,以前にはマチカネワニと考えられていたが,マチカネワニとは異なる分類群で,より原始的な種の可能性がある.
  • Y Kobayashi, R Barsbold CANADIAN JOURNAL OF EARTH SCIENCES 42 (9) 1501 -1521 2005年09月 [査読無し][通常論文]
     
    The holotype of Garudimimus brevipes, discovered from the Upper Cretaceous sediments of Mongolia and named by Barsbold in 1981, is redescribed in detail in this paper. Reexamination of the holotype reveals a great deal of anatomical information, which allows us to revise the original diagnosis of this taxon and make comparisons with other ornithomimosaur taxa to understand the evolution of ornithomimosaurs. This paper suggests that characters used to differentiate this taxon in the original paper (short ilia, short metatarsals, exposure of the proximal end of metatarsal III, presence of pedal digit 1, and absence of pleurocoels) are not apomorphies but represent the primitive conditions in ornithomimosaurs and are symplesiomorphics. Revised diagnoses are assigned for G. brevipes (posteriorly positioned jaw articulation, fossae at base of dorsal process of supraoccipital, paired depressions on neural spines of proximal caudal vertebra, and deep groove on lateral surface of pedal phalanges III-1 and III-2). Metatarsals of Garudimimus display a non-arctometatarsalian condition as in an Early Cretaceous form, Harpymimus, but the constriction of metatarsal III in Garudimimus is intermediate between Harpymimus and the arctometatarsalian condition in Gallimimus and other derived ornithomimosaurs (ornithomimids). Garudimimus is the only non-ornithomimid ornithomimosaur with edentulous jaws, which were probably covered by rhamphothecae. The loss of teeth with evolution of rhamphothecae and development of a cutting edge in the dentary of Garudimimus suggest the acquisition of feeding habits that included plucking food at the anterior portion of the jaw and cutting at the middle portion, similar to ornithomimids.

書籍等出版物

共同研究・競争的資金等の研究課題

  • 文部科学省：科学研究費補助金(基盤研究(C))
    研究期間 : 2015年 -2017年 
    代表者 : 小林 快次
     
    デイノケイルスの含気化は、生命史上最も巨大化した動物である竜脚類を超えるものであった．この含気化はデイノケイルスの祖先系の種に見られることから，初期の段階で確立しており，進化とともに含気化が進むことで巨大化を可能としたと考えられる．また，頭骨は，広いくちばし，深い下顎，長い吻部と言った特徴を持つ．これらは採餌と食べ物の細分化を可能とした構造を持っていた．さらに，体内の胃石は円磨度が高く，胃における物理的な消化活動の高さを持っていたと考えられる．脊椎の長い神経棘は，他の恐竜よりもかなり複雑な構造をしている．長い神経棘には複数の機能があり，必要に応じてその機能のウエイトを変えて進化したと考察した．
  • 文部科学省：科学研究費補助金(基盤研究(C))
    研究期間 : 2012年 -2014年 
    代表者 : 小林 快次
     
    平成25年度は，獣脚類恐竜の植物食性の進化（テリジノサウルス類）と繁殖行動（テリジノサウルス類），および集団行動（オルニトミモサウルス類）の研究を行い，成果を挙げた．前年度に米国古脊椎動物学会と日本古生物学会で発表していた研究内容を，PlosOneに出版した．中国遼寧省から発見された恐竜を，新しいテリジノサウルス類恐竜としてジアンチャンゴサウルスと命名した．この研究によって，非鳥類型恐竜から鳥類へと進化するにしたがい、植物食性は段階を追って進化していったことを明らかにした．また，モンゴル南部のゴビ砂漠において，世界最大の獣脚類恐竜の営巣地を発見した．巣は込み合った状態で形成され，テリジノサウルス類は集団で行動し，営巣地を形成していたということを判明した．また，孵化率が非常に高いということから，テリジノサウルス類はワニ類のように巣の近くで天敵から卵を守り孵化率を上げていたと考えられる．どちらも，ニュース性が高く，NHKの全国ニュース等，多くマスコミに取り上げられた．
  • 文部科学省：科学研究費補助金(基盤研究(B))
    研究期間 : 2006年 -2009年 
    代表者 : 小林 快次, 金子 勝比古
     
    本研究によって、非鳥類型恐竜類から鳥類への脳や骨の進化過程において多くの情報を得ることができ、またそれらの境界を探ることができた。脳の進化過程としては、特に嗅覚の肥大・縮小というマクロの構造変化に注目することによって、非鳥類型恐竜から鳥類への生活や食性の変化を明らかにすることができた。このことは、中生代当時の生態系において、恐竜たちがどのようにニッチを奪い合って進化してきたかをみることが可能になり、これまで考えられてきた以上に複雑な進化をしていたことがわかった。また、これらの境界にあたるグループで鳥類に属すか否かの議論がされているオビラプトロサウルス類においても、脳の構造の視点から、これは非鳥類型恐竜に属すことが考えられ、体骨格の鳥類に類似した特徴は収斂進化であることを示す。活や食性の進化と同様、恐竜は複雑な進化を遂げながら、鳥類へ移行していったことがわかった。今後の課題としては、マクロなスケールではなくよりミクロな構造を分析することである。このさらなる研究によって、脳や神経システムからみた恐竜類の進化過程がより明らかになってくるであろう。

Copyright © MEDIA FUSION Co.,Ltd. All rights reserved.