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Last Updated :2024/07/25

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Master

Affiliation (Master)

  • Hokkaido University Museum

Affiliation (Master)

  • Hokkaido University Museum

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Profile and Settings

Profile and Settings

  • Name (Japanese)

    Kobayashi

  • Name (Kana)

    Yoshitsugu

  • Name

    201501081886466779

Alternate Names

Achievement

Research Interests

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

Research Areas

  • Natural sciences / Biogeoscience

Research Experience

  • 2019 - Today Osaka University The Museum of Osaka University
  • 2019 - Today Hokkaido University The Hokkaido University Museum
  • 2013 - 2019 Osaka University The Museum of Osaka University
  • 2009 - 2019 Hokkaido University The Hokkaido University Museum
  • 2008 - 2009 Hokkaido University The Hokkaido University Museum
  • 2005 - 2008 Hokkaido University The Hokkaido University Museum

Awards

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

Published Papers

  • Masaya Iijima, Arata Momohara, Yoshitsugu Kobayashi, Shoji Hayashi, Tadahiro Ikeda, Hiroyuki Taruno, Katsunori Watanabe, Masahiro Tanimoto, Sora Furui
    Palaeogeography, Palaeoclimatology, Palaeoecology 496 346 - 360 0031-0182 2018/05/01 [Refereed][Not invited]
     
    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 0031-0182 2018/04/01 [Refereed][Not invited]
     
    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 0031-0182 2018/04/01 [Refereed][Not invited]
     
    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 0031-0182 2018/04/01 [Refereed][Not invited]
     
    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 0031-0182 2018/04/01 [Refereed][Not invited]
     
    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 [Refereed][Not invited]
  • Comparative limb propotions reveal differential locomotor morphofunctions of alligatoroids and crocodyloids.
    Iijima, M, Kubo, T, Kobayashi, Y
    Royal Society Open Science 5 171774  2018 [Refereed][Not invited]
  • Darla K. Zelenitsky, Francois Therrien, Kohei Tanaka, Yoshitsugu Kobayashi, Christopher L. DeBuhr
    CRETACEOUS RESEARCH 74 181 - 187 0195-6671 2017/06 [Refereed][Not invited]
     
    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 [Refereed][Not invited]
  • 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 [Refereed][Not invited]
  • 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 [Refereed][Not invited]
  • 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 [Refereed][Not invited]
  • Masaya Iijima, Keiichi Takahashi, Yoshitsugu Kobayashi
    JOURNAL OF ASIAN EARTH SCIENCES 124 94 - 101 1367-9120 2016/07 [Refereed][Not invited]
     
    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 0891-2963 2016/02 [Refereed][Not invited]
  • 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 0891-2963 2016/02 [Refereed][Not invited]
     
    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 0883-1351 2015/09 [Refereed][Not invited]
     
    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  2045-2322 2015/07 [Refereed][Not invited]
     
    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 0028-0836 2014/11 [Refereed][Not invited]
     
    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  1471-2148 2014/11 [Refereed][Not invited]
     
    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 0091-7613 2014/08 [Refereed][Not invited]
     
    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 [Refereed][Not invited]
  • 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 [Refereed][Not invited]
  • 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 [Refereed][Not invited]
  • Iijima, M, Kobayashi, Y
    Paleobiology 40 608 - 624 2014 [Refereed][Not invited]
  • Hanyong Pu, Yoshitsugu Kobayashi, Junchang Lü, Li Xu, Yanhua Wu, Huali Chang, Jiming Zhang, Songhai Jia
    PLoS ONE 8 (5) e63423  1932-6203 2013/05/29 [Refereed][Not invited]
     
    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  1932-6203 2013/03 [Refereed][Not invited]
     
    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 0195-6671 2012/10 [Refereed][Not invited]
     
    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 0036-8075 2012/10 [Refereed][Not invited]
     
    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 1000-9515 2012/04 [Refereed][Not invited]
     
    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 0195-6671 2011/04 [Refereed][Not invited]
     
    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 [Refereed][Not invited]
  • 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 [Refereed][Not invited]
  • 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 1000-9515 2011 [Refereed][Not invited]
     
    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 1477-2019 2011 [Refereed][Not invited]
     
    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 0028-1042 2011/01 [Refereed][Not invited]
     
    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 化石研究会 42 (2) 74 - 82 0387-1924 2010 [Refereed][Not invited]
  • Lue Junchang, Yoshitsugu Kobayashi, Li Tianguang, Zhong Shimin
    ACTA GEOLOGICA SINICA-ENGLISH EDITION 84 (6) 1336 - 1342 1000-9515 2010 [Refereed][Not invited]
     
    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 0016-7568 2009/09 [Refereed][Not invited]
     
    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 0883-1351 2009/07 [Refereed][Not invited]
     
    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 0003-0082 2009/06 [Refereed][Not invited]
     
    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 0272-4634 2009/03 [Refereed][Not invited]
  • Katsuhiro Kubota, Yoshitsugu Kobayashi
    ACTA GEOLOGICA SINICA-ENGLISH EDITION 83 (1) 39 - 45 1000-9515 2009/02 [Refereed][Not invited]
     
    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 0962-8452 2009/02 [Refereed][Not invited]
     
    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 0195-6671 2008/04 [Refereed][Not invited]
     
    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 0567-7920 2008/02 [Refereed][Not invited]
     
    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 [Refereed][Not invited]
  • Junchang Lu, Yoshitsugu Kobayashi, Yuong-Nam Lee, Qiang Ji
    CRETACEOUS RESEARCH 28 (2) 272 - 276 0195-6671 2007/04 [Refereed][Not invited]
     
    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 [Refereed][Not invited]
  • Kobayashi, Y, Tomida, Y, Kamei, T, Eguchi, T
    National Science Museum Monographs 国立科学博物館 35 1 - 121 1342-9574 2006 [Refereed][Not invited]
     
    The holotype of Toyotamaphimeia machikanensis, discovered from the Middle Pleistocene sediments of the Osaka Group in Osaka Prefecture of Japan, is redescribed in details in this study. Phylogenetic analysis is conducted with 165 characters for 48 taxa (two outgroups). The analysis produces 323 most parsimonious trees of 420 steps. The strict consensus tree suggests that Toyotamaphimeia is deeply nested within the clade Tomistominae and is a sister taxon to the only extant tomistomine crocodylian, Tomistoma schlegelii. The topology of the phylogenetic trees implies that tomistomines originated in Europe as previously suggested and the clade of Toyotamaphimeia machikanensis plus Tomistoma schlegelii dispersed into eastern Asia by or prior to 400 thoudsand years ago. Diagnoses of Toyotamaphimeia machikanensis are also revised. Although previous studies stated that maxillary tooth 7 was the largest in Toyotamaphimeia, maxillary teeth twelfth and thirteenth maxillary teeth are actually larger than the seventh. Maxillary teeth posterior to the seventh are more closely placed than anterior ones. Maxillary teeth eighth to twelfth are placed lateral to the dentary teeth in occlusion, whereas maxillary teeth thirteenth to sixteenth meet with corresponding dentary teeth, suggesting that posterior teeth of the maxilla and dentary may have been used for crushing. A tomistomine crocodylian from the Kishiwada Town, previously referred to Toyotamaphimeia machikanensis, is not comparable with the holotype of Toyotamaphimeia and considered here as a different taxon, possibly more primitive than Toyotamaphimeia machikanensis.
  • Ornithomimids from the Nemegt Formation of Mongolia.
    Kobayashi, Y, Barsbold, R
    Journal of Paleontological Society of Korea 22 195 - 207 2006 [Refereed][Not invited]
  • Y Kobayashi, R Barsbold
    CANADIAN JOURNAL OF EARTH SCIENCES 42 (9) 1501 - 1521 0008-4077 2005/09 [Refereed][Not invited]
     
    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 [Refereed][Not invited]
  • J Lu, Y Kobayashi, CX Yuan, SA Ji, Q Ji
    ACTA GEOLOGICA SINICA-ENGLISH EDITION 79 (6) 766 - 769 1000-9515 2005 [Refereed][Not invited]
     
    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 [Refereed][Not invited]
  • hylogeny of Ornithomimosauria and its paleobiogeographic implications.
    Kobayashi, Y, Barsbold, R
    Proceedings of the XIXth International Congress of Zoology, China 50 - 52 2004 [Refereed][Not invited]
  • Phylogeny of Ornithomimosauria and its paleobiogeographic implications.
    Kobayashi, Y, Barsbold, R
    Proceedings of the XIXth International Congress of Zoology, China 50 - 52 2004 [Refereed][Not invited]
  • Y Kobayashi, JC Lu
    ACTA PALAEONTOLOGICA POLONICA 48 (2) 235 - 259 0567-7920 2003/06 [Refereed][Not invited]
     
    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 [Refereed][Not invited]
  • Y Kobayashi, DA Winkler, LL Jacobs
    PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES 269 (1489) 369 - 373 0962-8452 2002/02 [Refereed][Not invited]
     
    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 [Refereed][Not invited]
  • Biogeographic histories and chronologies of derived iguanodontians.
    Head, J, Kobayashi, Y
    VII International Symposium on Mesozoic Terrestrial Ecosystems, Argentina 107 - 111 1999 [Refereed][Not invited]
  • The preliminary study of the dinosaur footprints from Huangshan, Anhui Province.
    Yu, X, Kobayashi, Y, L_, J
    Vertebrata Palasiatica 37 285 - 290 1999 [Refereed][Not invited]
  • 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 [Refereed][Not invited]
  • Herbivorous diet in an ornithomimid dinosaur
    Kobayashi, Y, Lü, J, Dong, Z, Barsbold, R, Azuma, Y, Tomida, Y
    Nature 402 480 - 481 1999 [Refereed][Not invited]

MISC

  • TANAKA Tomonori, KOBAYASHI Yoshitsugu  Jpn. J. Ornithol.  67-  (1)  57  -68  2018  [Not refereed][Not invited]
     
    Hesperornithiformes were toothed, foot-propelled diving birds and among the most widely distributed groups of birds in the Cretaceous (Late Albian to Maastrichtian) in the Northern Hemisphere. The first species of this group, <i>Hesperornis regalis</i> was discovered from the Niobrara Formation (Upper Santonian) in Kansas in 1871. <i>H. regalis</i> had extremely reduced forelimbs, powerful hind limbs, and a non-keeled sternum. Taking into consideration the osteological features mentions above, this huge diving bird was obviously a flightless foot-propelled diver. Currently, Cretaceous Hesperornithiformes are recognized as the oldest diving birds in the avian evolutionary history. Thirty-one species and at least fifteen genera have been named so far. Most of the known hesperornithiform remains have been recovered from the marine deposits of the Western Interior Seaway in North America, especially from Kansas and South Dakota in USA and Manitoba and Saskatchewan in Canada. In Europe, some hesperornithiform remains have been found from the Cretaceous deposits of the Turgai Strait (Russia and Kazakhstan), but Hesperornithiformes are extremely rare in Asia where they are only known from three remains from Mongolia and Japan. Current phylogenetic analyses of Mesozoic birds suggest that these diving birds are one of the closest relatives of the Neornithes (modern birds). In this article, we review the current knowledge of the origin of the Neornithes, the phylogeny of Mesozoic birds, and hesperornithiform osteology and paleoecology. We also discuss future prospects for research into these oldest diving birds.
  • TANAKA Kohei, ZELENITSKY Darla K, THERRIEN Franç, ois, KOBAYASHI Yoshitsugu  Jpn. J. Ornithol.  67-  (1)  25  -40  2018  [Not refereed][Not invited]
     
    Archosaurs (e.g., crocodilians, pterosaurs, and dinosaurs including birds) are the most diverse and successful clade of terrestrial vertebrates. An understanding of the nesting methods and behaviors of both extinct (e.g., non-avian dinosaurs) and extant archosaurs (i.e., crocodilians and birds) is crucial for the advancement of our understanding of the evolution and diversification of this clade. The nesting methods and behavior of extinct taxa cannot be directly observed from the fossil record, thus aspects of nesting (i.e., nest type, incubation behavior, and incubation period) may only be inferred and reconstructed based on certain features of fossil eggs, nests, and embryos (e.g., clutch size, egg mass, eggshell porosity, and embryonic osteology). Nests and nesting behaviors were likely to have been diverse among non-avian dinosaurs, and the evolution of these features in archosaurs is discussed.
  • A. R. Fiorillo, Y. Kobayashi, P. J. McCarthy, T. C. Wright, C. S. Tomsich  HISTORICAL BIOLOGY  27-  (6)  671  -682  2015/08  [Not refereed][Not invited]
     
    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 18cm long and 6cm wide. The smaller tracks are approximately 6cm long and 4cm 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  2015/06  [Not refereed][Not invited]
     
    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.
  • YOSHIDA JUNKI, CARPENTER KENNETH, KOBAYASHI YOSHITSUGU  日本古生物学会例会講演予稿集  164th-  18  2015/01/30  [Not refereed][Not invited]
  • TANAKA TOMONORI, KOBAYASHI YOSHITSUGU, KURIHARA KEN'ICHI, KANO MANABU, FIORILLO ANTHONY  日本古生物学会例会講演予稿集  164th-  21  2015/01/30  [Not refereed][Not invited]
  • IIJIMA MASAYA, KOBAYASHI YOSHITSUGU, TARUNO HIROYUKI, WATANABE KATSUNORI  日本古生物学会例会講演予稿集  164th-  39  2015/01/30  [Not refereed][Not invited]
  • KOBAYASHI YOSHITSUGU  日本古生物学会例会講演予稿集  164th-  17  2015/01/30  [Not refereed][Not invited]
  • MORIYA KAZUHIRO, JENKINS ROBERT, ANDRZEJ KAIM, KOBAYASHI YOSHITSUGU, ECHIZEN'YA HIROKI  日本古生物学会例会講演予稿集  164th-  32  2015/01/30  [Not refereed][Not invited]
  • SATO HIROSHI, OHARA MASAAKI, KATO SHIGEHIRO, ITO KEN, TAKAHASHI KYOKO, UEDA TAKAHIRO, HASHIZUME SETSUYA, EGUCHI TARO, WATANABE KATSUNORI, OGURI KAZUKI, HAYASHI SHOJI, KOBAYASHI YOSHITSUGU  日本第四紀学会講演要旨集  44-  169  2014/09/05  [Not refereed][Not invited]
  • Anthony R. Fiorillo, Stephen T. Hasiotis, Yoshitsugu Kobayashi  GEOLOGY  42-  (8)  719  -722  2014/08  [Not refereed][Not invited]
     
    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  2014/03  [Not refereed][Not invited]
  • KOBAYASHI YOSHITSUGU  化学と生物  52-  (2)  127  -130  2014/02/01  [Not refereed][Not invited]
  • KOBAYASHI YOSHITSUGU, NISHIMURA TOMOHIRO, SAKURAI KAZUHIKO, CHIBA KENTARO, TANAKA KOHEI, SATO TAMAKI  日本古生物学会例会講演予稿集  163rd-  17  2014/01/24  [Not refereed][Not invited]
  • FIORILLO ANTHONY, KOBAYASHI YOSHITSUGU, HASIOTIS STEPHEN  日本古生物学会例会講演予稿集  163rd-  16  2014/01/24  [Not refereed][Not invited]
  • KOBAYASHI YOSHITSUGU, LEE YUONG-NAM, BARSBOLD RINCHEN, ZELENITSKY DARLA, TANAKA KOHEI, LEE HANG-JAE, KUBOTA KATSUHIRO  日本古生物学会例会講演予稿集  163rd-  17  2014/01/24  [Not refereed][Not invited]
  • Masaya Iijima, Yoshitsugu Kobayashi  Paleobiology  40-  (4)  608  -624  2014  [Not refereed][Not invited]
     
    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  2013/07  [Not refereed][Not invited]
  • 小林 快次  JGL : Japan geoscience letters  9-  (2)  6  -8  2013/05  [Not refereed][Not invited]
  • 小林 快次  遺伝 : 生物の科学  67-  (3)  378  -384  2013/05  [Not refereed][Not invited]
  • Anthony R. Fiorillo, Thomas L. Adams, Yoshitsugu Kobayashi  CRETACEOUS RESEARCH  37-  291  -299  2012/10  [Not refereed][Not invited]
     
    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  2012/04/01  [Not refereed][Not invited]
     
    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.
  • Hirayama Ren, Oishi Masayuki, Manabe Makoto, Tsuihiji Takanobu, Sonoda Teppei, Sasaki Kazuhisa, Kobayashi Yoshitsugu, Takizawa Toshio, Kusuhashi Nao, Ando HIsao, Miyake Yuka, Okura Masatoshi  Annual Meeting of the Geological Society of Japan  2012-  (0)  282  -282  2012  [Not refereed][Not invited]
  • 平山 廉, 小林 快次, 薗田 哲平  化石研究会会誌  42-  (2)  74  -82  2010/04  [Not refereed][Not invited]
  • Kobayashi Yoshitsugu  化石研究会会誌  41-  (1)  25  -32  2008/09  [Not refereed][Not invited]
  • Kobayashi Yoshitsugu, Tomida Yukimitsu, Kamei Tadao, Eguchi Taro  National Science Museum monographs  35-  i  -121  2006  [Not refereed][Not invited]
     
    The holotype of Toyotamaphimeia machikanensis, discovered from the Middle Pleistocene sediments of the Osaka Group in Osaka Prefecture of Japan, is redescribed in details in this study. Phylogenetic analysis is conducted with 165 characters for 48 taxa (two outgroups). The analysis produces 323 most parsimonious trees of 420 steps. The strict consensus tree suggests that Toyotamaphimeia is deeply nested within the clade Tomistominae and is a sister taxon to the only extant tomistomine crocodylian, Tomistoma schlegelii. The topology of the phylogenetic trees implies that tomistomines originated in Europe as previously suggested and the clade of Toyotamaphimeia machikanensis plus Tomistoma schlegelii dispersed into eastern Asia by or prior to 400 thoudsand years ago. Diagnoses of Toyotamaphimeia machikanensis are also revised. Although previous studies stated that maxillary tooth 7 was the largest in Toyotamaphimeia, maxillary teeth twelfth and thirteenth maxillary teeth are actually larger than the seventh. Maxillary teeth posterior to the seventh are more closely placed than anterior ones. Maxillary teeth eighth to twelfth are placed lateral to the dentary teeth in occlusion, whereas maxillary teeth thirteenth to sixteenth meet with corresponding dentary teeth, suggesting that posterior teeth of the maxilla and dentary may have been used for crushing. A tomistomine crocodylian from the Kishiwada Town, previously referred to Toyotamaphimeia machikanensis, is not comparable with the holotype of Toyotamaphimeia and considered here as a different taxon, possibly more primitive than Toyotamaphimeia machikanensis.
  • Y Kobayashi, R Barsbold  CANADIAN JOURNAL OF EARTH SCIENCES  42-  (9)  1501  -1521  2005/09  [Not refereed][Not invited]
     
    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.

Books etc

Research Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2015 -2017 
    Author : Kobayashi Yoshitsugu
     
    The degree of pneumatization of the Deinocheirus was beyond sauropods, which is the largest terrestrial animals in the life history. Since this pneumatization is present in a basal form of this group, it was established at the early stage, and this dinosaur group became gigantic by progress of pneumatization along with evolution. Also, the skull has features characterized as a wide beak, a deep lower jaw, and a long snout. They had a structure that made it possible to divide foraging and food. Furthermore, it is thought that gastroliths in the body had a high degree of circularity and had high physical digestive activity in the stomach. Long neural spines have a much more complicated morphology than other dinosaurs. It was considered that long nural spines had multiple functions and evolved by changing the weight of the function as necessary.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2012 -2014 
    Author : KOBAYASHI Yoshitsugu
     
    This study focuses on the diet evolution of theropods dinosaurs and its implication to the origin of birds. The evolution of herbivory in theropod dinosaurs is a key to understand the shift from non-avian to avian dinosaurs. My study suggests that the diversity of herbivory in theropods is greater than previously thought, and the extremities are therizinosaurs and ornithomimosaurs. Therizinosaurs developed more efficient oral and gastrointestinal digestion, whereas ornithomimosaurs had gastroliths and muscular stomach to become herbivory. This diversity in digestion may have had led to the diversity in species and ecology, which may a driving force to the bird origin.
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2006 -2009 
    Author : Yoshitsugu KOBAYASHI, Katsuhiko KANEKO
     
    This study provides informative data to elucidate the evolutionary processes of body and brain from non-avian dinosaurs to birds and the transition of these animals. Specifically, a part of this study focused on large scaled morphology, such as the olfactory bulb for smelling, which reveals the changes of life style and feeding behaviors. This perspective is important to understand the paleoecology and food chain during the Mesozoic and the competition of niches among these animals. Oviraptorosaurs is one of good examples for the transitional dinosaurs between non-avian dinosaurs and birds. In this study, we analyze the changes in body and brain morphology to discuss if oviraptorosaurs belong to birds or avian features in this group is convergent. We concludes that the latter because brain features are more like non-avian dinosaurs, showing complex history of thetransition between non-avian dinosaurs to birds. In the future study, we need to much smaller scale in terms of the structures of brain and nervous system, which will providemore information about the evolution of dinosaurs.

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