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Publications
Publications (35)
The purpose of this study is to elucidate the interesting gait generation mechanism of crocodilians, which exhibit gaits seen in many quadrupedal animals. In our previous studies, we have focused on the passive interlocking mechanism in the crocodilian hindlimb musculoskeletal system. Through robotic validation, we have revealed that standing postu...
The herbivorous dinosaur clade Ceratopsia flourished in the northern hemisphere during the Late Jurassic to Late Cretaceous. Previous palaeobiogeographic studies have suggested that their initial diversification occurred in Asia, with early‐branching neoceratopsians extending their geographical range to North America sometime during the Barremian t...
In this study, the cam-like passive mechanism, known as the engage–disengage mechanism (EDM) of the intertarsal joint of ratites, and its design principles are investigated. This mechanism operates through the interplay of a muscle and three ligaments located on the medial and lateral sides of the intertarsal joint and the articular surface morphol...
The Upper Cretaceous successions are exposed at the Yagaan Khovil fossil locality in the central Gobi region, Mongolia. The successions comprise fluvial deposits that are divided into two units based on the lithological characteristics of the floodplain deposits. The lower unit (Unit 1) is characterized by eolian-influenced environments, whereas th...
The Nemegt Formation in the Gobi Desert, Mongolia, hosts abundant dinosaur and other vertebrate remains, the ages of which are uncertain due to a lack of radioactive dating. In order to more strictly constrain the depositional age of Nemegt Formation, we conducted U–Pb isotope, trace elements, and Y‐screening analyses using laser‐ablation inductive...
Despite the long history of research in the late Campanian Judith River Formation in northern Montana, most of the vertebrate fossils are represented by fragmentary remains, making precise taxonomic identifications difficult. Contrary to this, the partially contemporaneous Dinosaur Park Formation, Alberta, Canada is known for its tremendous fossil...
A monodominant Gryposaurus sp. bonebed in the lower unit of the Campanian Oldman Formation of southern Alberta is the oldest hadrosauroid bonebed documented in the province and the first described from the formation. The sedimentology of the locality and the taphonomy of the hadrosaurid material indicates that the bonebed represents an assemblage o...
Osteohistological data are commonly used to study the life history of extant and extinct tetrapods. While recent advances have permitted detailed reconstructions of growth patterns, physiology and other features using these data, they are most commonly used in assessments of ontogenetic stage and relative growth in extinct animals. These methods ha...
Hadrosaurid dinosaurs, the dominant large-bodied terrestrial herbivores in most Laurasian Late Cretaceous ecosystems, have an exceptional fossil record consisting of many species known from partial ontogenetic series, making them an ideal clade with which to conduct life-history studies. Previous research considered the Dinosaur Park Formation (DPF...
Mapping of fossil sites represents an important aspect of palaeontology, because the data collected are required for interpreting the taphonomic and depositional history of the site, as well as the palaeoecology and behavior of the organisms. Methods for mapping and documenting certain vertebrate fossil sites, such as trackways, have drastically ch...
en Zircon U–Pb dating of the Tonaru metagabbro body in the Sanbagawa metamorphic belt, southwest Japan, suggests that igneous events at ca 200–180 Ma were involved in the protolith formation. The trace element compositions of the Tonaru zircons are enriched in U (a fluid‐mobile element) and Sc (an amphibole‐buffered element), and depleted in Nb (a...
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
A nearly complete skeleton of a new hadrosaurid, Kamuysaurus japonicus gen. et sp. nov., was discovered from the outer shelf deposits of the Upper Cretaceous Hakobuchi Formation of the Yezo Group in Hobetsu area of Mukawa town in Hokkaido, Japan. Kamuysaurus belongs to the sub-clade of Hadrosaurinae, Edmontosaurini, and forms a monophyly with Laiya...
The pachyrostran centrosaurine dinosaur Pachyrhinosaurus perotorum is the geologically youngest (Maastrichtian, 70–68.5 Ma) centrosaurine, and latitudinally highest distributed ceratopsid yet known. Continued preparation of material collected from the type locality, the Kikak-Tegoseak Quarry, has produced more examples of cranial material from mult...
Medusaceratops lokii Ryan, Russell, and Hartman, 2010 is an enigmatic taxon of ceratopsid represented by partial parietals from the Mansfield bonebed in the Campanian Judith River Formation, Montana. Originally, all ceratopsid material collected from this bonebed was referred to the centrosaurine ceratopsid Albertaceratops , but subsequently two pa...
To date, only three pachycephalosaur specimens have been reported from the Nemegt Formation, two of which are holotypes (Homalocephale calathocercos and Prenocephale prenes) and all of which were collected from the classic Nemegt locality. Here, we describe several new cranial specimens from this formation, but which originate from Bügiin Tsav, Gur...
Nipponosaurus sachalinensis is the only definitive lambeosaurine hadrosaurid from Sakhalin Island of Russia. Previous studies suggested it was a member of Lambeosaurini (derived lambeosaurines). However, its phylogenetic status within Lambeosaurini remains controversial. In addition, some studies argued the juvenile ontogenetic stage of the holotyp...
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 hyp...
The long-term cooling trend from middle to late Eocene was punctuated by several large-scale climate perturbations that culminated in a shift to "icehouse" climates at the Eocene–Oligocene transition. We present radiolarian micro-fossil assemblage and foraminiferal oxygen and carbon stable isotope data from Deep Sea Drilling Project (DSDP) sites 27...
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 d...
Background
The paleoecology of desmostylians has been discussed controversially with a general consensus that desmostylians were aquatic or semi-aquatic to some extent. Bone microanatomy can be used as a powerful tool to infer habitat preference of extinct animals. However, bone microanatomical studies of desmostylians are extremely scarce.
Method...
Consensual phylogenetic tree illustrating the relationships between the taxa sampled for the study of the femur. Modified from [4], [47]–[51].
(TIF)
Consensual phylogenetic tree illustrating the relationships between the taxa sampled for the study of the rib. Modified from [4], [47]–[51].
(TIF)
Consensual phylogenetic tree illustrating the relationships between the taxa sampled for the study of the humerus. Modified from [4], [47]–[51].
(TIF)
Institutional abbreviations appearing in the inventor numbers of specimens.
(DOC)
Desmostylians are a group of extinct mammals known from the upper Oligocene through the
middle Miocene marine strata of the northern Pacific Rim. The paleoecology of extinct desmostylians
has been controversial since they were first discovered. The unique osteological
and dental morphologies have hindered a consensus on their paleoecology. Bone his...
Mid to late Eocene radiolarian faunas in the > 61 microns fraction from ca 70 samples of Southwest Pacific ODP Site 1172 were surveryed. All encountered morphotypes were classified when possible to species level. 158 species level morphotypes were determiend: 84 have been previously described and the remaiing 57 are in open nomenclature. A mixed as...
