Tetsuto Miyashita

Tetsuto Miyashita
Canadian Museum of Nature / Musée canadien de la nature

Ph.D.

About

39
Publications
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733
Citations

Publications

Publications (39)
Article
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Internal cranial anatomy is a challenging area to study in fossilized skulls because of small sample sizes and varied post-mortem preservational alterations. This difficulty has led to the lack of correspondence between results obtained from direct osteological observation and from more indirect reconstruction methods. This paper presents corrobora...
Article
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The evolutionary origin of the vertebrate jaw persists as a deeply puzzling mystery. More than 99% of living vertebrates have jaws, but the evolutionary sequence that ultimately gave rise to this highly successful innovation remains controversial. A synthesis of recent fossil and embryological findings offers a novel solution to this enduring puzzl...
Article
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Hagfish depart so much from other fishes anatomically that they were sometimes considered not fully vertebrate. They may represent: ( i ) an anatomically primitive outgroup of vertebrates (the morphology-based craniate hypothesis); or ( ii ) an anatomically degenerate vertebrate lineage sister to lampreys (the molecular-based cyclostome hypothesis)...
Article
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The vertebrate jaw is a versatile feeding apparatus. To function, it requires a joint between the upper and lower jaws, so jaw joint defects are often highly disruptive and difficult to study. To describe the consequences of jaw-joint dysfunction, we engineered two independent null alleles of a single jaw-joint marker gene, nkx3.2, in zebrafish. Th...
Article
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Ammocoetes—the filter-feeding larvae of modern lampreys—have long influenced hypotheses of vertebrate ancestry1–7. The life history of modern lampreys, which develop from a superficially amphioxus-like ammocoete to a specialized predatory adult, appears to recapitulate widely accepted scenarios of vertebrate origin. However, no direct evidence has...
Article
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Background Dinosaur eggs containing embryos are rare, limiting our understanding of dinosaur development. Recently, a clutch of subspherical dinosaur eggs was discovered while blasting for a construction project in the Upper Cretaceous red beds (Hekou Formation) of the Ganzhou Basin, Jiangxi Province, China. At least two of the eggs contain identif...
Article
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Scientists have long been searching for fossils of distant vertebrate ancestors. In the 1990s, mysterious fishlike forms—now known as yunnanozoans—were discovered at a 520-million-year-old Cambrian fossil site in the Yunnan province of China (1–3). More fishlike forms (e.g., Haikouichthys and Myllokunmingia) were reported from the same locality sho...
Article
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For sheer complexity, braincases are generally considered anatomically conservative. However, recent research on the braincases of tyrannosaurids have revealed extensive morphological variations. This line of inquiry has its root in Dale Russell’s review of tyrannosaurids in which he established Daspletosaurus torosus — a large tyrannosaurine from...
Article
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The regulated expansion of chondrocytes within growth plates and joints ensures proper skeletal development through adulthood. Mutations in the transcription factor NKX3.2 underlie Spondylo-megaepiphyseal-metaphyseal dysplasia (SMMD), which is characterized by skeletal defects including scoliosis, large epiphyses, wide growth plates, and supernumer...
Article
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Hagfishes and lampreys comprise cyclostomes, the earliest branching and sole surviving clade of the once diverse assemblage of jawless crown-group vertebrates. Lacking mineralized skeletons, both of the crown cyclostome lineages have notoriously poor fossil record. Particularly in the hagfish total group, †Myxinikela siroka Bardack, 1991 from the L...
Article
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The neural crest is regionalized along the anteroposterior axis, as demonstrated by foundational lineage-tracing experiments that showed the restricted developmental potential of neural crest cells originating in the head. Here, we explore how recent studies of experimental embryology, genetic circuits and stem cell differentiation have shaped our...
Preprint
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The vertebrate jaw is a versatile feeding apparatus that facilitated explosive diversification. Its functions require a joint between the upper and lower jaws, so jaw joint defects - such as osteoarthritis or even ankylosis - are often highly disruptive and difficult to study. To describe consequences of jaw joint dysfunction, we engineered two ind...
Chapter
Full-text available
Evolution and Development of Fishes - edited by Zerina Johanson January 2019
Article
In his correspondence, Markus Lambertz [1] raises some concerns about the phylogenetic placement and feather development of DIP-V-15103, the amber-entombed tail section that we recently reported [2] as fragmentary remains of a non-pygostylian coelurosaur (likely within the basal part of Coelurosauria). We here would like to respond to these concern...
Article
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Following extreme climatic warming events, Eocene Lagerstätten document aquatic and terrestrial vertebrate faunas surprisingly similar to modern counterparts. This transition in marine systems is best documented in the earliest teleost-dominated coral reef assemblage of Pesciara di Bolca, northern Italy, from near the end of the Eocene Climatic Opt...
Article
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In the two decades since the discovery of feathered dinosaurs [1-3], the range of plumage known from non-avialan theropods has expanded significantly, confirming several features predicted by developmentally informed models of feather evolution [4-10]. However, three-dimensional feather morphology and evolutionary patterns remain difficult to inter...
Article
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Evolution of serially similar structures has attracted interest since the infancy of comparative morphology and embryology. A long-standing assumption is that the serial patterning reflects ancestral metamerism, which persists in preconceived character polarity from a primitive state of polyisomerism (a series of identical or similar units) to a de...
Chapter
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Although the biology of hagfishes overall remains highly controversial, authors past and present unanimously agree on the crucial role of hagfish in elucidating the origin and early evolution of vertebrates. Still, an ongoing quest since the late 19th century has produced surprisingly little information on one of the most anticipated mysteries abou...
Article
A dinosaur tracksite in the Lower Jurassic Ziliujing Formation of Sichuan Province, China consists of a spectacular sub-vertical exposure, with multiple track-bearing levels and trackways showing parallel and bimodal orientations. Based on well-preserved material, the new ichnogenus and ichnospecies, Liujianpus shunan ichnogen. nov. ichnosp. nov. i...
Article
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ABSTRACT—Qijianglong guokr, gen. et sp. nov., represents a mamenchisaurid eusauropod from the Late Jurassic of southern China. The holotype consists of an incomplete skull, partly articulated axial skeleton, and fragmentary appendicular skeleton. A well-preserved braincase and skull roof provide rare insights into the poorly known neurocranial anat...
Article
Many sauropod ghost lineages cross the Middle Jurassic, indicating a time interval that requires increased sampling. A wide taxonomic spectrum of sauropodomorphs is known from the Middle Jurassic of China, but the braincase of a new sauropod, named here Nebulasaurus taito gen. et sp. nov., is distinct. Nebulasaurus is sister taxon to Spinophorosaur...
Article
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Living vertebrate diversity comprises hagfishes and lampreys (Cyclostomata), elasmobranchs and holocephalans (Chondrichthyes), and bony fish which include tetrapods (Osteichthyes). Based on dissections and an extensive comparative analysis, we provide an updated overview of the anatomy, homologies and evolution of cyclostome and chondrichthyan ceph...
Article
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A high density of tracks resembling both the ichnogenera Chelonipus and Emydhipus occurs on surfaces of the Lower Cretaceous Tugulu Group at the Huangyangquan tracksite in Wuerhe district (Xinjiang Uyghur Autonomous Region, northwestern China). These ichnotaxa are especially known from Central Europe where they have been found in Triassic and Upper...
Article
Tracks of large theropods and a single sauropod footprint are reported from red beds at Beikeshan locality in the Middle Jurassic Chuanjie Formation, of Lufeng County, near the large World Dinosaur Valley Park complex. The Chuanjie theropod tracks are assigned to the ichnogenus Eubrontes and the large sauropod track is given the provisional label B...
Article
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Hagfish represent an ancient lineage of boneless and jawless vertebrates. Among several curious behaviors they exhibit, solitary individuals in one dominant genus of hagfish (Eptatretus spp.) regularly rest in a tightly coiled posture. We present the first systematic treatment of this distinctive behavior. Individual northeastern Pacific hagfish (E...
Article
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Here we describe two instances of pathological vertebral fusion in two genera of sauropodomorph dinosaurs from the Early Jurassic Lufeng Formation in Yunnan, China. The first is a specimen, of Lufengosaurus huenei with two fused cervical vertebrae, and the other is a specimen of the Lufeng basal sauropod, with two fused caudal vertebrae. Both patho...
Article
The largest specimen of the four-winged dromaeosaurid dinosaur Microraptor gui includes preserved gut contents. Previous reports of gut contents and considerations of functional morphology have indicated that Microraptor hunted in an arboreal environment. The new specimen demonstrates that this was not strictly the case, and offers unique insights...
Chapter
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Internal carotid circulation is arguably one of the most intensively analyzed morphological characters in turtle systematics and, thus, it is critical for understanding turtle phylogeny. I used landmark-based geometric mor-phometrics to facilitate a quantitative analysis of variation in turtle skull shape and osteological correlates of the internal...
Article
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Two skeletons of the large compsognathid Sinocalliopteryx gigas include intact abdominal contents. Both specimens come from the Jianshangou Beds of the lower Yixian Formation (Neocomian), Liaoning, China. The holotype of S. gigas preserves a partial dromaeosaurid leg in the abdominal cavity, here attributed to Sinornithosaurus. A second, newly-disc...
Article
2010. Variation in premaxillary tooth count and a developmental abnormality in a tyrannosaurid dinosaur. Acta Palaeontologica Polonica 55 (4): 635–643. Premaxillary tooth count tends to be stable amongst toothed dinosaurs, and most theropods have four teeth in each pre− maxilla. Only one case of bilaterally asymmetric variation is known in theropod...
Article
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Predation is an important selective agent in the evolution of gastropod shell form. The adaptive value of shell elongation, however, has received relatively little attention in the context of predation. Arguments for its functional significance include the hypothesis that shell elongation facilitates soft tissue withdrawal inside the shell, thus el...
Article
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This study reports on a new microvertebrate locality from the Campanian (c 74 My) fluvial beds of the Wapiti Formation in the Grande Prairie area (west-central Alberta, Canada). This locality represents deposition on a low-gradient, waterlogged alluvial plain approximately 300 km to the north west of the Bearpaw Sea. Detailed sedimentological analy...

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