The anatomy and palaeobiology of the early armoured dinosaur Scutellosaurus lawleri (Ornithischia: Thyreophora) from the Kayenta Formation (Lower Jurassic) of Arizona
The armoured dinosaurs, Thyreophora, were a diverse clade of ornithischians known from the Early Jurassic to the end of the Cretaceous. During the Middle and Late Jurassic, the thyreophorans radiated to evolve large body size, quadrupedality, and complex chewing mechanisms, and members of the group...
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The Royal Society
2021-07-01
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| Series: | Royal Society Open Science |
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| Online Access: | https://royalsocietypublishing.org/doi/10.1098/rsos.201676 |
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| author | Benjamin T. Breeden Thomas J. Raven Richard J. Butler Timothy B. Rowe Susannah C. R. Maidment |
| author_facet | Benjamin T. Breeden Thomas J. Raven Richard J. Butler Timothy B. Rowe Susannah C. R. Maidment |
| author_sort | Benjamin T. Breeden |
| collection | DOAJ |
| description | The armoured dinosaurs, Thyreophora, were a diverse clade of ornithischians known from the Early Jurassic to the end of the Cretaceous. During the Middle and Late Jurassic, the thyreophorans radiated to evolve large body size, quadrupedality, and complex chewing mechanisms, and members of the group include some of the most iconic dinosaurs, including the plated Stegosaurus and the club-tailed Ankylosaurus; however, the early stages of thyreophoran evolution are poorly understood due to a paucity of relatively complete remains from early diverging thyreophoran taxa. Scutellosaurus lawleri is generally reconstructed as the earliest-diverging thyreophoran and is known from over 70 specimens from the Lower Jurassic Kayenta Formation of Arizona, USA. Whereas Scutellosaurus lawleri is pivotal to our understanding of character-state changes at the base of Thyreophora that can shed light on the early evolution of the armoured dinosaurs, the taxon has received limited study. Herein, we provide a detailed account of the osteology of Scutellosaurus lawleri, figuring many elements for the first time. Scutellosaurus lawleri was the only definitive bipedal thyreophoran. Histological studies indicate that it grew slowly throughout its life, possessing lamellar-zonal tissue that was a consequence neither of its small size nor phylogenetic position, but may instead be autapomorphic, and supporting other studies that suggest thyreophorans had lower basal metabolic rates than other ornithischian dinosaurs. Faunal diversity of the Kayenta Formation in comparison with other well-known Early Jurassic-aged dinosaur-bearing formations indicates that there was considerable spatial and/or environmental variation in Early Jurassic dinosaur faunas. |
| first_indexed | 2024-04-11T00:38:55Z |
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| institution | Directory Open Access Journal |
| issn | 2054-5703 |
| language | English |
| last_indexed | 2024-04-11T00:38:55Z |
| publishDate | 2021-07-01 |
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| series | Royal Society Open Science |
| spelling | doaj.art-2d2d5f3d49d14df2a4d8e9fd166fc4e62023-01-06T11:30:38ZengThe Royal SocietyRoyal Society Open Science2054-57032021-07-018710.1098/rsos.201676The anatomy and palaeobiology of the early armoured dinosaur Scutellosaurus lawleri (Ornithischia: Thyreophora) from the Kayenta Formation (Lower Jurassic) of ArizonaBenjamin T. Breeden0Thomas J. Raven1Richard J. Butler2Timothy B. Rowe3Susannah C. R. Maidment4Department of Geology and Geophysics, University of Utah, Salt Lake City, UT, USADepartment of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UKSchool of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UKJackson School of Geosciences, The University of Texas at Austin, Austin, TX, USADepartment of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UKThe armoured dinosaurs, Thyreophora, were a diverse clade of ornithischians known from the Early Jurassic to the end of the Cretaceous. During the Middle and Late Jurassic, the thyreophorans radiated to evolve large body size, quadrupedality, and complex chewing mechanisms, and members of the group include some of the most iconic dinosaurs, including the plated Stegosaurus and the club-tailed Ankylosaurus; however, the early stages of thyreophoran evolution are poorly understood due to a paucity of relatively complete remains from early diverging thyreophoran taxa. Scutellosaurus lawleri is generally reconstructed as the earliest-diverging thyreophoran and is known from over 70 specimens from the Lower Jurassic Kayenta Formation of Arizona, USA. Whereas Scutellosaurus lawleri is pivotal to our understanding of character-state changes at the base of Thyreophora that can shed light on the early evolution of the armoured dinosaurs, the taxon has received limited study. Herein, we provide a detailed account of the osteology of Scutellosaurus lawleri, figuring many elements for the first time. Scutellosaurus lawleri was the only definitive bipedal thyreophoran. Histological studies indicate that it grew slowly throughout its life, possessing lamellar-zonal tissue that was a consequence neither of its small size nor phylogenetic position, but may instead be autapomorphic, and supporting other studies that suggest thyreophorans had lower basal metabolic rates than other ornithischian dinosaurs. Faunal diversity of the Kayenta Formation in comparison with other well-known Early Jurassic-aged dinosaur-bearing formations indicates that there was considerable spatial and/or environmental variation in Early Jurassic dinosaur faunas.https://royalsocietypublishing.org/doi/10.1098/rsos.201676DinosauriaOrnithischiaThyreophoraKayenta FormationJurassicScutellosaurus lawleri |
| spellingShingle | Benjamin T. Breeden Thomas J. Raven Richard J. Butler Timothy B. Rowe Susannah C. R. Maidment The anatomy and palaeobiology of the early armoured dinosaur Scutellosaurus lawleri (Ornithischia: Thyreophora) from the Kayenta Formation (Lower Jurassic) of Arizona Royal Society Open Science Dinosauria Ornithischia Thyreophora Kayenta Formation Jurassic Scutellosaurus lawleri |
| title | The anatomy and palaeobiology of the early armoured dinosaur Scutellosaurus lawleri (Ornithischia: Thyreophora) from the Kayenta Formation (Lower Jurassic) of Arizona |
| title_full | The anatomy and palaeobiology of the early armoured dinosaur Scutellosaurus lawleri (Ornithischia: Thyreophora) from the Kayenta Formation (Lower Jurassic) of Arizona |
| title_fullStr | The anatomy and palaeobiology of the early armoured dinosaur Scutellosaurus lawleri (Ornithischia: Thyreophora) from the Kayenta Formation (Lower Jurassic) of Arizona |
| title_full_unstemmed | The anatomy and palaeobiology of the early armoured dinosaur Scutellosaurus lawleri (Ornithischia: Thyreophora) from the Kayenta Formation (Lower Jurassic) of Arizona |
| title_short | The anatomy and palaeobiology of the early armoured dinosaur Scutellosaurus lawleri (Ornithischia: Thyreophora) from the Kayenta Formation (Lower Jurassic) of Arizona |
| title_sort | anatomy and palaeobiology of the early armoured dinosaur scutellosaurus lawleri ornithischia thyreophora from the kayenta formation lower jurassic of arizona |
| topic | Dinosauria Ornithischia Thyreophora Kayenta Formation Jurassic Scutellosaurus lawleri |
| url | https://royalsocietypublishing.org/doi/10.1098/rsos.201676 |
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