1
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Windholz GJ, Carballido JL, Coria RA, Zurriaguz VL, Rauhut OWM. How pneumatic were the presacral vertebrae of dicraeosaurid (Sauropoda: Diplodocoidea) dinosaurs? Biol J Linn Soc Lond 2022. [DOI: 10.1093/biolinnean/blac131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Abstract
Skeletal pneumaticity implies bone invasion via air sacs that are diverticula of the respiratory system. Among extant vertebrates, this feature is found only in birds, and in extinct taxa it occurs in saurischian dinosaurs and pterosaurs. The sauropod axial skeleton is characterized by having a complex architecture of laminae and fossae that have usually been related to some degree of pneumaticity. We examined the external anatomy of the presacral vertebrae of two dicraeosaurid sauropods holotype specimens, Amargasaurus cazaui and Brachytrachelopan mesai, and obtained computed tomography scan images from mid- and posterior cervical vertebrae of both specimens and an anterior dorsal vertebra of Brachytrachelopan. In all cases, we recognized a ‘procamerate’ internal pneumatization pattern, confirming previous hypotheses that dicraeosaurid vertebral pneumaticity is reduced relative to other eusauropod taxa. Thus, pneumatic diverticula were present in Amargasaurus, Brachytrachelopan, Dicraeosaurus, Pilmatueia and, possibly, other dicraeosaurid sauropods, but these diverticula did not invade their presacral vertebrae extensively. Furthermore, we found that the more pneumatic dicraeosaurid taxa, with some exceptions, occupy a basal position within Dicraeosauridae. There is some variability in pneumaticity among dicraeosaurids from Gondwana, with Pilmatueia achieving the highest degree of pneumatization.
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Affiliation(s)
- Guillermo J Windholz
- Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro , Río Negro , Argentina
- IIPG UNRN Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET) , Av. Roca 1242, (R8332EXZ) General Roca, Río Negro , Argentina
| | - José L Carballido
- CONICET-Museo Paleontológico ‘Egidio Feruglio’ , Fontana 140, (9100) Trelew, Chubut , Argentina
| | - Rodolfo A Coria
- CONICET-Museo Carmen Funes , Av. Córdoba 55, (8318) Plaza Huincul, Neuquén , Argentina
| | - Virginia L Zurriaguz
- Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro , Río Negro , Argentina
- IIPG UNRN Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET) , Av. Roca 1242, (R8332EXZ) General Roca, Río Negro , Argentina
| | - Oliver W M Rauhut
- Department for Earth and Environmental Sciences and GeoBio-Center, SNSB-Bayerische Staatssammlung für Paläontologie und Geologie, Ludwig-Maximilian University Munich , Richard-Wagner-Straße 10, 80333, Munich , Germany
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2
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Pêgas RV, Costa FR, Kellner AWA. Reconstruction of the adductor chamber and predicted bite force in pterodactyloids (Pterosauria). Zool J Linn Soc 2021. [DOI: 10.1093/zoolinnean/zlaa163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
The reconstruction of jaw muscles is critical in establishing potential cranial functions; however, myological studies of extinct groups that have no descendants are difficult to perform and test. This is particularly true for pterosaurs, a group of extinct flying reptiles that present a plethora of cranial morphologies, suggesting different functions and feeding habits. Here we present a first attempt to reconstruct the adductor musculature of the pterodactyloid skull in detail, using osteological correlates and the extant phylogenetic bracketing method. Using these reconstructions, we estimate bite force for nine selected species and investigate implications for potential dietary habits.
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Affiliation(s)
- Rodrigo V Pêgas
- Laboratory of Vertebrate Paleontology and Animal Behavior, Universidade Federal do ABC, São Bernardo do Campo, São Paulo, Brazil
| | - Fabiana R Costa
- Laboratory of Vertebrate Paleontology and Animal Behavior, Universidade Federal do ABC, São Bernardo do Campo, São Paulo, Brazil
| | - Alexander W A Kellner
- Laboratory of Systematics and Taphonomy of Fossil Vertebrates, Departamento de Geologia e Paleontologia, Universidade Federal do Rio de Janeiro, Museu Nacional, Rio de Janeiro, Brazil
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3
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Quantitative assessment of the vertebral pneumaticity in an anhanguerid pterosaur using micro-CT scanning. Sci Rep 2021; 11:18718. [PMID: 34548510 PMCID: PMC8455612 DOI: 10.1038/s41598-021-97856-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 08/30/2021] [Indexed: 11/08/2022] Open
Abstract
Research on the postcranial skeletal pneumaticity in pterosaurs is common in the literature, but most studies present only qualitative assessments. When quantitative, they are done on isolated bones. Here, we estimate the Air Space Proportion (ASP) obtained from micro-CT scans of the sequence from the sixth cervical to the fourth dorsal vertebra of an anhanguerine pterosaur to understand how pneumaticity is distributed in these bones. Pneumatisation of the vertebrae varied between 68 and 72% of their total volume. The neural arch showed higher ASP in all vertebrae. Anhanguerine vertebral ASP was generally higher than in sauropod vertebrae but lower than in most extant birds. The ASP observed here is lower than that calculated for the appendicular skeleton of other anhanguerian pterosaurs, indicating the potential existence of variation between axial and appendicular pneumatisation. The results point to a pattern in the distribution of the air space, which shows an increase in the area occupied by the trabecular bone in the craniocaudal direction of the vertebral series and, in each vertebra, an increase of the thickness of the trabeculae in the zygapophyses. This indicates that the distribution of pneumatic diverticula in anhanguerine vertebrae may not be associated with stochastic patterns.
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4
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Williams CJ, Pani M, Bucchi A, Smith RE, Kao A, Keeble W, Ibrahim N, Martill DM. Helically arranged cross struts in azhdarchid pterosaur cervical vertebrae and their biomechanical implications. iScience 2021; 24:102338. [PMID: 33997669 PMCID: PMC8101050 DOI: 10.1016/j.isci.2021.102338] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 02/10/2021] [Accepted: 03/17/2021] [Indexed: 11/30/2022] Open
Abstract
Azhdarchid pterosaurs, the largest flying vertebrates, remain poorly understood, with fundamental aspects of their palaeobiology unknown. X-ray computed tomography reveals a complex internal micro-architecture for three-dimensionally preserved, hyper-elongate cervical vertebrae of the Cretaceous azhdarchid pterosaur, Alanqa sp. Incorporation of the neural canal within the body of the vertebra and elongation of the centrum result in a "tube within a tube" supported by helically distributed trabeculae. Linear elastic static analysis and linearized buckling analysis, accompanied with a finite element model, reveal that as few as 50 trabeculae increase the buckling load by up to 90%, implying that a vertebra without the trabeculae is more prone to elastic instability due to axial loads. Subsuming the neural tube into the centrum tube adds considerable stiffness to the cervical series, permitting the uptake of heavy prey items without risking damage to the cervical series, while at the same time allowing considerable skeletal mass reduction.
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Affiliation(s)
- Cariad J Williams
- School of the Environment, Geography and Geosciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth, PO1 3QL, UK.,Center for Paleontology, Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Forbes Natural History Building 1816 S. Oak Street, Champaign, IL 61820, USA
| | - Martino Pani
- School of Mechanical and Design Engineering, University of Portsmouth, Anglesea Building, Anglesea Road, Portsmouth PO1 3DJ, UK
| | - Andrea Bucchi
- School of Mechanical and Design Engineering, University of Portsmouth, Anglesea Building, Anglesea Road, Portsmouth PO1 3DJ, UK
| | - Roy E Smith
- School of the Environment, Geography and Geosciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth, PO1 3QL, UK
| | - Alexander Kao
- School of Engineering, University of Portsmouth, Portland Building, Portland Street, PO1 3DJ, Portsmouth, UK.,Elettra Synchrotron Trieste, Science Park, 34149 Basovizza TS, Italy
| | - William Keeble
- Faculty of Technology, University of Portsmouth, Anglesea Building, Anglesea Road, Portsmouth PO1 3DJ, UK
| | - Nizar Ibrahim
- School of the Environment, Geography and Geosciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth, PO1 3QL, UK
| | - David M Martill
- School of the Environment, Geography and Geosciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth, PO1 3QL, UK
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5
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Moore AJ. Vertebral pneumaticity is correlated with serial variation in vertebral shape in storks. J Anat 2021; 238:615-625. [PMID: 32981054 PMCID: PMC7855073 DOI: 10.1111/joa.13322] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 08/23/2020] [Accepted: 09/09/2020] [Indexed: 11/29/2022] Open
Abstract
Birds and their ornithodiran ancestors are unique among vertebrates in exhibiting air-filled sinuses in their postcranial bones, a phenomenon called postcranial skeletal pneumaticity. The factors that account for serial and interspecific variation in postcranial skeletal pneumaticity are poorly understood, although body size, ecology, and bone biomechanics have all been implicated as influencing the extent to which pneumatizing epithelia invade the skeleton and induce bone resorption. Here, I use high-resolution computed-tomography to holistically quantify vertebral pneumaticity in members of the neognath family Ciconiidae (storks), with pneumaticity measured as the relative volume of internal air space. These data are used to describe serial variation in extent of pneumaticity and to assess whether and how pneumaticity varies with the size and shape of a vertebra. Pneumaticity increases dramatically from the middle of the neck onwards, contrary to previous predictions that cervical pneumaticity should decrease toward the thorax to maintain structural integrity as the mass and bending moments of the neck increase. Although the largest vertebrae sampled are also the most pneumatic, vertebral size cannot on its own account for serial or interspecific variation in extent of pneumaticity. Vertebral shape, as quantified by three-dimensional geometric morphometrics, is found to be significantly correlated with extent of pneumaticity, with elongate vertebrae being less pneumatic than craniocaudally short and dorsoventrally tall vertebrae. Considered together, the results of this study are consistent with the hypothesis that shape- and position-specific biomechanics influence the amount of bone loss that can be safely tolerated. These results have potentially important implications for the evolution of vertebral morphology in birds and their extinct relatives.
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Affiliation(s)
- Andrew J. Moore
- Department of Biological SciencesThe George Washington UniversityWashingtonDCUSA,Department of Anatomical SciencesStony Brook UniversityStony BrookNYUSA
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6
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Larramendi A, Paul GS, Hsu SY. A review and reappraisal of the specific gravities of present and past multicellular organisms, with an emphasis on tetrapods. Anat Rec (Hoboken) 2020; 304:1833-1888. [PMID: 33258532 DOI: 10.1002/ar.24574] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 11/13/2020] [Accepted: 11/17/2020] [Indexed: 11/09/2022]
Abstract
The density, or specific gravity (SG), of organisms has numerous important implications for their form, function, ecology, and other facets of beings living and dead, and it is especially necessary to apply SG values that are as accurate as practical when estimating their masses which is itself a critical aspect of living things. Yet a comprehensive review and analysis of this notable subject of anatomy has never been conducted and published. This is such an effort, being as extensive as possible with the data on hand, bolstered by some additional observations, and new work focusing on extinct animals who densities are least unknown: pterosaurs and dinosaurs with extensive pneumatic complexes, including the most sophisticated effort to date for a sauropod. Often difficult to determine even via direct observation, techniques for obtaining the best possible SG data are explained and utilized, including observations of floating animals. Neutral specific gravity (NSG) is proposed as the most important value for tetrapods with respiratory tracts of fluctuating volume. SGs of organisms range from 0.08 to 2.6, plant tissues from 0.08 to 1.39, and vertebrates from about 0.75 (some giant pterosaurs) to 1.2 (those with heavy armor and/or skeletons). Tetrapod NSGs tend to be somewhat higher than widely thought, especially those theropod and sauropod dinosaurs and pterosaurs with air-sacs because respiratory system volume is usually measured at maximum inhalation in birds. Also discussed is evidence that the ratio of the mass of skeletons relative to total body mass has not been properly assayed in the past.
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Affiliation(s)
- Asier Larramendi
- Eofauna Scientific Research, Errondo 6, 10c, Donostia, Basque Country, 20010, Spain
| | | | - Shu-Yu Hsu
- Eofauna Scientific Research, Errondo 6, 10c, Donostia, Basque Country, 20010, Spain
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7
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Aranciaga Rolando M, Garcia Marsà J, Novas F. Histology and pneumaticity of Aoniraptor libertatem (Dinosauria, Theropoda), an enigmatic mid-sized megaraptoran from Patagonia. J Anat 2020; 237:741-756. [PMID: 32470191 PMCID: PMC7495275 DOI: 10.1111/joa.13225] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 11/29/2022] Open
Abstract
Aoniraptor libertatem is a mid-sized megaraptoran that comes from the Late Cretaceous (Turonian) Huincul Formation at Río Negro province, Patagonia, Argentina. In this study, we conducted a detailed analysis of pneumaticity of the sacrum and tail of Aoniraptor. This shows a complex structure within these vertebrae, being composed by small diverticulae surrounding large pneumatic canals and a central chamber that opens outside through pleurocoels or pneumatic canals. Further, we carried out a histologic analysis which confirms the pneumatic nature of these anatomical features. Both analyses found that chevrons in Aoniraptor were invaded by pneumaticity, a feature that appears to be unique to this taxon. In addition, a comparative analysis between Aoniraptor and other theropods (e.g. Gualicho and other megaraptorans) was carried out. This resulted in the modification of previous schemes about the evolution of pneumaticity through Theropoda, the finding of some evolutionary pneumatic traits through Megaraptora, and the usefulness of pneumatic traits as a taxonomic tool.
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Affiliation(s)
- Mauro Aranciaga Rolando
- Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’Consejo Nacional de Investigaciones Científicas y Técnicas – CONICETBuenos AiresArgentina
- Museo Municipal de Ciencias Naturales “Carlos Ameghino”MercedesArgentina
| | - Jordi Garcia Marsà
- Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’Consejo Nacional de Investigaciones Científicas y Técnicas – CONICETBuenos AiresArgentina
| | - Fernando Novas
- Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’Consejo Nacional de Investigaciones Científicas y Técnicas – CONICETBuenos AiresArgentina
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8
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Navarro CA, Martin-Silverstone E, Stubbs TL. Morphometric assessment of pterosaur jaw disparity. ROYAL SOCIETY OPEN SCIENCE 2018; 5:172130. [PMID: 29765665 PMCID: PMC5936930 DOI: 10.1098/rsos.172130] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 03/26/2018] [Indexed: 05/28/2023]
Abstract
Pterosaurs were a successful group of Mesozoic flying reptiles. They were the first vertebrate group to achieve powered flight and varied enormously in morphology and ecology, occupying a variety of niches and developing specialized feeding strategies. Ecomorphological principles suggest this variation should be reflected by great morphological diversity in the lower jaw, given that the mandible served as the primary apparatus for prey acquisition. Here we present the first study of mandibular shape disparity in pterosaurs and aim to characterize major aspects of variation. We use a combination of geometric morphometric approaches, incorporating both outline analysis using elliptical Fourier analysis and semi-landmark approaches. Our results show that morphological convergence is prevalent and many pterosaurs, belonging to diverse dietary groups and subclades, overlap in morphospace and possessed relatively simple 'rod-shaped' jaws. There is no clear trend of size distributions in pterosaur mandibular morphospace, and larger forms are widely distributed. Additionally, there is limited functional signal within pterosaur lower jaw morphospace. Instead, the development of a large anterior ventral crest represents the major component of disparity. This suggests that a socio-sexual trait was a key driver for innovation in pterosaur lower jaw shape.
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Affiliation(s)
- Charlie A. Navarro
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, UK
| | - Elizabeth Martin-Silverstone
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, UK
- Ocean and Earth Science, National Oceanography Centre, University of Southampton, European Way, Southampton SO14 3ZH, UK
| | - Thomas L. Stubbs
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, UK
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9
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Funston GF, Martin-Silverstone E, Currie PJ. The first pterosaur pelvic material from the Dinosaur Park Formation (Campanian) and implications for azhdarchid locomotion. Facets (Ott) 2017. [DOI: 10.1139/facets-2016-0067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A partial pterosaur pelvis from the Campanian Dinosaur Park Formation of Canada adds to our knowledge of Late Cretaceous pterosaurs. The pelvis is tentatively referred to Azhdarchidae and represents the first pelvic material from a North American azhdarchid. The morphology of the ilium is bizarre compared with other pterosaurs: it is highly pneumatized, the preacetabular process tapers anteriorly, and muscle scars show that it would have anchored strong adductor musculature for the hindlimb. The acetabulum is deep and faces ventrolaterally, allowing the limb to be positioned underneath the body. These features support previous suggestions that azhdarchids were well adapted to terrestrial locomotion.
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Affiliation(s)
- Gregory F. Funston
- Department of Biological Sciences, CW 405, Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Elizabeth Martin-Silverstone
- Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, Southampton SO14 3ZH, UK
| | - Philip J. Currie
- Department of Biological Sciences, CW 405, Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, Canada
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10
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Martin-Silverstone E, Witton MP, Arbour VM, Currie PJ. A small azhdarchoid pterosaur from the latest Cretaceous, the age of flying giants. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160333. [PMID: 27853614 PMCID: PMC5108964 DOI: 10.1098/rsos.160333] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 07/20/2016] [Indexed: 06/01/2023]
Abstract
Pterosaur fossils from the Campanian-Maastrichtian of North America have been reported from the continental interior, but few have been described from the west coast. The first pterosaur from the Campanian Northumberland Formation (Nanaimo Group) of Hornby Island, British Columbia, is represented here by a humerus, dorsal vertebrae (including three fused notarial vertebrae), and other fragments. The elements have features typical of Azhdarchoidea, an identification consistent with dominance of this group in the latest Cretaceous. The new material is significant for its size and ontogenetic stage: the humerus and vertebrae indicate a wingspan of ca 1.5 m, but histological sections and bone fusions indicate the individual was approaching maturity at time of death. Pterosaurs of this size are exceedingly rare in Upper Cretaceous strata, a phenomenon commonly attributed to smaller pterosaurs becoming extinct in the Late Cretaceous as part of a reduction in pterosaur diversity and disparity. The absence of small juveniles of large species-which must have existed-in the fossil record is evidence of a preservational bias against small pterosaurs in the Late Cretaceous, and caution should be applied to any interpretation of latest Cretaceous pterosaur diversity and success.
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Affiliation(s)
- Elizabeth Martin-Silverstone
- Ocean and Earth Science, National Oceanography Centre, University of Southampton, European Way, Southampton SO14 3ZH, UK
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol BS8 1RJ, UK
| | - Mark P. Witton
- School of Earth and Environmental Sciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth PO1 3QL, UK
| | - Victoria M. Arbour
- Paleontology Research Lab, North Carolina Museum of Natural Sciences, Raleigh, NC, USA
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA
| | - Philip J. Currie
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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11
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Riede T, Eliason CM, Miller EH, Goller F, Clarke JA. Coos, booms, and hoots: The evolution of closed‐mouth vocal behavior in birds. Evolution 2016; 70:1734-46. [DOI: 10.1111/evo.12988] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 05/12/2016] [Accepted: 06/13/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Tobias Riede
- Department of Physiology Midwestern University Glendale Arizona 85308
| | - Chad M. Eliason
- Department of Geological Sciences The University of Texas at Austin Texas 78712
| | - Edward H. Miller
- Department of Biology, Memorial University St. John's, Newfoundland and Labrador A1B 3X9 Canada
| | - Franz Goller
- Department of Biology University of Utah Salt Lake City 84112 Utah
| | - Julia A. Clarke
- Department of Geological Sciences The University of Texas at Austin Texas 78712
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12
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Watanabe A, Eugenia Leone Gold M, Brusatte SL, Benson RBJ, Choiniere J, Davidson A, Norell MA. Vertebral Pneumaticity in the Ornithomimosaur Archaeornithomimus (Dinosauria: Theropoda) Revealed by Computed Tomography Imaging and Reappraisal of Axial Pneumaticity in Ornithomimosauria. PLoS One 2015; 10:e0145168. [PMID: 26682888 PMCID: PMC4684312 DOI: 10.1371/journal.pone.0145168] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 11/30/2015] [Indexed: 11/19/2022] Open
Abstract
Among extant vertebrates, pneumatization of postcranial bones is unique to birds, with few known exceptions in other groups. Through reduction in bone mass, this feature is thought to benefit flight capacity in modern birds, but its prevalence in non-avian dinosaurs of variable sizes has generated competing hypotheses on the initial adaptive significance of postcranial pneumaticity. To better understand the evolutionary history of postcranial pneumaticity, studies have surveyed its distribution among non-avian dinosaurs. Nevertheless, the degree of pneumaticity in the basal coelurosaurian group Ornithomimosauria remains poorly known, despite their potential to greatly enhance our understanding of the early evolution of pneumatic bones along the lineage leading to birds. Historically, the identification of postcranial pneumaticity in non-avian dinosaurs has been based on examination of external morphology, and few studies thus far have focused on the internal architecture of pneumatic structures inside the bones. Here, we describe the vertebral pneumaticity of the ornithomimosaur Archaeornithomimus with the aid of X-ray computed tomography (CT) imaging. Complementary examination of external and internal osteology reveals (1) highly pneumatized cervical vertebrae with an elaborate configuration of interconnected chambers within the neural arch and the centrum; (2) anterior dorsal vertebrae with pneumatic chambers inside the neural arch; (3) apneumatic sacral vertebrae; and (4) a subset of proximal caudal vertebrae with limited pneumatic invasion into the neural arch. Comparisons with other theropod dinosaurs suggest that ornithomimosaurs primitively exhibited a plesiomorphic theropod condition for axial pneumaticity that was extended among later taxa, such as Archaeornithomimus and large bodied Deinocheirus. This finding corroborates the notion that evolutionary increases in vertebral pneumaticity occurred in parallel among independent lineages of bird-line archosaurs. Beyond providing a comprehensive view of vertebral pneumaticity in a non-avian coelurosaur, this study demonstrates the utility and need of CT imaging for further clarifying the early evolutionary history of postcranial pneumaticity.
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Affiliation(s)
- Akinobu Watanabe
- Division of Paleontology, American Museum of Natural History, New York, New York, United States of America
- Richard Gilder Graduate School, American Museum of Natural History, New York, New York, United States of America
| | - Maria Eugenia Leone Gold
- Division of Paleontology, American Museum of Natural History, New York, New York, United States of America
- Richard Gilder Graduate School, American Museum of Natural History, New York, New York, United States of America
| | | | - Roger B. J. Benson
- Department of Earth Sciences, University of Oxford, Oxford, United Kingdom
- Evolutionary Studies Institute and DST/NRF Centre of Excellence in Palaeosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Jonah Choiniere
- Evolutionary Studies Institute and DST/NRF Centre of Excellence in Palaeosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Amy Davidson
- Division of Paleontology, American Museum of Natural History, New York, New York, United States of America
| | - Mark A. Norell
- Division of Paleontology, American Museum of Natural History, New York, New York, United States of America
- Richard Gilder Graduate School, American Museum of Natural History, New York, New York, United States of America
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13
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Martin-Silverstone E, Vincze O, McCann R, Jonsson CHW, Palmer C, Kaiser G, Dyke G. Exploring the Relationship between Skeletal Mass and Total Body Mass in Birds. PLoS One 2015; 10:e0141794. [PMID: 26509531 PMCID: PMC4625084 DOI: 10.1371/journal.pone.0141794] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 10/13/2015] [Indexed: 11/18/2022] Open
Abstract
Total body mass (TBM) is known to be related to a number of different osteological features in vertebrates, including limb element measurements and total skeletal mass. The relationship between skeletal mass and TBM in birds has been suggested as a way of estimating the latter in cases where only the skeleton is known (e.g., fossils). This relationship has thus also been applied to other extinct vertebrates, including the non-avian pterosaurs, while other studies have used additional skeletal correlates found in modern birds to estimate TBM. However, most previous studies have used TBM compiled from the literature rather than from direct measurements, producing values from population averages rather than from individuals. Here, we report a new dataset of 487 extant birds encompassing 79 species that have skeletal mass and TBM recorded at the time of collection or preparation. We combine both historical and new data for analyses with phylogenetic control and find a similar and well-correlated relationship between skeletal mass and TBM. Thus, we confirm that TBM and skeletal mass are accurate proxies for estimating one another. We also look at other factors that may have an effect on avian body mass, including sex, ontogenetic stage, and flight mode. While data are well-correlated in all cases, phylogeny is a major control on TBM in birds strongly suggesting that this relationship is not appropriate for estimating the total mass of taxa outside of crown birds, Neornithes (e.g., non-avian dinosaurs, pterosaurs). Data also reveal large variability in both bird skeletal and TBM within single species; caution should thus be applied when using published mass to test direct correlations with skeletal mass and bone lengths.
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Affiliation(s)
- Elizabeth Martin-Silverstone
- Ocean and Earth Sciences, University of Southampton, Southampton, Hampshire, United Kingdom
- School of Earth Sciences, University of Bristol, Bristol, United Kingdom
- * E-mail:
| | - Orsolya Vincze
- MTA-DE “Lendület” Behavioural Ecology Research Group, Department of Evolutionary Zoology, University of Debrecen, Debrecen, Hungary
- Faculty of Biology and Geology, Babes Bolyai University, Cluj Napoca, Romania
| | - Ria McCann
- Ocean and Earth Sciences, University of Southampton, Southampton, Hampshire, United Kingdom
| | | | - Colin Palmer
- School of Earth Sciences, University of Bristol, Bristol, United Kingdom
| | - Gary Kaiser
- Royal British Columbia Museum, Victoria, British Columbia, Canada
| | - Gareth Dyke
- Ocean and Earth Sciences, University of Southampton, Southampton, Hampshire, United Kingdom
- MTA-DE “Lendület” Behavioural Ecology Research Group, Department of Evolutionary Zoology, University of Debrecen, Debrecen, Hungary
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