1
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Schnetz L, Butler RJ, Coates MI, Sansom IJ. The skeletal completeness of the Palaeozoic chondrichthyan fossil record. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231451. [PMID: 38298400 PMCID: PMC10827434 DOI: 10.1098/rsos.231451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 01/08/2024] [Indexed: 02/02/2024]
Abstract
Chondrichthyes (sharks, rays, ratfish and their extinct relatives) originated and diversified in the Palaeozoic but are rarely preserved as articulated or partly articulated remains because of their predominantly cartilaginous endoskeletons. Consequently, their evolutionary history is perceived to be documented predominantly by isolated teeth, scales and fin spines. Here, we aim to capture and analyse the quality of the Palaeozoic chondrichthyan fossil record by using a variation of the skeletal completeness metric, which calculates how complete the skeletons of individuals are compared to estimates of their original entirety. Notably, chondrichthyan completeness is significantly lower than any published vertebrate group: low throughout the Silurian and Permian but peaking in the Devonian and Carboniferous. Scores increase to a range similar to pelycosaurs and parareptiles only when taxa identified solely from isolated teeth, scales and spines are excluded. We argue that environmental influences probably played an important role in chondrichthyan completeness. Sea level significantly negatively correlates with chondrichthyan completeness records and resembles patterns already evident in records of ichthyosaurs, plesiosaurs and sauropodomorphs. Such observed variations in completeness highlight the impact of different sampling biases on the chondrichthyan fossil record and the need to acknowledge these when inferring patterns of chondrichthyan macroevolution.
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Affiliation(s)
- Lisa Schnetz
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Richard J. Butler
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Michael I. Coates
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637-1508, USA
| | - Ivan J. Sansom
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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2
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Brownstein CD. Palaeospondylus and the early evolution of gnathostomes. Nature 2023; 620:E20-E22. [PMID: 37612401 DOI: 10.1038/s41586-023-06434-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 07/14/2023] [Indexed: 08/25/2023]
Affiliation(s)
- Chase Doran Brownstein
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA.
- Stamford Museum and Nature Center, Stamford, CT, USA.
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3
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Charest F, Mondéjar Fernández J, Grünbaum T, Cloutier R. Evolution of median fin patterning and modularity in living and fossil osteichthyans. PLoS One 2023; 18:e0272246. [PMID: 36921006 PMCID: PMC10016723 DOI: 10.1371/journal.pone.0272246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 02/24/2023] [Indexed: 03/16/2023] Open
Abstract
Morphological and developmental similarities, and interactions among developing structures are interpreted as evidences of modularity. Such similarities exist between the dorsal and anal fins of living actinopterygians, on the anteroposterior axis: (1) both fins differentiate in the same direction [dorsal and anal fin patterning module (DAFPM)], and (2) radials and lepidotrichia differentiate in the same direction [endoskeleton and exoskeleton module (EEM)]. To infer the evolution of these common developmental patternings among osteichthyans, we address (1) the complete description and quantification of the DAFPM and EEM in a living actinopterygian (the rainbow trout Oncorhynchus mykiss) and (2) the presence of these modules in fossil osteichthyans (coelacanths, lungfishes, porolepiforms and 'osteolepiforms'). In Oncorhynchus, sequences of skeletal elements are determined based on (1) apparition (radials and lepidotrichia), (2) chondrification (radials), (3) ossification (radials and lepidotrichia), and (4) segmentation plus bifurcation (lepidotrichia). Correlations are then explored between sequences. In fossil osteichthyans, sequences are determined based on (1) ossification (radials and lepidotrichia), (2) segmentation, and (3) bifurcation of lepidotrichia. Segmentation and bifurcation patterns were found crucial for comparisons between extant and extinct osteichthyan taxa. Our data suggest that the EEM is plesiomorphic at least for actinopterygians, and the DAFPM is plesiomorphic for osteichthyans, with homoplastic dissociation. Finally, recurrent patterns suggest the presence of a Lepidotrichia Patterning Module (LPM).
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Affiliation(s)
- France Charest
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, Rimouski, Québec, Canada
- Parc National de Miguasha, Nouvelle, Québec, Canada
| | - Jorge Mondéjar Fernández
- Senckenberg Forschungsinstitut und Naturmuseum Frankfurt, Frankfurt am Main, Germany
- Centre de Recherche en Paléontologie–Paris, Département Origines & Évolution, Muséum National d’Histoire Naturelle, UMR 7207 (MNHN–Sorbonne Université–CNRS), Paris, France
| | - Thomas Grünbaum
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, Rimouski, Québec, Canada
| | - Richard Cloutier
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, Rimouski, Québec, Canada
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4
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Greif M, Ferrón HG, Klug C. A new Meckel's cartilage from the Devonian Hangenberg black shale in Morocco and its position in chondrichthyan jaw morphospace. PeerJ 2022; 10:e14418. [PMID: 36573235 PMCID: PMC9789696 DOI: 10.7717/peerj.14418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 10/28/2022] [Indexed: 12/24/2022] Open
Abstract
Fossil chondrichthyan remains are mostly known from their teeth, scales or fin spines only, whereas their cartilaginous endoskeletons require exceptional preservational conditions to become fossilized. While most cartilaginous remains of Famennian (Late Devonian) chondrichthyans were found in older layers of the eastern Anti-Atlas, such fossils were unknown from the Hangenberg black shale (HBS) and only a few chondrichthyan teeth had been found therein previously. Here, we describe a Meckel's cartilage from the Hangenberg black shale in Morocco, which is the first fossil cartilage from these strata. Since no teeth or other skeletal elements have been found in articulation, we used elliptical Fourier (EFA), principal component (PCA), and hierarchical cluster (HCA) analyses to morphologically compare it with 41 chondrichthyan taxa of different size and age and to evaluate its possible systematic affiliation. PCA and HCA position the new specimen closest to some acanthodian and elasmobranch jaws. Accordingly, a holocephalan origin was excluded. The jaw shape as well as the presence of a polygonal pattern, typical for tessellated calcified cartilage, suggest a ctenacanth origin and we assigned the new HBS Meckel's cartilage to the order Ctenacanthiformes with reservations.
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Affiliation(s)
- Merle Greif
- Palaeontological Institute and Museum, University of Zürich, Zürich, Switzerland
| | - Humberto G. Ferrón
- Instituto Cavanilles de Biodiversidad i Biología Evolutiva, Universitat de València, Paterna, Valencia, Spain
| | - Christian Klug
- Palaeontological Institute and Museum, University of Zürich, Zürich, Switzerland
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5
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Berio F, Bayle Y, Riley C, Larouche O, Cloutier R. Phenotypic regionalization of the vertebral column in the thorny skate Amblyraja radiata: Stability and variation. J Anat 2022; 240:253-267. [PMID: 34542171 PMCID: PMC8742970 DOI: 10.1111/joa.13551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/03/2021] [Accepted: 09/06/2021] [Indexed: 01/14/2023] Open
Abstract
Regionalization of the vertebral column occurred early during vertebrate evolution and has been extensively investigated in mammals. However, less data are available on vertebral regions of crown gnathostomes. This is particularly true for batoids (skates, sawfishes, guitarfishes, and rays) whose vertebral column has long been considered to be composed of the same two regions as in teleost fishes despite the presence of a synarcual. However, the numerous vertebral units in chondrichthyans may display a more complex regionalization pattern than previously assumed and the intraspecific variation of such pattern deserves a thorough investigation. In this study, we use micro-computed tomography (µCT) scans of vertebral columns of a growth series of thorny skates Amblyraja radiata to provide the first fine-scale morphological description of vertebral units in a batoids species. We further investigate axial regionalization using a replicable clustering analysis on presence/absence of vertebral elements to decipher the regionalization of the vertebral column of A. radiata. We identify four vertebral regions in this species. The two anteriormost regions, named synarcual and thoracic, may undergo strong developmental or functional constraints because they display stable patterns of shapes and numbers of vertebral units across all growth stages. The third region, named hemal transitional, is characterized by high inter-individual morphological variation and displays a transition between the monospondylous (one centrum per somite) to diplospondylous (two centra per somite) conditions. The posteriormost region, named caudal, is subdivided into three sub-regions with shapes changing gradually along the anteroposterior axis. These regionalized patterns are discussed in light of ecological habits of skates.
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Affiliation(s)
- Fidji Berio
- Laboratoire de Paléontologie et Biologie ÉvolutiveUniversité du Québec à RimouskiRimouskiQuébecCanada
| | - Yann Bayle
- Université de BordeauxBordeaux INPCNRSLaBRIUMR5800TalenceFrance
| | - Cyrena Riley
- Laboratoire de Paléontologie et Biologie ÉvolutiveUniversité du Québec à RimouskiRimouskiQuébecCanada
| | - Olivier Larouche
- Laboratoire de Paléontologie et Biologie ÉvolutiveUniversité du Québec à RimouskiRimouskiQuébecCanada
- Department of BioSciencesRice UniversityHoustonTexasUSA
| | - Richard Cloutier
- Laboratoire de Paléontologie et Biologie ÉvolutiveUniversité du Québec à RimouskiRimouskiQuébecCanada
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6
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Rücklin M, King B, Cunningham JA, Johanson Z, Marone F, Donoghue PCJ. Acanthodian dental development and the origin of gnathostome dentitions. Nat Ecol Evol 2021; 5:919-926. [PMID: 33958756 DOI: 10.1038/s41559-021-01458-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 03/30/2021] [Indexed: 11/09/2022]
Abstract
Chondrichthyan dentitions are conventionally interpreted to reflect the ancestral gnathostome condition but interpretations of osteichthyan dental evolution in this light have proved unsuccessful, perhaps because chondrichthyan dentitions are equally specialized, or else evolved independently. Ischnacanthid acanthodians are stem-Chondrichthyes; as phylogenetic intermediates of osteichthyans and crown-chondrichthyans, the nature of their enigmatic dentition may inform homology and the ancestral gnathostome condition. Here we show that ischnacanthid marginal dentitions were statodont, composed of multicuspidate teeth added in distally diverging rows and through proximal superpositional replacement, while their symphyseal tooth whorls are comparable to chondrichthyan and osteichthyan counterparts. Ancestral state estimation indicates the presence of oral tubercles on the jaws of the gnathostome crown-ancestor; tooth whorls or tooth rows evolved independently in placoderms, osteichthyans, ischnacanthids, other acanthodians and crown-chondrichthyans. Crown-chondrichthyan dentitions are derived relative to the gnathostome crown-ancestor, which possessed a simple dentition and lacked a permanent dental lamina, which evolved independently in Chondrichthyes and Osteichthyes.
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Affiliation(s)
- Martin Rücklin
- Naturalis Biodiversity Center, Leiden, The Netherlands.
- School of Earth Sciences, University of Bristol, Life Sciences Building, Bristol, UK.
| | - Benedict King
- Naturalis Biodiversity Center, Leiden, The Netherlands
- Department of Linguistic and Cultural Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - John A Cunningham
- School of Earth Sciences, University of Bristol, Life Sciences Building, Bristol, UK
| | - Zerina Johanson
- Department of Earth Sciences, Natural History Museum, London, UK
| | - Federica Marone
- Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland
| | - Philip C J Donoghue
- School of Earth Sciences, University of Bristol, Life Sciences Building, Bristol, UK.
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7
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Maisey JG, Denton JSS, Burrow C, Pradel A. Architectural and ultrastructural features of tessellated calcified cartilage in modern and extinct chondrichthyan fishes. JOURNAL OF FISH BIOLOGY 2021; 98:919-941. [PMID: 32388865 DOI: 10.1111/jfb.14376] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 04/22/2020] [Accepted: 05/06/2020] [Indexed: 06/11/2023]
Abstract
Tessellated calcified cartilage (TCC) is a distinctive kind of biomineralized perichondral tissue found in many modern and extinct chondrichthyans (sharks, rays, chimaeroids and their extinct allies). Customarily, this feature has been treated somewhat superficially in phylogenetic analyses, often as a single "defining" character of a chondrichthyan clade. TCC is actually a complex hard tissue with numerous distinctive attributes, but its use as a character complex for phylogenetic analysis has not yet been optimized. This study attempts to improve this situation by presenting new terminology for certain aspects of tesseral architecture, including single-monolayered, multiple-monolayered, polylayered and voussoir tesserae; new histological data, including thin sections of TCC in several Palaeozoic taxa, and new proposals for ways in which various characters and states (many of which are defined here for the first time) could be applied in future phylogenetic analyses of chondrichthyan fishes. It can be concluded that many, but not all, of the unique attributes of modern TCC evolved by the Early Devonian (ca. 400 before present (bp)). The globular calcified cartilage reported in Silurian sinacanthids and the so-called subtessellated perichondral biomineralization (with irregular and ill-defined geometries of a layer or layers of calcified cartilage blocks) of certain extinct "acanthodians" (e.g., Climatius, Ischnacanthus, Cheiracanthus) could represent evolutionary precursors of TCC, which seems to characterize only part of the chondrichthyan total group. It is hypothesized that heavily biomineralized "layer-cake" TCC in certain Palaeozoic chondrichthyans perhaps served a dual physiological role, as a phosphate sink and in providing increased skeletal density in very large (>7 m) Devonian-Permian marine sharks such as ctenacanths and as an adaptation to calcium-deficient environments among Permo-Carboniferous non-marine sharks such as xenacanths. By contrast, the equivalent tissue in modern elasmobranchs probably serves only to reinforce regions of cartilage (mostly in the jaws) subjected to high loading. It is also noted that much of the variation observed in tesseral architecture (including localized remodelling), ultrastructure and histology in modern and extinct chondrichthyans is confined to the perichondrally facing cap zone (where Type-1 collagen matrix predominates in modern TCC), whereas the main body of the tessera (where Type-2 collagen matrix predominates) exhibits comparatively little evidence of remodelling and histological or structural variation.
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Affiliation(s)
- John G Maisey
- Department of Vertebrate Paleontology, American Museum of Natural History, New York City, New York, USA
| | - John S S Denton
- Florida Museum of Natural History, Gainesville, Florida, USA
| | - Carole Burrow
- Geosciences, Queensland Museum, Hendra, Queensland, Australia
| | - Alan Pradel
- Centre de Recherche en Paléontologie - Paris, Muséum National d'Histoire Naturelle, Sorbonne Université, Centre National de la Recherche Scientifique, Paris, France
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8
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Haridy Y, Osenberg M, Hilger A, Manke I, Davesne D, Witzmann F. Bone metabolism and evolutionary origin of osteocytes: Novel application of FIB-SEM tomography. SCIENCE ADVANCES 2021; 7:eabb9113. [PMID: 33789889 PMCID: PMC8011976 DOI: 10.1126/sciadv.abb9113] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 02/11/2021] [Indexed: 06/10/2023]
Abstract
Lacunae and canaliculi spaces of osteocytes are remarkably well preserved in fossilized bone and serve as an established proxy for bone cells. The earliest bone in the fossil record is acellular (anosteocytic), followed by cellular (osteocytic) bone in the jawless relatives of jawed vertebrates, the osteostracans, about 400 million years ago. Virtually nothing is known about the physiological pressures that would have initially favored osteocytic over anosteocytic bone. We apply focused ion beam-scanning electron microscopy tomography combined with machine learning for cell detection and segmentation to image fossil cell spaces. Novel three-dimensional high-resolution images reveal areas of low density around osteocyte lacunae and their canaliculi in osteostracan bone. This provides evidence for demineralization that would have occurred in vivo as part of osteocytic osteolysis, a mechanism of mineral homeostasis, supporting the hypothesis that a physiological demand for phosphorus was the principal driver in the initial evolution of osteocytic bone.
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Affiliation(s)
- Yara Haridy
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany.
| | - Markus Osenberg
- Helmholtz Centre for Materials and Energy (HZB), Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - André Hilger
- Helmholtz Centre for Materials and Energy (HZB), Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Ingo Manke
- Helmholtz Centre for Materials and Energy (HZB), Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Donald Davesne
- Department of Earth Sciences, University of Oxford, OX1 3AN Oxford, UK
- Institut de Systématique, Évolution, Biodiversité (UMR 7205), Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, 75005 Paris, France
| | - Florian Witzmann
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
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9
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McKenna KZ, Wagner GP, Cooper KL. A developmental perspective of homology and evolutionary novelty. Curr Top Dev Biol 2021; 141:1-38. [PMID: 33602485 DOI: 10.1016/bs.ctdb.2020.12.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The development and evolution of multicellular body plans is complex. Many distinct organs and body parts must be reproduced at each generation, and those that are traceable over long time scales are considered homologous. Among the most pressing and least understood phenomena in evolutionary biology is the mode by which new homologs, or "novelties" are introduced to the body plan and whether the developmental changes associated with such evolution deserve special treatment. In this chapter, we address the concepts of homology and evolutionary novelty through the lens of development. We present a series of case studies, within insects and vertebrates, from which we propose a developmental model of multicellular organ identity. With this model in hand, we make predictions regarding the developmental evolution of body plans and highlight the need for more integrative analysis of developing systems.
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Affiliation(s)
- Kenneth Z McKenna
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, United States
| | - Günter P Wagner
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, United States.
| | - Kimberly L Cooper
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, United States
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10
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Ferrón HG, Martínez-Pérez C, Rahman IA, Selles de Lucas V, Botella H, Donoghue PCJ. Functional assessment of morphological homoplasy in stem-gnathostomes. Proc Biol Sci 2021; 288:20202719. [PMID: 33467997 PMCID: PMC7893270 DOI: 10.1098/rspb.2020.2719] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/22/2020] [Indexed: 11/12/2022] Open
Abstract
Osteostraci and Galeaspida are stem-gnathostomes, occupying a key phylogenetic position for resolving the nature of the jawless ancestor from which jawed vertebrates evolved more than 400 million years ago. Both groups are characterized by the presence of rigid headshields that share a number of common morphological traits, in some cases hindering the resolution of their interrelationships and the exact nature of their affinities with jawed vertebrates. Here, we explore the morphological and functional diversity of osteostracan and galeaspid headshields using geometric morphometrics and computational fluid dynamics to constrain the factors that promoted the evolution of their similar morphologies and informing on the ecological scenario under which jawed vertebrates emerged. Phylomorphospace, Mantel analysis and Stayton metrics demonstrate a high degree of homoplasy. Computational fluid dynamics reveals similar hydrodynamic performance among morphologically convergent species, indicating the independent acquisition of the same morphofunctional traits and, potentially, equivalent lifestyles. These results confirm that a number of the characters typically used to infer the evolutionary relationships among galeaspids, osteostracans and jawed vertebrates are convergent in nature, potentially obscuring understanding of the assembly of the gnathostome bodyplan. Ultimately, our results reveal that while the jawless relatives of the earliest jawed vertebrates were ecologically diverse, widespread convergence on the same hydrodynamic adaptations suggests they had reached the limits of their potential ecological diversity-overcome by jawed vertebrates and their later innovations.
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Affiliation(s)
- Humberto G. Ferrón
- School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK
- Instituto Cavanilles de Biodiversidad i Biología Evolutiva, Universitat de València, C/ Catedrático José Beltrán Martínez, 2, 46980 Paterna, Valencia, Spain
| | - Carlos Martínez-Pérez
- School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK
- Instituto Cavanilles de Biodiversidad i Biología Evolutiva, Universitat de València, C/ Catedrático José Beltrán Martínez, 2, 46980 Paterna, Valencia, Spain
| | - Imran A. Rahman
- Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, UK
| | - Víctor Selles de Lucas
- School of Engineering and Computer Science, University of Hull, Cottingham Rd, Hull HU6 7RX, UK
| | - Héctor Botella
- Instituto Cavanilles de Biodiversidad i Biología Evolutiva, Universitat de València, C/ Catedrático José Beltrán Martínez, 2, 46980 Paterna, Valencia, Spain
| | - Philip C. J. Donoghue
- School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK
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11
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King B, Rücklin M. A Bayesian approach to dynamic homology of morphological characters and the ancestral phenotype of jawed vertebrates. eLife 2020; 9:e62374. [PMID: 33274719 PMCID: PMC7793628 DOI: 10.7554/elife.62374] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 12/03/2020] [Indexed: 12/22/2022] Open
Abstract
Phylogenetic analysis of morphological data proceeds from a fixed set of primary homology statements, the character-by-taxon matrix. However, there are cases where multiple conflicting homology statements can be justified from comparative anatomy. The upper jaw bones of placoderms have traditionally been considered homologous to the palatal vomer-dermopalatine series of osteichthyans. The discovery of 'maxillate' placoderms led to the alternative hypothesis that 'core' placoderm jaw bones are premaxillae and maxillae lacking external (facial) laminae. We introduce a BEAST2 package for simultaneous inference of homology and phylogeny, and find strong evidence for the latter hypothesis. Phenetic analysis of reconstructed ancestors suggests that maxillate placoderms are the most plesiomorphic known gnathostomes, and the shared cranial architecture of arthrodire placoderms, maxillate placoderms and osteichthyans is inherited. We suggest that the gnathostome ancestor possessed maxillae and premaxillae with facial and palatal laminae, and that these bones underwent divergent evolutionary trajectories in placoderms and osteichthyans.
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12
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Seidel R, Blumer M, Chaumel J, Amini S, Dean MN. Endoskeletal mineralization in chimaera and a comparative guide to tessellated cartilage in chondrichthyan fishes (sharks, rays and chimaera). J R Soc Interface 2020; 17:20200474. [PMID: 33050779 PMCID: PMC7653374 DOI: 10.1098/rsif.2020.0474] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
An accepted uniting character of modern cartilaginous fishes (sharks, rays, chimaera) is the presence of a mineralized, skeletal crust, tiled by numerous minute plates called tesserae. Tesserae have, however, never been demonstrated in modern chimaera and it is debated whether the skeleton mineralizes at all. We show for the first time that tessellated cartilage was not lost in chimaera, as has been previously postulated, and is in many ways similar to that of sharks and rays. Tesserae in Chimaera monstrosa are less regular in shape and size in comparison to the general scheme of polygonal tesserae in sharks and rays, yet share several features with them. For example, Chimaera tesserae, like those of elasmobranchs, possess both intertesseral joints (unmineralized regions, where fibrous tissue links adjacent tesserae) and recurring patterns of local mineral density variation (e.g. Liesegang lines, hypermineralized ‘spokes’), reflecting periodic accretion of mineral at tesseral edges as tesserae grow. Chimaera monstrosa's tesserae, however, appear to lack the internal cell networks that characterize tesserae in elasmobranchs, indicating fundamental differences among chondrichthyan groups in how calcification is controlled. By compiling and comparing recent ultrastructure data on tesserae, we also provide a synthesized, up-to-date and comparative glossary on tessellated cartilage, as well as a perspective on the current state of research into the topic, offering benchmark context for future research into modern and extinct vertebrate skeletal tissues.
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Affiliation(s)
- Ronald Seidel
- B CUBE-Center for Molecular Bioengineering, Technical University Dresden, 01307 Dresden, Germany.,Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, 14424 Potsdam, Germany
| | - Michael Blumer
- Medical University Innsbruck, Division of Clinical and Functional Anatomy, 6020 Innsbruck, Austria
| | - Júlia Chaumel
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, 14424 Potsdam, Germany
| | - Shahrouz Amini
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, 14424 Potsdam, Germany
| | - Mason N Dean
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, 14424 Potsdam, Germany
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13
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Endochondral bone in an Early Devonian 'placoderm' from Mongolia. Nat Ecol Evol 2020; 4:1477-1484. [PMID: 32895518 DOI: 10.1038/s41559-020-01290-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 07/23/2020] [Indexed: 11/08/2022]
Abstract
Endochondral bone is the main internal skeletal tissue of nearly all osteichthyans-the group comprising more than 60,000 living species of bony fishes and tetrapods. Chondrichthyans (sharks and their kin) are the living sister group of osteichthyans and have primarily cartilaginous endoskeletons, long considered the ancestral condition for all jawed vertebrates (gnathostomes). The absence of bone in modern jawless fishes and the absence of endochondral ossification in early fossil gnathostomes appear to lend support to this conclusion. Here we report the discovery of extensive endochondral bone in Minjinia turgenensis, a new genus and species of 'placoderm'-like fish from the Early Devonian (Pragian) of western Mongolia described using X-ray computed microtomography. The fossil consists of a partial skull roof and braincase with anatomical details providing strong evidence of placement in the gnathostome stem group. However, its endochondral space is filled with an extensive network of fine trabeculae resembling the endochondral bone of osteichthyans. Phylogenetic analyses place this new taxon as a proximate sister group of the gnathostome crown. These results provide direct support for theories of generalized bone loss in chondrichthyans. Furthermore, they revive theories of a phylogenetically deeper origin of endochondral bone and its absence in chondrichthyans as a secondary condition.
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York JR, Yuan T, McCauley DW. Evolutionary and Developmental Associations of Neural Crest and Placodes in the Vertebrate Head: Insights From Jawless Vertebrates. Front Physiol 2020; 11:986. [PMID: 32903576 PMCID: PMC7438564 DOI: 10.3389/fphys.2020.00986] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 07/20/2020] [Indexed: 12/12/2022] Open
Abstract
Neural crest and placodes are key innovations of the vertebrate clade. These cells arise within the dorsal ectoderm of all vertebrate embryos and have the developmental potential to form many of the morphological novelties within the vertebrate head. Each cell population has its own distinct developmental features and generates unique cell types. However, it is essential that neural crest and placodes associate together throughout embryonic development to coordinate the emergence of several features in the head, including almost all of the cranial peripheral sensory nervous system and organs of special sense. Despite the significance of this developmental feat, its evolutionary origins have remained unclear, owing largely to the fact that there has been little comparative (evolutionary) work done on this topic between the jawed vertebrates and cyclostomes—the jawless lampreys and hagfishes. In this review, we briefly summarize the developmental mechanisms and genetics of neural crest and placodes in both jawed and jawless vertebrates. We then discuss recent studies on the role of neural crest and placodes—and their developmental association—in the head of lamprey embryos, and how comparisons with jawed vertebrates can provide insights into the causes and consequences of this event in early vertebrate evolution.
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Affiliation(s)
- Joshua R York
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Tian Yuan
- Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - David W McCauley
- Department of Biology, University of Oklahoma, Norman, OK, United States
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15
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Johanson Z, Manzanares E, Underwood C, Clark B, Fernandez V, Smith M. Evolution of the Dentition in Holocephalans (Chondrichthyes) Through Tissue Disparity. Integr Comp Biol 2020; 60:630-643. [DOI: 10.1093/icb/icaa093] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
The Holocephali is a major group of chondrichthyan fishes, the sister taxon to the sharks and rays (Elasmobranchii). However, the dentition of extant holocephalans is very different from that of the elasmobranchs, lacking individual tooth renewal, but comprising dental plates made entirely of self-renewing dentine. This renewal of all tissues occurs at the postero-lingual plate surface, as a function of their statodont condition. The fossil record of the holocephalans illuminates multiple different trends in the dentition, including shark-like teeth through to those with dentitions completely lacking individual teeth. Different taxa illustrate developmental retention of teeth but with fusion in their serial development. Dentine of different varieties comprises these teeth and composite dental plates, whose histology includes vascularized tubes within coronal dentine, merging with basal trabecular dentine. In this coronal vascularized dentine, extensive hypermineralization forms a wear resistant tissue transformed into a variety of morphologies. Through evolution, hypermineralized dentine becomes enclosed within the trabecular dentine, and specialized by reduction into specific zones within a composite dental plate, with these increasing in morphological disparity, all reflecting loss of defined teeth but retention of dentine production from the inherited developmental package.
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Affiliation(s)
- Zerina Johanson
- Department of Earth Sciences, Natural History Museum, London, UK
| | - Esther Manzanares
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de Valencia, Paterna, Valencia 46980, Spain
| | - Charlie Underwood
- Department of Earth Sciences, Natural History Museum, London, UK
- Department of Earth and Planetary Sciences, Birkbeck, University of London, London, UK
| | - Brett Clark
- Core Research Laboratories, Natural History Museum, London, UK
| | | | - Moya Smith
- Department of Earth Sciences, Natural History Museum, London, UK
- Centre for Craniofacial and Regenerative Biology, Oral and Craniofacial Sciences, King’s College London, London, UK
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16
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Diogo R. Cranial or postcranial—Dual origin of the pectoral appendage of vertebrates combining the fin‐fold and gill‐arch theories? Dev Dyn 2020; 249:1182-1200. [DOI: 10.1002/dvdy.192] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/22/2020] [Accepted: 05/05/2020] [Indexed: 11/10/2022] Open
Affiliation(s)
- Rui Diogo
- Department of Anatomy Howard University College of Medicine Washington District of Columbia USA
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Schnetz L, Pfaff C, Libowitzky E, Johanson Z, Stepanek R, Kriwet J. Morphology and evolutionary significance of phosphatic otoliths within the inner ears of cartilaginous fishes (Chondrichthyes). BMC Evol Biol 2019; 19:238. [PMID: 31888446 PMCID: PMC6937729 DOI: 10.1186/s12862-019-1568-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 12/17/2019] [Indexed: 12/02/2022] Open
Abstract
Background Chondrichthyans represent a monophyletic group of crown group gnathostomes and are central to our understanding of vertebrate evolution. Like all vertebrates, cartilaginous fishes evolved concretions of material within their inner ears to aid with equilibrium and balance detection. Up to now, these materials have been identified as calcium carbonate-bearing otoconia, which are small bio-crystals consisting of an inorganic mineral and a protein, or otoconial masses (aggregations of otoconia bound by an organic matrix), being significantly different in morphology compared to the singular, polycrystalline otolith structures of bony fishes, which are solidified bio-crystals forming stony masses. Reinvestigation of the morphological and chemical properties of these chondrichthyan otoconia revises our understanding of otolith composition and has implications on the evolution of these characters in both the gnathostome crown group, and cartilaginous fishes in particular. Results Dissections of Amblyraja radiata, Potamotrygon leopoldi, and Scyliorhinus canicula revealed three pairs of singular polycrystalline otolith structures with a well-defined morphology within their inner ears, as observed in bony fishes. IR spectroscopy identified the material to be composed of carbonate/collagen-bearing apatite in all taxa. These findings contradict previous hypotheses suggesting these otoconial structures were composed of calcium carbonate in chondrichthyans. A phylogenetic mapping using 37 chondrichthyan taxa further showed that the acquisition of phosphatic otolith structures might be widespread within cartilaginous fishes. Conclusions Differences in the size and shape of otoliths between taxa indicate a taxonomic signal within elasmobranchs. Otoliths made of carbonate/collagen-bearing apatite are reported for the first time in chondrichthyans. The intrinsic pathways to form singular, polycrystalline otoliths may represent the plesiomorphic condition for vertebrates but needs further testing. Likewise, the phosphatic composition of otoliths in early vertebrates such as cyclostomes and elasmobranchs is probably closely related to the lack of bony tissue in these groups, supporting a close relationship between skeletal tissue mineralization patterns and chemical otolith composition, underlined by physiological constraints.
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Affiliation(s)
- Lisa Schnetz
- University of Birmingham, School of Geography, Earth and Environmental Sciences, Birmingham, B15 2TT, UK.
| | - Cathrin Pfaff
- University of Vienna, Faculty of Earth Sciences, Geography and Astronomy, Institute of Palaeontology, Geozentrum, Althanstraße 14, 1090, Vienna, Austria
| | - Eugen Libowitzky
- University of Vienna, Faculty of Earth Sciences, Geography and Astronomy, Institute of Mineralogy and Crystallography, Geozentrum, Althanstraße 14, 1090, Vienna, Austria
| | - Zerina Johanson
- Department of Earth Sciences, Natural History Museum, London, SW7 5BD, UK
| | - Rica Stepanek
- University of Vienna, Faculty of Earth Sciences, Geography and Astronomy, Institute of Palaeontology, Geozentrum, Althanstraße 14, 1090, Vienna, Austria
| | - Jürgen Kriwet
- University of Vienna, Faculty of Earth Sciences, Geography and Astronomy, Institute of Palaeontology, Geozentrum, Althanstraße 14, 1090, Vienna, Austria.
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Zhu YA, Lu J, Zhu M. Reappraisal of the Silurian placoderm Silurolepis and insights into the dermal neck joint evolution. ROYAL SOCIETY OPEN SCIENCE 2019; 6:191181. [PMID: 31598327 PMCID: PMC6774982 DOI: 10.1098/rsos.191181] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 08/20/2019] [Indexed: 05/15/2023]
Abstract
Silurolepis platydorsalis, a Silurian jawed vertebrate originally identified as an antiarch, is here redescribed as a maxillate placoderm close to Qilinyu and is anteroposteriorly reversed as opposed to the original description. The cuboid trunk shield possesses three longitudinal cristae, obstanic grooves on the trunk shield and three median dorsal plates, all uniquely shared with Qilinyu. Further preparation reveals the morphology of the dermal neck joint, with slot-shaped articular fossae on the trunk shield similar to Qilinyu and antiarchs. However, new tomographic data reveal that Qilinyu uniquely bears a dual articulation between the skull roof and trunk shield, which does not fit into the traditional 'ginglymoid' and 'reverse ginglymoid' categories. An extended comparison in early jawed vertebrates confirms that a sliding-type dermal neck joint is widely distributed and other types are elaborated in different lineages by developing various laminae. Nine new characters related to the dermal neck joint are proposed for a new phylogenetic analysis, in which Silurolepis forms a clade with Qilinyu. The current phylogenetic framework conflicts with the parsimonious evolution of dermal neck joints in suggesting that the shared trunk shield characters between antiarchs and Qilinyu are independently acquired, and the sliding-type joint in Entelognathus is reversely evolved from the dual articulation in Qilinyu.
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Affiliation(s)
- You-an Zhu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences (CAS), 142 Xi-zhi-men-wai Street, Beijing 100044, People's Republic of China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, People's Republic of China
- Subdepartment of Evolution and Development, Uppsala University, Norbyvägen 18A, 752 36 Uppsala, Sweden
| | - Jing Lu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences (CAS), 142 Xi-zhi-men-wai Street, Beijing 100044, People's Republic of China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, People's Republic of China
| | - Min Zhu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences (CAS), 142 Xi-zhi-men-wai Street, Beijing 100044, People's Republic of China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, People's Republic of China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Author for correspondence: Min Zhu e-mail:
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Davesne D, Meunier FJ, Schmitt AD, Friedman M, Otero O, Benson RBJ. The phylogenetic origin and evolution of acellular bone in teleost fishes: insights into osteocyte function in bone metabolism. Biol Rev Camb Philos Soc 2019; 94:1338-1363. [DOI: 10.1111/brv.12505] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 02/11/2019] [Accepted: 02/13/2019] [Indexed: 12/13/2022]
Affiliation(s)
- Donald Davesne
- Department of Earth SciencesUniversity of Oxford OX1 3AN Oxford U.K
| | - François J. Meunier
- BOREA (UMR 7208 CNRS, IRD, MNHN, Sorbonne Université)Muséum national d'Histoire naturelle 75005 Paris France
| | - Armin D. Schmitt
- Department of Earth SciencesUniversity of Oxford OX1 3AN Oxford U.K
| | - Matt Friedman
- Museum of Paleontology and Department of Earth and Environmental SciencesUniversity of Michigan Ann Arbor MI 48109‐1079 U.S.A
| | - Olga Otero
- PalEvoPrim (UMR 7262 CNRS)Université de Poitiers 86000 Poitiers France
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Coates MI, Finarelli JA, Sansom IJ, Andreev PS, Criswell KE, Tietjen K, Rivers ML, La Riviere PJ. An early chondrichthyan and the evolutionary assembly of a shark body plan. Proc Biol Sci 2019; 285:rspb.2017.2418. [PMID: 29298937 DOI: 10.1098/rspb.2017.2418] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 11/29/2017] [Indexed: 11/12/2022] Open
Abstract
Although relationships among the major groups of living gnathostomes are well established, the relatedness of early jawed vertebrates to modern clades is intensely debated. Here, we provide a new description of Gladbachus, a Middle Devonian (Givetian approx. 385-million-year-old) stem chondrichthyan from Germany, and one of the very few early chondrichthyans in which substantial portions of the endoskeleton are preserved. Tomographic and histological techniques reveal new details of the gill skeleton, hyoid arch and jaws, neurocranium, cartilage, scales and teeth. Despite many features resembling placoderm or osteichthyan conditions, phylogenetic analysis confirms Gladbachus as a stem chondrichthyan and corroborates hypotheses that all acanthodians are stem chondrichthyans. The unfamiliar character combination displayed by Gladbachus, alongside conditions observed in acanthodians, implies that pre-Devonian stem chondrichthyans are severely under-sampled and strongly supports indications from isolated scales that the gnathostome crown group originated at the latest by the early Silurian (approx. 440 Ma). Moreover, phylogenetic results highlight the likely convergent evolution of conventional chondrichthyan conditions among earliest members of this primary gnathostome division, while skeletal morphology points towards the likely suspension feeding habits of Gladbachus, suggesting a functional origin of the gill slit condition characteristic of the vast majority of living and fossil chondrichthyans.
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Affiliation(s)
- Michael I Coates
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637-1508, USA
| | - John A Finarelli
- UCD School of Biology and Environmental Science, UCD Science Education and Research Centre (West), UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Ivan J Sansom
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Plamen S Andreev
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Katharine E Criswell
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637-1508, USA.,Department of Zoology, Cambridge University, Cambridge CB2 3EJ, UK
| | - Kristen Tietjen
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637-1508, USA
| | - Mark L Rivers
- Center for Advanced Radiation Sources, University of Chicago, Chicago, IL 60637-1508, USA
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King B, Young GC, Long JA. New information on Brindabellaspis stensioi Young, 1980, highlights morphological disparity in Early Devonian placoderms. ROYAL SOCIETY OPEN SCIENCE 2018; 5:180094. [PMID: 30110452 PMCID: PMC6030278 DOI: 10.1098/rsos.180094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 04/26/2018] [Indexed: 06/08/2023]
Abstract
Acid-prepared specimens of the placoderm Brindabellaspis stensioi (Early Devonian of New South Wales, Australia) revealed placoderm endocranial anatomy in unprecedented detail. Brindabellaspis has become a key taxon in discussions of early gnathostome phylogeny, and the question of placoderm monophyly versus paraphyly. The anterior orientation of the facial nerve and related hyoid arch structures in this taxon resemble fossil osteostracans (jawless vertebrates) rather than other early gnathostomes. New specimens of Brindabellaspis now reveal the previously unknown anterior region of the skull, including an exceptionally elongate premedian bone forming a long rostrum, supported by a thin extension of the postethmo-occipital unit of the braincase. Lateral overlap surfaces indicate an unusual anterior position for the jaws. Digital rendering of a synchrotron radiation scan reveals a uniquely specialized ethmoid commissure sensory canal, doubled back and fused into a midline canal. The visceral surface of the premedian bone has a plexus of perichondral bone canals. An updated skull roof reconstruction of Brindabellaspis adds to the highly variable dermal skull patterns of the probably non-monophyletic 'acanthothoracids'. The unusual morphology revealed by the new specimens suggests that the earliest known reef fish fauna contained a diverse range of fishes with specialized ecological roles.
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Affiliation(s)
- Benedict King
- College of Science and Engineering, Flinders University, PO Box 2100, Adelaide, South Australia 5001, Australia
- Naturalis Biodiversity Center, Postbus 9517, 2300 RA Leiden, The Netherlands
| | - Gavin C. Young
- Research School of Physics and Engineering (RSPE), Australian National University, Canberra 0200, Australian Capital Territory, Australia
- Australian Museum Research Institute, 1 Williams Street, Sydney New South Wales 2010, Australia
| | - John A. Long
- College of Science and Engineering, Flinders University, PO Box 2100, Adelaide, South Australia 5001, Australia
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22
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Wang Y, Zhu M. Redescription of Phymolepis cuifengshanensis (Antiarcha: Yunnanolepididae) using high-resolution computed tomography and new insights into anatomical details of the endocranium in antiarchs. PeerJ 2018; 6:e4808. [PMID: 29868260 PMCID: PMC5978403 DOI: 10.7717/peerj.4808] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 04/30/2018] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Yunnanolepidoids constitute either the most basal consecutive segments or the most primitive clade of antiarchs, a highly diversified jawed vertebrate group from the Silurian and Early Devonian periods. Although the general morphology of yunnanolepidoids is well established, their endocranial features remain largely unclear, thus hindering our further understanding of antiarch evolution, and early gnathostome evolution. Phymolepis cuifengshanensis, a yunnanolepidoid from the Early Devonian of southwestern China, is re-described in detail to reveal the information on endocranial anatomy and additional morphological data of head and trunk shields. METHODS We scanned the material of P. cuifengshanensis using high-resolution computed tomography and generated virtual restorations to show the internal morphology of its dermal shield. The dorsal aspect of endocranium in P. cuifengshanensis was therefore inferred. The phylogenetic analysis of antiarchs was conducted based on a revised and expanded dataset that incorporates 10 new cranial characters. RESULTS The lateroventral fossa of trunk shield and Chang's apparatus are three-dimensionally restored in P. cuifengshanensis. The canal that is positioned just anterior to the internal cavity of Chang's apparatus probably corresponds to the rostrocaudal canal of euantiarchs. The endocranial morphology of P. cuifengshanensis corroborates a general pattern for yunnanolepidoids with additional characters distinguishing them from sinolepids and euantiarchs, such as a developed cranio-spinal process, an elongated endolymphatic duct, and a long occipital portion. DISCUSSION In light of new data from Phymolepis and Yunnanolepis, we summarized the morphology on the visceral surface of head shield in antiarchs, and formulated an additional 10 characters for the phylogenetic analysis. These cranial characters exhibit a high degree of morphological disparity between major subgroups of antiarchs, and highlight the endocranial character evolution in antiarchs.
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Affiliation(s)
- Yajing Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Min Zhu
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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Castiello M, Brazeau MD. Neurocranial anatomy of the petalichthyid placoderm Shearsbyaspis oepiki Young revealed by X-ray computed microtomography. PALAEONTOLOGY 2018; 61:369-389. [PMID: 29937580 PMCID: PMC5993267 DOI: 10.1111/pala.12345] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 11/20/2017] [Indexed: 06/08/2023]
Abstract
Stem-group gnathostomes reveal the sequence of character acquisition in the origin of modern jawed vertebrates. The petalichthyids are placoderm-grade stem-group gnathostomes known from both isolated skeletal material and rarer articulated specimens of one genus. They are of particular interest because of anatomical resemblances with osteostracans, the jawless sister group of jawed vertebrates. Because of this, they have become central to debates on the relationships of placoderms and the primitive cranial architecture of gnathostomes. However, among petalichthyids, only the braincase of Macropetalichthys has been studied in detail, and the diversity of neurocranial morphology in this group remains poorly documented. Using X-ray computed microtomography, we investigated the endocranial morphology of Shearsbyaspis oepiki Young, a three-dimensionally preserved petalichthyid from the Early Devonian of Taemas-Wee Jasper, Australia. We generated virtual reconstructions of the external endocranial surfaces, orbital walls and cranial endocavity, including canals for major nerves and blood vessels. The neurocranium of Shearsbyaspis resembles that of Macropetalichthys, particularly in the morphology of the brain cavity, nerves and blood vessels. Many characters, including the morphology of the pituitary vein canal and the course of the trigeminal nerve, recall the morphology of osteostracans. Additionally, the presence of a parasphenoid in Shearsbyaspis (previously not known with confidence outside of arthrodires and osteichthyans) raises some questions about current proposals of placoderm paraphyly. Our detailed description of this specimen adds to the known morphological diversity of petalichthyids, and invites critical reappraisal of the phylogenetic relationships of placoderms.
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Affiliation(s)
- Marco Castiello
- Department of Life Sciences Imperial College London Silwood Campus, Buckhurst Road Ascot SL5 7PY UK
| | - Martin D Brazeau
- Department of Life Sciences Imperial College London Silwood Campus, Buckhurst Road Ascot SL5 7PY UK
- Department of Earth Sciences Natural History Museum London SW7 5BD UK
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Smith KT, Bhullar BAS, Köhler G, Habersetzer J. The Only Known Jawed Vertebrate with Four Eyes and the Bauplan of the Pineal Complex. Curr Biol 2018; 28:1101-1107.e2. [PMID: 29614279 DOI: 10.1016/j.cub.2018.02.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 12/22/2017] [Accepted: 02/13/2018] [Indexed: 11/29/2022]
Abstract
The pineal and parapineal organs are dorsal outpocketings of the vertebrate diencephalon that play key roles in orientation and in circadian and annual cycles. Lampreys are four eyed in that both the pineal and parapineal form eyelike photosensory structures, but the pineal is the dominant or sole median photosensory structure in most lower vertebrate clades. The pineal complex has been thought to evolve in a single direction by losing photosensory and augmenting secretory function in the transitions from three-eyed lower vertebrates to two-eyed mammals and archosaurs [1-3]. Yet the widely accepted elaboration of the parapineal instead of the pineal as the primary median photosensory organ [4] in Lepidosauria (lizards, snakes, and tuataras) hints at a more complex evolutionary history. Here we present evidence that a fourth eye re-evolved from the pineal organ at least once within vertebrates, specifically in an extinct monitor lizard, Saniwa ensidens, in which pineal and parapineal eyes were present simultaneously. The tandem midline location of these structures confirms in a striking fashion the proposed homology of the parietal eye with the parapineal organ and refutes the classical model of pineal bilaterality. It furthermore raises questions about the evolution and functional interpretation of the median photosensory organ in other tetrapod clades.
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Affiliation(s)
- Krister T Smith
- Department of Messel Research and Mammalogy, Senckenberg Research Institute, Senckenberganlage 25, 60325 Frankfurt am Main, Germany; Department of Geology and Geophysics and Peabody Museum of Natural History, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA.
| | - Bhart-Anjan S Bhullar
- Department of Geology and Geophysics and Peabody Museum of Natural History, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA
| | - Gunther Köhler
- Section of Herpetology, Senckenberg Research Institute, Senckenberganlage 25, 60325 Frankfurt am Main, Germany
| | - Jörg Habersetzer
- Department of Messel Research and Mammalogy, Senckenberg Research Institute, Senckenberganlage 25, 60325 Frankfurt am Main, Germany
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King B, Qiao T, Lee MSY, Zhu M, Long JA. Bayesian Morphological Clock Methods Resurrect Placoderm Monophyly and Reveal Rapid Early Evolution in Jawed Vertebrates. Syst Biol 2018; 66:499-516. [PMID: 27920231 DOI: 10.1093/sysbio/syw107] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 11/18/2016] [Indexed: 11/13/2022] Open
Abstract
The phylogeny of early gnathostomes provides an important framework for understanding one of the most significant evolutionary events, the origin and diversification of jawed vertebrates. A series of recent cladistic analyses have suggested that the placoderms, an extinct group of armoured fish, form a paraphyletic group basal to all other jawed vertebrates. We revised and expanded this morphological data set, most notably by sampling autapomorphies in a similar way to parsimony-informative traits, thus ensuring this data (unlike most existing morphological data sets) satisfied an important assumption of Bayesian tip-dated morphological clock approaches. We also found problems with characters supporting placoderm paraphyly, including character correlation and incorrect codings. Analysis of this data set reveals that paraphyly and monophyly of core placoderms (excluding maxillate forms) are essentially equally parsimonious. The two alternative topologies have different root positions for the jawed vertebrates but are otherwise similar. However, analysis using tip-dated clock methods reveals strong support for placoderm monophyly, due to this analysis favoring trees with more balanced rates of evolution. Furthermore, enforcing placoderm paraphyly results in higher levels and unusual patterns of rate heterogeneity among branches, similar to that generated from simulated trees reconstructed with incorrect root positions. These simulations also show that Bayesian tip-dated clock methods outperform parsimony when the outgroup is largely uninformative (e.g., due to inapplicable characters), as might be the case here. The analysis also reveals that gnathostomes underwent a rapid burst of evolution during the Silurian period which declined during the Early Devonian. This rapid evolution during a period with few articulated fossils might partly explain the difficulty in ascertaining the root position of jawed vertebrates.
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Affiliation(s)
- Benedict King
- School of Biological Sciences, Flinders University, PO Box 2100, Adelaide, South Australia 5001, Australia
| | - Tuo Qiao
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, PO Box 643, Beijing 100044, China
| | - Michael S Y Lee
- School of Biological Sciences, Flinders University, PO Box 2100, Adelaide, South Australia 5001, Australia.,Earth Sciences Section, South Australian Museum, North Terrace, Adelaide 5000, Australia
| | - Min Zhu
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, PO Box 643, Beijing 100044, China
| | - John A Long
- School of Biological Sciences, Flinders University, PO Box 2100, Adelaide, South Australia 5001, Australia
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26
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Jerve A, Qu Q, Sanchez S, Ahlberg PE, Haitina T. Vascularization and odontode structure of a dorsal ridge spine of Romundina stellina Ørvig 1975. PLoS One 2017; 12:e0189833. [PMID: 29281687 PMCID: PMC5744956 DOI: 10.1371/journal.pone.0189833] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Accepted: 12/01/2017] [Indexed: 11/18/2022] Open
Abstract
There are two types of dermal skeletons in jawed vertebrates: placoderms and osteichthyans carry large bony plates (macromery), whereas chondrichthyans and acanthodians are covered by small scales (micromery). Fin spines are one of the last large dermal structures found on micromeric taxa and offer a potential source of histology and morphology that can be compared to those found on macromeric groups. Dermal fin spines offer a variety of morphology but aspects of their growth modes and homology are unclear. Here, we provide detailed descriptions of the microstructure and growth of a dorsal ridge spine from the acanthothoracid placoderm, Romundina stellina, using virtual three-dimensional paleohistological datasets. From these data we identify several layers of dentine ornamentation covering the lateral surfaces of the spine and reconstructed their growth pattern. We show that this spine likely grew posteriorly and proximally from a narrow portion of bone located along the leading edge of the spine. The spine is similarly constructed to the scales with a few exceptions, including the absence of polarized fibers distributed throughout the bone and the presence of a thin layer of perichondral bone. The composition of the spine (semidentine odontodes, dermal bone, perichondral bone) is identical to that of the Romundina dermal plates. These results illustrate the similarities and differences between the dermal tissues in Romundina and indicate that the spine grew differently from the dentinous fin spines from extant and fossil chondrichthyans. The morphology and histology of Romundina is most similar to the fin spine of the probable stem osteichthyan Lophosteus, with a well-developed inner cellular bony base and star-shaped odontodes on the surface. Results from these studies will undoubtedly have impact on our understanding of fossil fin spine histology and evolution, contributing to the on-going revision of early gnathostome phylogeny.
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Affiliation(s)
- Anna Jerve
- Biology Department, Imperial College London, Silwood Park Campus, Ascot, United Kingdom
| | - Qingming Qu
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden
- Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, Ontario, Canada
| | - Sophie Sanchez
- Science for Life Laboratory and Uppsala University, Department of Organismal Biology, Uppsala, Sweden
- European Synchrotron Radiation Facility, Grenoble, France
| | - Per Erik Ahlberg
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden
| | - Tatjana Haitina
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden
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27
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Chevrinais M, Sire JY, Cloutier R. Unravelling the ontogeny of a Devonian early gnathostome, the "acanthodian" Triazeugacanthus affinis (eastern Canada). PeerJ 2017; 5:e3969. [PMID: 29094000 PMCID: PMC5661438 DOI: 10.7717/peerj.3969] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 10/08/2017] [Indexed: 12/01/2022] Open
Abstract
The study of vertebrate ontogenies has the potential to inform us of shared developmental patterns and processes among organisms. However, fossilised ontogenies of early vertebrates are extremely rare during the Palaeozoic Era. A growth series of the Late Devonian “acanthodian” Triazeugacanthus affinis, from the Miguasha Fossil-Fish Lagerstätte, is identified as one of the best known early vertebrate fossilised ontogenies given the exceptional preservation, the large size range, and the abundance of specimens. Morphological, morphometric, histological and chemical data are gathered on a growth series of Triazeugacanthus ranging from 4 to 52 mm in total length. The developmental trajectory of this Devonian “acanthodian” is characteristic of fishes showing a direct development with alternating steps and thresholds. Larvae show no squamation but a progressive appearance of cartilaginous neurocranial and vertebral elements, and appendicular elements, whereas juveniles progress in terms of ossification and squamation. The presence of cartilaginous and bony tissues, discriminated on histological and chemical signatures, shows a progressive mineralisation of neurocranial and vertebral elements. Comparison among different body proportions for larvae, juveniles and adults suggest allometric growth in juveniles. Because of the phylogenetic position of “acanthodians”, Triazeugacanthus ontogeny informs us about deep time developmental conditions in gnathostomes.
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Affiliation(s)
- Marion Chevrinais
- Laboratoire de Paléontologie et Biologie évolutive, Université du Québec à Rimouski, Rimouski, Canada
| | - Jean-Yves Sire
- CNRS-UMR 7138-Evolution Paris-Seine IBPS, Université Pierre et Marie Curie, Paris, France
| | - Richard Cloutier
- Laboratoire de Paléontologie et Biologie évolutive, Université du Québec à Rimouski, Rimouski, Canada
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28
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Johanson Z, Smith M, Sanchez S, Senden T, Trinajstic K, Pfaff C. Questioning hagfish affinities of the enigmatic Devonian vertebrate Palaeospondylus. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170214. [PMID: 28791148 PMCID: PMC5541543 DOI: 10.1098/rsos.170214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 06/20/2017] [Indexed: 06/07/2023]
Abstract
Palaeospondylus gunni Traquair, 1890 is an enigmatic Devonian vertebrate whose taxonomic affinities have been debated since it was first described. Most recently, Palaeospondylus has been identified as a stem-group hagfish (Myxinoidea). However, one character questioning this assignment is the presence of three semicircular canals in the otic region of the cartilaginous skull, a feature of jawed vertebrates. Additionally, new tomographic data reveal that the following characters of crown-group gnathostomes (chondrichthyans + osteichthyans) are present in Palaeospondylus: a longer telencephalic region of the braincase, separation of otic and occipital regions by the otico-occipital fissure, and vertebral centra. As well, a precerebral fontanelle and postorbital articulation of the palatoquadrate are characteristic of certain chondrichthyans. Similarities in the structure of the postorbital process to taxa such as Pucapampella, and possible presence of the ventral cranial fissure, both support a resolution of Pa. gunni as a stem chondrichthyan. The internally mineralized cartilaginous skeleton in Palaeospondylus may represent a stage in the loss of bone characteristic of the Chondrichthyes.
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Affiliation(s)
- Zerina Johanson
- Department of Earth Sciences, Natural History Museum, London, UK
| | - Moya Smith
- Department of Earth Sciences, Natural History Museum, London, UK
- Tissue Engineering and Biophotonics, Dental Institute, King's College London, London, UK
| | - Sophie Sanchez
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden
- European Synchrotron Radiation Facility, Grenoble, France
| | - Tim Senden
- Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Kate Trinajstic
- Environment and Agriculture, Curtin University, Kent Street, Bentley, Perth, Australia
| | - Cathrin Pfaff
- Department of Palaeontology, University of Vienna, Vienna, Austria
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29
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Brazeau MD, Friedman M, Jerve A, Atwood RC. A three-dimensional placoderm (stem-group gnathostome) pharyngeal skeleton and its implications for primitive gnathostome pharyngeal architecture. J Morphol 2017; 278:1220-1228. [PMID: 28543631 PMCID: PMC5575467 DOI: 10.1002/jmor.20706] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 04/22/2017] [Accepted: 04/26/2017] [Indexed: 11/30/2022]
Abstract
The pharyngeal skeleton is a key vertebrate anatomical system in debates on the origin of jaws and gnathostome (jawed vertebrate) feeding. Furthermore, it offers considerable potential as a source of phylogenetic data. Well‐preserved examples of pharyngeal skeletons from stem‐group gnathostomes remain poorly known. Here, we describe an articulated, nearly complete pharyngeal skeleton in an Early Devonian placoderm fish, Paraplesiobatis heinrichsi Broili, from Hunsrück Slate of Germany. Using synchrotron light tomography, we resolve and reconstruct the three‐dimensional gill arch architecture of Paraplesiobatis and compare it with other gnathostomes. The preserved pharyngeal skeleton comprises elements of the hyoid arch (probable ceratohyal) and a series of branchial arches. Limited resolution in the tomography scan causes some uncertainty in interpreting the exact number of arches preserved. However, at least four branchial arches are present. The final and penultimate arches are connected as in osteichthyans. A single median basihyal is present as in chondrichthyans. No dorsal (epibranchial or pharyngobranchial) elements are observed. The structure of the pharyngeal skeleton of Paraplesiobatis agrees well with Pseudopetalichthys from the same deposit, allowing an alternative interpretation of the latter taxon. The phylogenetic significance of Paraplesiobatis is considered. A median basihyal is likely an ancestral gnathostome character, probably with some connection to both the hyoid and the first branchial arch pair. Unpaired basibranchial bones may be independently derived in chondrichthyans and osteichthyans.
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Affiliation(s)
- Martin D Brazeau
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, SL5 7PY, United Kingdom.,Department of Earth Sciences, Natural History Museum, London, SW7 5BD, United Kingdom
| | - Matt Friedman
- Museum of Paleontology and Department of Earth and Environmental Sciences, University of Michigan, 1109 Geddes Ave, Ann Arbor, Michigan, 48109-1079
| | - Anna Jerve
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, SL5 7PY, United Kingdom
| | - Robert C Atwood
- Beamline I12-JEEP, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, UK, OX11 0DE
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30
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Chevrinais M, Sire JY, Cloutier R. From body scale ontogeny to species ontogeny: Histological and morphological assessment of the Late Devonian acanthodian Triazeugacanthus affinis from Miguasha, Canada. PLoS One 2017; 12:e0174655. [PMID: 28403168 PMCID: PMC5389634 DOI: 10.1371/journal.pone.0174655] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 03/13/2017] [Indexed: 11/19/2022] Open
Abstract
Growth series of Palaeozoic fishes are rare because of the fragility of larval and juvenile specimens owing to their weak mineralisation and the scarcity of articulated specimens. This rarity makes it difficult to describe early vertebrate growth patterns and processes in extinct taxa. Indeed, only a few growth series of complete Palaeozoic fishes are available; however, they allow the growth of isolated elements to be described and individual growth from these isolated elements to be inferred. In addition, isolated and in situ scales are generally abundant and well-preserved, and bring information on (1) their morphology and structure relevant to phylogenetic relationships and (2) individual growth patterns and processes relative to species ontogeny. The Late Devonian acanthodian Triazeugacanthusaffinis from the Miguasha Fossil-Lagerstätte preserves one of the best known fossilised ontogenies of early vertebrates because of the exceptional preservation, the large size range, and the abundance of complete specimens. Here, we present morphological, histological, and chemical data on scales from juvenile and adult specimens (scales not being formed in larvae). Histologically, Triazeugacanthus scales are composed of a basal layer of acellular bone housing Sharpey’s fibers, a mid-layer of mesodentine, and a superficial layer of ganoine. Developmentally, scales grow first through concentric addition of mesodentine and bone around a central primordium and then through superposition of ganoine layers. Ontogenetically, scales form first in the region below the dorsal fin spine, then squamation spreads anteriorly and posteriorly, and on fin webs. Phylogenetically, Triazeugacanthus scales show similarities with acanthodians (e.g. “box-in-box” growth), chondrichthyans (e.g. squamation pattern), and actinopterygians (e.g. ganoine). Scale histology and growth are interpreted in the light of a new phylogenetic analysis of gnathostomes supporting acanthodians as stem chondrichthyans.
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Affiliation(s)
| | - Jean-Yves Sire
- UMR 7138-Evolution Paris-Seine, IBPS, Université Pierre et Marie Curie, Paris, France
| | - Richard Cloutier
- Université du Québec à Rimouski, Rimouski, Québec G5L 3A1, Canada
- * E-mail:
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31
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Jerve A, Qu Q, Sanchez S, Blom H, Ahlberg PE. Three-dimensional paleohistology of the scale and median fin spine of Lophosteus superbus (Pander 1856). PeerJ 2016; 4:e2521. [PMID: 27833794 PMCID: PMC5101592 DOI: 10.7717/peerj.2521] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 09/02/2016] [Indexed: 02/04/2023] Open
Abstract
Lophosteus superbus is one of only a handful of probable stem-group osteichthyans known from the fossil record. First collected and described in the late 19th century from the upper Silurian Saaremaa Cliff locality in Estonia, it is known from a wealth of disarticulated scales, fin spines, and bone fragments. In this study we provide the first description of the morphology and paleohistology of a fin spine and scale from Lophosteus using virtual thin sections and 3D reconstructions that were segmented using phase-contrast synchrotron X-ray microtomography. These data reveal that both structures have fully or partially buried odontodes, which retain fine morphological details in older generations, including sharp nodes and serrated ridgelets. The vascular architecture of the fin spine tip, which is composed of several layers of longitudinally directed bone vascular canals, is much more complex compared to the bulbous horizontal canals within the scale, but they both have distinctive networks of ascending canals within each individual odontode. Other histological characteristics that can be observed from the data are cell spaces and Sharpey’s fibers that, when combined with the vascularization, could help to provide insights into the growth of the structure. The 3D data of the scales from Lophosteus superbus is similar to comparable data from other fossil osteichthyans, and the morphology of the reconstructed buried odontodes from this species is identical to scale material of Lophosteus ohesaarensis, casting doubt on the validity of that species. The 3D data presented in this paper is the first for fossil fin spines and so comparable data is not yet available. However, the overall morphology and histology seems to be similar to the structure of placoderm dermal plates. The 3D datasets presented here provide show that microtomography is a powerful tool for investigating the three-dimensional microstructure of fossils, which is difficult to study using traditional histological methods. These results also increase the utility of fin spines and scales suggest that these data are a potentially rich source of morphological data that could be used for studying questions relating to early vertebrate growth and evolution.
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Affiliation(s)
- Anna Jerve
- Department of Organismal Biology, Uppsala Universitet, Uppsala, Sweden.,Department of Life Sciences, Imperial College London, Ascot, United Kingdom
| | - Qingming Qu
- Department of Organismal Biology, Uppsala Universitet, Uppsala, Sweden.,Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, Canada
| | - Sophie Sanchez
- Science of Life Laboratory, Uppsala Universitet, Uppsala, Sweden.,European Synchrotron Radiation Facility, Grenoble, France
| | - Henning Blom
- Department of Organismal Biology, Uppsala Universitet, Uppsala, Sweden
| | - Per Erik Ahlberg
- Department of Organismal Biology, Uppsala Universitet, Uppsala, Sweden
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32
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Ellis NA, Donde NN, Miller CT. Early development and replacement of the stickleback dentition. J Morphol 2016; 277:1072-83. [PMID: 27145214 PMCID: PMC5298556 DOI: 10.1002/jmor.20557] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 04/12/2016] [Accepted: 04/17/2016] [Indexed: 11/09/2022]
Abstract
Teeth have long served as a model system to study basic questions about vertebrate organogenesis, morphogenesis, and evolution. In nonmammalian vertebrates, teeth typically regenerate throughout adult life. Fish have evolved a tremendous diversity in dental patterning in both their oral and pharyngeal dentitions, offering numerous opportunities to study how morphology develops, regenerates, and evolves in different lineages. Threespine stickleback fish (Gasterosteus aculeatus) have emerged as a new system to study how morphology evolves, and provide a particularly powerful system to study the development and evolution of dental morphology. Here, we describe the oral and pharyngeal dentitions of stickleback fish, providing additional morphological, histological, and molecular evidence for homology of oral and pharyngeal teeth. Focusing on the ventral pharyngeal dentition in a dense developmental time course of lab-reared fish, we describe the temporal and spatial consensus sequence of early tooth formation. Early in development, this sequence is highly stereotypical and consists of seventeen primary teeth forming the early tooth field, followed by the first tooth replacement event. Comparing this detailed morphological and ontogenetic sequence to that described in other fish reveals that major changes to how dental morphology arises and regenerates have evolved across different fish lineages. J. Morphol. 277:1072-1083, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Nicholas A. Ellis
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley CA, 94720, USA
| | - Nikunj N. Donde
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley CA, 94720, USA
| | - Craig T. Miller
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley CA, 94720, USA
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33
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Miyashita T, Diogo R. Evolution of Serial Patterns in the Vertebrate Pharyngeal Apparatus and Paired Appendages via Assimilation of Dissimilar Units. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00071] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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34
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Brazeau MD, de Winter V. The hyoid arch and braincase anatomy of Acanthodes support chondrichthyan affinity of 'acanthodians'. Proc Biol Sci 2015; 282:20152210. [PMID: 26674952 PMCID: PMC4707761 DOI: 10.1098/rspb.2015.2210] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/13/2015] [Indexed: 11/24/2022] Open
Abstract
Solving the evolutionary relationships of the acanthodians is one of the key problems in reconstructing ancestral anatomical conditions for the jawed vertebrates (gnathostomes). Current debate concerns whether acanthodians are an assemblage of stem chondrichthyans, or a more generalized grade encompassing some early stem osteichthyans. The skull anatomy of Acanthodes bronni has been pivotal in these debates, owing to tension between chondrichthyan- and osteichthyan-like models of reconstruction. We use computed tomography scanning and traditional palaeontological techniques to resolve the long-standing debate about the anatomy of the jaw suspension. We establish the correct length of the hyomandibula and show that it attaches to a process on the ventrolateral angle of the braincase below the jugular vein groove. This condition corresponds precisely to that in chondrichthyans. This character represents an unambiguously optimized synapomorphy with chondrichthyans given current gnathostome phylogenies, corroborating the growing consensus of the chondrichthyan affinity of acanthodians.
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Affiliation(s)
- Martin D Brazeau
- Naturalis Biodiversity Centre, 9517, 2300 RA, Leiden, The Netherlands
| | - Valerie de Winter
- Institute of Biology, Leiden University, PO Box 9505, 2300 RA, Leiden, The Netherlands
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35
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Giles S, Coates MI, Garwood RJ, Brazeau MD, Atwood R, Johanson Z, Friedman M. Endoskeletal structure in Cheirolepis (Osteichthyes, Actinopterygii), An early ray-finned fish. PALAEONTOLOGY 2015; 58:849-870. [PMID: 27478252 PMCID: PMC4950109 DOI: 10.1111/pala.12182] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/30/2015] [Indexed: 06/06/2023]
Abstract
As the sister lineage of all other actinopterygians, the Middle to Late Devonian (Eifelian-Frasnian) Cheirolepis occupies a pivotal position in vertebrate phylogeny. Although the dermal skeleton of this taxon has been exhaustively described, very little of its endoskeleton is known, leaving questions of neurocranial and fin evolution in early ray-finned fishes unresolved. The model for early actinopterygian anatomy has instead been based largely on the Late Devonian (Frasnian) Mimipiscis, preserved in stunning detail from the Gogo Formation of Australia. Here, we present re-examinations of existing museum specimens through the use of high-resolution laboratory- and synchrotron-based computed tomography scanning, revealing new details of the neuro-cranium, hyomandibula and pectoral fin endoskeleton for the Eifelian Cheirolepis trailli. These new data highlight traits considered uncharacteristic of early actinopterygians, including an uninvested dorsal aorta and imperforate propterygium, and corroborate the early divergence of Cheirolepis within actinopterygian phylogeny. These traits represent conspicuous differences between the endoskeletal structure of Cheirolepis and Mimipiscis. Additionally, we describe new aspects of the parasphenoid, vomer and scales, most notably that the scales display peg-and-socket articulation and a distinct neck. Collectively, these new data help clarify primitive conditions within ray-finned fishes, which in turn have important implications for understanding features likely present in the last common ancestor of living osteichthyans.
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Affiliation(s)
- Sam Giles
- Department of Earth SciencesUniversity of OxfordSouth Parks RoadOxfordOX1 3ANUK
| | - Michael I. Coates
- Department of Organismal Biology and AnatomyUniversity of Chicago1027 E. 57th StreetChicagoIL60637USA
- Committee on Evolutionary BiologyUniversity of Chicago1025 E. 57th StreetChicagoIL60637USA
| | - Russell J. Garwood
- School of Earth, Atmospheric and Environmental SciencesThe University of ManchesterManchesterM13 9PLUK
- The Manchester X‐Ray Imaging FacilitySchool of MaterialsThe University of ManchesterManchesterM13 9PLUK
| | - Martin D. Brazeau
- Department of Life SciencesImperial College LondonSilwood Park CampusBuckhurst RoadAscotSL5 7PYUK
| | - Robert Atwood
- The Joint Engineering and Environmental Processing BeamlineDiamond Light SourceThe Harwell Science and Innovation CampusDidcotOX11 0DEUK
| | - Zerina Johanson
- Department of Earth SciencesNatural History MuseumCromwell RoadLondonSW7 5BDUK
| | - Matt Friedman
- Department of Earth SciencesUniversity of OxfordSouth Parks RoadOxfordOX1 3ANUK
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36
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Brazeau MD, Friedman M. The origin and early phylogenetic history of jawed vertebrates. Nature 2015; 520:490-7. [PMID: 25903631 DOI: 10.1038/nature14438] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 02/09/2015] [Indexed: 11/09/2022]
Abstract
Fossils of early gnathostomes (or jawed vertebrates) have been the focus of study for nearly two centuries. They yield key clues about the evolutionary assembly of the group's common body plan, as well the divergence of the two living gnathostome lineages: the cartilaginous and bony vertebrates. A series of remarkable new palaeontological discoveries, analytical advances and innovative reinterpretations of existing fossil archives have fundamentally altered a decades-old consensus on the relationships of extinct gnathostomes, delivering a new evolutionary framework for exploring major questions that remain unanswered, including the origin of jaws.
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Affiliation(s)
- Martin D Brazeau
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot SL5 7PY, UK
| | - Matt Friedman
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
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37
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Miyashita T. Fishing for jaws in early vertebrate evolution: a new hypothesis of mandibular confinement. Biol Rev Camb Philos Soc 2015; 91:611-57. [DOI: 10.1111/brv.12187] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 03/18/2015] [Accepted: 03/19/2015] [Indexed: 12/21/2022]
Affiliation(s)
- Tetsuto Miyashita
- Department of Biological Sciences; University of Alberta; Edmonton Alberta T6G 2E9 Canada
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38
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Giles S, Friedman M, Brazeau MD. Osteichthyan-like cranial conditions in an Early Devonian stem gnathostome. Nature 2015; 520:82-5. [PMID: 25581798 PMCID: PMC5536226 DOI: 10.1038/nature14065] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 11/11/2014] [Indexed: 11/09/2022]
Abstract
The phylogeny of Silurian and Devonian (443-358 million years (Myr) ago) fishes remains the foremost problem in the study of the origin of modern gnathostomes (jawed vertebrates). A central question concerns the morphology of the last common ancestor of living jawed vertebrates, with competing hypotheses advancing either a chondrichthyan- or osteichthyan-like model. Here we present Janusiscus schultzei gen. et sp. nov., an Early Devonian (approximately 415 Myr ago) gnathostome from Siberia previously interpreted as a ray-finned fish, which provides important new information about cranial anatomy near the last common ancestor of chondrichthyans and osteichthyans. The skull roof of Janusiscus resembles that of early osteichthyans, with large plates bearing vermiform ridges and partially enclosed sensory canals. High-resolution computed tomography (CT) reveals a braincase bearing characters typically associated with either chondrichthyans (large hypophyseal opening accommodating the internal carotid arteries) or osteichthyans (facial nerve exiting through jugular canal, endolymphatic ducts exiting posterior to the skull roof) but lacking a ventral cranial fissure, the presence of which is considered a derived feature of crown gnathostomes. A conjunction of well-developed cranial processes in Janusiscus helps unify the comparative anatomy of early jawed vertebrate neurocrania, clarifying primary homologies in 'placoderms', osteichthyans and chondrichthyans. Phylogenetic analysis further supports the chondrichthyan affinities of 'acanthodians', and places Janusiscus and the enigmatic Ramirosuarezia in a polytomy with crown gnathostomes. The close correspondence between the skull roof of Janusiscus and that of osteichthyans suggests that an extensive dermal skeleton was present in the last common ancestor of jawed vertebrates, but ambiguities arise from uncertainties in the anatomy of Ramirosuarezia. The unexpected contrast between endoskeletal structure in Janusiscus and its superficially osteichthyan-like dermal skeleton highlights the potential importance of other incompletely known Siluro-Devonian 'bony fishes' for reconstructing patterns of trait evolution near the origin of modern gnathostomes.
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Affiliation(s)
- Sam Giles
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, UK
| | - Matt Friedman
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, UK
| | - Martin D Brazeau
- 1] Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, the Netherlands [2] Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot SL5 7PY, UK
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Copulation in antiarch placoderms and the origin of gnathostome internal fertilization. Nature 2014; 517:196-9. [DOI: 10.1038/nature13825] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 08/29/2014] [Indexed: 11/08/2022]
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