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Williams C, Kirby A, Marghoub A, Kéver L, Ostashevskaya-Gohstand S, Bertazzo S, Moazen M, Abzhanov A, Herrel A, Evans SE, Vickaryous M. A review of the osteoderms of lizards (Reptilia: Squamata). Biol Rev Camb Philos Soc 2021; 97:1-19. [PMID: 34397141 PMCID: PMC9292694 DOI: 10.1111/brv.12788] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 07/30/2021] [Accepted: 08/03/2021] [Indexed: 12/24/2022]
Abstract
Osteoderms are mineralised structures consisting mainly of calcium phosphate and collagen. They form directly within the skin, with or without physical contact with the skeleton. Osteoderms, in some form, may be primitive for tetrapods as a whole, and are found in representatives of most major living lineages including turtles, crocodilians, lizards, armadillos, and some frogs, as well as extinct taxa ranging from early tetrapods to dinosaurs. However, their distribution in time and space raises questions about their evolution and homology in individual groups. Among lizards and their relatives, osteoderms may be completely absent; present only on the head or dorsum; or present all over the body in one of several arrangements, including non-overlapping mineralised clusters, a continuous covering of overlapping plates, or as spicular mineralisations that thicken with age. This diversity makes lizards an excellent focal group in which to study osteoderm structure, function, development and evolution. In the past, the focus of researchers was primarily on the histological structure and/or the gross anatomy of individual osteoderms in a limited sample of taxa. Those studies demonstrated that lizard osteoderms are sometimes two-layered structures, with a vitreous, avascular layer just below the epidermis and a deeper internal layer with abundant collagen within the deep dermis. However, there is considerable variation on this model, in terms of the arrangement of collagen fibres, presence of extra tissues, and/or a cancellous bone core bordered by cortices. Moreover, there is a lack of consensus on the contribution, if any, of osteoblasts in osteoderm development, despite research describing patterns of resorption and replacement that would suggest both osteoclast and osteoblast involvement. Key to this is information on development, but our understanding of the genetic and skeletogenic processes involved in osteoderm development and patterning remains minimal. The most common proposition for the presence of osteoderms is that they provide a protective armour. However, the large morphological and distributional diversity in lizard osteoderms raises the possibility that they may have other roles such as biomechanical reinforcement in response to ecological or functional constraints. If lizard osteoderms are primarily for defence, whether against predators or conspecifics, then this 'bony armour' might be predicted to have different structural and/or mechanical properties compared to other hard tissues (generally intended for support and locomotion). The cellular and biomineralisation mechanisms by which osteoderms are formed could also be different from those of other hard tissues, as reflected in their material composition and nanostructure. Material properties, especially the combination of malleability and resistance to impact, are of interest to the biomimetics and bioinspired material communities in the development of protective clothing and body armour. Currently, the literature on osteoderms is patchy and is distributed across a wide range of journals. Herein we present a synthesis of current knowledge on lizard osteoderm evolution and distribution, micro- and macrostructure, development, and function, with a view to stimulating further work.
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Affiliation(s)
- Catherine Williams
- Department of Biomedical Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.,Department of Biology, Aarhus University, Ny Munkegade 114-116, Aarhus C, DK-8000, Denmark
| | - Alexander Kirby
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, U.K.,Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, U.K
| | - Arsalan Marghoub
- Department of Mechanical Engineering, University College London, London, WC1E 7JE, U.K
| | - Loïc Kéver
- Département Adaptations du Vivant, UMR 7179 MECADEV C.N.R.S/M.N.H.N., Bâtiment d'Anatomie Comparée, 55 rue Buffon, Paris, 75005, France
| | - Sonya Ostashevskaya-Gohstand
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, Silwood Park Campus, Berkshire, SL5 7PY, U.K
| | - Sergio Bertazzo
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, U.K
| | - Mehran Moazen
- Department of Mechanical Engineering, University College London, London, WC1E 7JE, U.K
| | - Arkhat Abzhanov
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, Silwood Park Campus, Berkshire, SL5 7PY, U.K
| | - Anthony Herrel
- Département Adaptations du Vivant, UMR 7179 MECADEV C.N.R.S/M.N.H.N., Bâtiment d'Anatomie Comparée, 55 rue Buffon, Paris, 75005, France
| | - Susan E Evans
- Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, U.K
| | - Matt Vickaryous
- Department of Biomedical Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
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Mann A, Calthorpe AS, Maddin HC. Joermungandr bolti, an exceptionally preserved 'microsaur' from the Mazon Creek Lagerstätte reveals patterns of integumentary evolution in Recumbirostra. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210319. [PMID: 34295525 PMCID: PMC8292758 DOI: 10.1098/rsos.210319] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 06/24/2021] [Indexed: 05/14/2023]
Abstract
The Carboniferous Pennsylvanian-aged (309-307 Ma) Mazon Creek Lagerstätte produces some of the earliest fossils of major Palaeozoic tetrapod lineages. Recently, several new tetrapod specimens collected from Mazon Creek have come to light, including the earliest fossorially adapted recumbirostrans. Here, we describe a new long-bodied recumbirostran, Joermungandr bolti gen. et sp. nov., known from a single part and counterpart concretion bearing a virtually complete skeleton. Uniquely, Joermungandr preserves a full suite of dorsal, flank and ventral dermal scales, together with a series of thinned and reduced gastralia. Investigation of these scales using scanning electron microscopy reveals ultrastructural ridge and pit morphologies, revealing complexities comparable to the scale ultrastructure of extant snakes and fossorial reptiles, which have scales modified for body-based propulsion and shedding substrate. Our new taxon also represents an important early record of an elongate recumbirostran bauplan, wherein several features linked to fossoriality, including a characteristic recumbent snout, are present. We used parsimony phylogenetic methods to conduct phylogenetic analysis using the most recent recumbirostran-focused matrix. The analysis recovers Joermungandr within Recumbirostra with likely affinities to the sister clades Molgophidae and Brachystelechidae. Finally, we review integumentary patterns in Recumbirostra, noting reductions and losses of gastralia and osteoderms associated with body elongation and, thus, probably also associated with increased fossoriality.
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Affiliation(s)
- Arjan Mann
- Department of Earth Sciences, Carleton University, 2115 Herzberg Laboratories,1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
| | - Ami S. Calthorpe
- Department of Earth Sciences, Carleton University, 2115 Herzberg Laboratories,1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
| | - Hillary C. Maddin
- Department of Earth Sciences, Carleton University, 2115 Herzberg Laboratories,1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
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Laver RJ, Morales CH, Heinicke MP, Gamble T, Longoria K, Bauer AM, Daza JD. The development of cephalic armor in the tokay gecko (Squamata: Gekkonidae:
Gekko gecko
). J Morphol 2019; 281:213-228. [DOI: 10.1002/jmor.21092] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 11/26/2019] [Accepted: 12/11/2019] [Indexed: 01/07/2023]
Affiliation(s)
- Rebecca J. Laver
- Research School of Biology Australian National University Canberra Australia
| | - Cristian H. Morales
- Department of Biological Sciences Sam Houston State University Huntsville Texas
- Department of Biology University of Texas at Arlington Arlington Texas
| | - Matthew P. Heinicke
- Department of Natural Sciences University of Michigan‐Dearborn Dearborn Michigan
| | - Tony Gamble
- Department of Biological Sciences Marquette University Milwaukee Wisconsin
- Milwaukee Public Museum Milwaukee Wisconsin
- Bell Museum of Natural History University of Minnesota Saint Paul Minnesota
| | - Kristin Longoria
- Department of Biological Sciences Sam Houston State University Huntsville Texas
| | - Aaron M. Bauer
- Department of Biology Villanova University Villanova Pennsylvania
| | - Juan D. Daza
- Department of Biological Sciences Sam Houston State University Huntsville Texas
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Cerda IA, Desojo JB, Trotteyn MJ, Scheyer TM. Osteoderm histology of Proterochampsia and Doswelliidae (Reptilia: Archosauriformes) and their evolutionary and paleobiological implications. J Morphol 2015; 276:385-402. [DOI: 10.1002/jmor.20348] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 10/05/2014] [Accepted: 11/18/2014] [Indexed: 11/06/2022]
Affiliation(s)
- Ignacio A. Cerda
- Conicet: Rivadavia 1917; Buenos Aires 1000-1499 Argentina
- Instituto de Investigación en Paleobiología y Geología; Universidad Nacional de Río Negro, Museo Carlos Ameghino, Belgrano 1700, Paraje Pichi Ruca (predio Marabunta); 8300 Cipolletti Río Negro Argentina
| | - Julia B. Desojo
- Conicet: Rivadavia 1917; Buenos Aires 1000-1499 Argentina
- Sección Paleontología Vertebrados; Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Ángel Gallardo 470 C1405DJR; Buenos Aires Argentina
| | - María J. Trotteyn
- Conicet: Rivadavia 1917; Buenos Aires 1000-1499 Argentina
- INGEO. Instituto de Geología, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan. Ignacio de la Rosa 590 (oeste), Complejo Universitario Islas Malvinas; San Juan Argentina CP 5400
| | - Torsten M. Scheyer
- Paläontologisches Institut und Museum der Universität Zürich; Karl Schmid-Strasse 4, CH-8006 Zürich Switzerland
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de Buffrénil V, Clarac F, Fau M, Martin S, Martin B, Pellé E, Laurin M. Differentiation and growth of bone ornamentation in vertebrates: a comparative histological study among the Crocodylomorpha. J Morphol 2014; 276:425-45. [PMID: 25488816 DOI: 10.1002/jmor.20351] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 10/27/2014] [Accepted: 11/08/2014] [Indexed: 11/06/2022]
Abstract
Bone ornamentation, that is, hollow (pits and grooves) or protruding (ridges) repetitive reliefs on the surface of dermal bones, is a frequent, though poorly studied and understood, feature in vertebrates. One of the most typical examples of this characteristic is given by the Crurotarsi, a taxon formed by the crocodilians and their closest allies, which generally display deep ornamentation on skull roof and osteoderms. However, the ontogenetic process responsible for the differentiation and development of this character remains controversial. This study was conducted to settle the question on histological and microanatomical evidence in several crurotarsan taxa. Observational and experimental data in extant and extinct crocodyliforms show that bone ornamentation is initially created, and later maintained during somatic growth (that is indefinite in crocodilians), by a complex process of bone remodeling comprising local resorption of superficial bone cortices, followed by partial reconstruction. The superficial reliefs of crocodilian dermal bones are thus permanently modified through pit enlargement, drift, stretching, shrinking, or complete filling. Ridges are also remodeled in corresponding ways. These processes allow accommodation of unitary ornamental motifs to the overall dimensions of the bones during growth. A parsimony optimization based on the results of this study, but integrating also published data on bone histology in non-crocodyliform crurotarsans and some non-crurotarsan taxa, suggests that the peculiar mechanism described above for creating and maintaining bone ornamentation is a general feature of the Crurotarsi and is quite distinct from that attributed by previous authors to other vertebrates.
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Affiliation(s)
- V de Buffrénil
- Département Histoire de la Terre, Muséum National d'Histoire Naturelle, UMR 7207 (CR2P), Sorbonne Universités, MNHN/CNRS/UPMC, Bâtiment de Géologie Paris Cedex 05, F-75231, France
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Scheyer TM, Desojo JB, Cerda IA. Bone Histology of Phytosaur, Aetosaur, and Other Archosauriform Osteoderms (Eureptilia, Archosauromorpha). Anat Rec (Hoboken) 2013; 297:240-60. [DOI: 10.1002/ar.22849] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 10/22/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Torsten M. Scheyer
- Paläontologisches Institut und Museum der Universität Zürich; Karl Schmid-Strasse 4, CH-8006 Zürich Switzerland
| | - Julia B. Desojo
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
- Sección Paleontología Vertebrados; Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Ángel Gallardo 470 C1405DJR Buenos Aires Argentina
| | - Ignacio A. Cerda
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
- Instituto de Investigación en Paleobiología y Geología; Universidad Nacional de Río Negro; Museo Carlos Ameghino, Belgrano 1700, Paraje Pichi Ruca (predio Marabunta), 8300 Cipolletti Río Negro Argentina
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