1
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Scheyer TM. The pseudosuchian record in paleohistology: A small review. Anat Rec (Hoboken) 2024. [PMID: 38655735 DOI: 10.1002/ar.25455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 03/25/2024] [Accepted: 03/30/2024] [Indexed: 04/26/2024]
Abstract
Archosauria originated around the Earth's largest biotic crisis that severely affected all ecosystems globally, the Permotriassic Mass extinction event, and comprises two crown-group lineages: the bird-lineage and the crocodylian lineage. The bird lineage includes the iconic pterosaurs, as well as dinosaurs and birds, whereas the crocodylian lineage includes clades such as aetosaurs, poposaurs, "rauisuchians," as well as Crocodylomorpha; the latter being represented today only by less than 30 extant species of Crocodylia. Despite playing important roles during Mesozoic and Cenozoic ecosystems, both on land and in water, Pseudosuchia received far less attention compared to the bird-lineage, which is also reflected in number and scope of histological studies so far. Lately, the field has seen a shift of focus toward pseudosuchians, however, and the symposium on "Paleohistological Inferences of Paleobiological Traits in Pseudosuchia" held during the International Congress of Vertebrate Morphology 2023 in Cairns, Queensland, Australia, is the latest proof of that. To put these novel aspects of paleohistological and paleobiological research into context, an overview of the non-extant pseudosuchian taxa whose postcranial bones were studied so far is provided here (c. 80 species out of a total of more than 700 extinct species described) and recent trends in pseudosuchian osteohistology are highlighted. In addition, histological studies on cranial and dental material and other potential hard tissues, such as eggshells and otoliths, are briefly reviewed as well.
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Affiliation(s)
- Torsten M Scheyer
- Department of Paleontology, University of Zurich, Zurich, Switzerland
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2
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Chinsamy A. Palaeoecological deductions from osteohistology. Biol Lett 2023; 19:20230245. [PMID: 37607578 PMCID: PMC10444344 DOI: 10.1098/rsbl.2023.0245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 07/31/2023] [Indexed: 08/24/2023] Open
Abstract
Palaeoecological deductions are vital for understanding the evolution and diversification of species within prehistoric environments. This review highlights the multitude of ways in which the microanatomy and microscopic structure of bones enables palaeoecological deductions. The occurrence of growth marks in bones is discussed, and their usefulness in deducing the ontogenetic status and age of individuals is considered, as well as how such marks in bones permit the assessment of the growth dynamics of individuals and species. Here osteohistology is shown to provide insight into the structure of past populations, as well as ecological relationships between individuals. In addition, the response of bones to trauma, disease and moulting is considered. Finally, I explore how osteohistology can give insight into ecomorphological adaptations, such as filter feeding, probe feeding and saltatorial locomotion. Methodological advances in three-dimensional microtomography and synchrotron scanning bodes well for future studies in osteohistology and despite some compromises in terms of tissue identity, circumvents the crucial issue of destructive analyses.
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Affiliation(s)
- Anusuya Chinsamy
- Department of Biological Sciences, University of Cape Town, John Day Building, University Avenue, Rondebosch 7700, South Africa
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3
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Frýdlová P, Janovská V, Mrzílková J, Halašková M, Riegerová M, Dudák J, Tymlová V, Žemlička J, Zach P, Frynta D. The first description of dermal armour in snakes. Sci Rep 2023; 13:6405. [PMID: 37076516 PMCID: PMC10115820 DOI: 10.1038/s41598-023-33244-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 04/10/2023] [Indexed: 04/21/2023] Open
Abstract
Osteoderms, also called dermal armour, often play a role in predator defence. The presence of osteoderms is highly irregularly distributed across the squamate phylogeny and they have not been found in snakes. In this study, we searched for candidate snake species that would benefit from such armour to protect their body, focusing primarily on fossorial species with defensive tail displays. We examined the tail morphology of 27 snake species from different families using micro-computed tomography (µCT) and micro- radiography. We discovered dermal armour in four species of sand boas (Erycidae) that also feature enlarged and highly modified caudal vertebrae. This is the first description of dermal armour in snakes. Ancestral state reconstructions revealed that osteoderms likely evolved once or multiple times in Erycidae. We have not found osteoderms in any other examined snake species. Nevertheless, similar structures are known from unrelated squamate clades, such as gerrhosaurids and geckos. This supports the idea of underlying deep developmental homology. We propose the hypothesis that osteoderms protect sand boas like the "brigandine armour" of medieval warriors. We interpret it as another component of the sand boas' rich defence strategy.
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Affiliation(s)
- Petra Frýdlová
- Department of Zoology, Faculty of Science, Charles University, 128 43, Prague, Czech Republic
- Department of Anatomy, Third Faculty of Medicine, Charles University, 100 00, Prague, Czech Republic
| | - Veronika Janovská
- Department of Zoology, Faculty of Science, Charles University, 128 43, Prague, Czech Republic
| | - Jana Mrzílková
- Department of Anatomy, Third Faculty of Medicine, Charles University, 100 00, Prague, Czech Republic
| | - Milada Halašková
- Department of Histology and Embryology, Third Faculty of Medicine, Charles University, 100 00, Prague, Czech Republic
| | - Markéta Riegerová
- Department of Histology and Embryology, Third Faculty of Medicine, Charles University, 100 00, Prague, Czech Republic
| | - Jan Dudák
- Institute of Experimental and Applied Physics, Czech Technical University in Prague, 110 00, Prague, Czech Republic
| | - Veronika Tymlová
- Institute of Experimental and Applied Physics, Czech Technical University in Prague, 110 00, Prague, Czech Republic
| | - Jan Žemlička
- Institute of Experimental and Applied Physics, Czech Technical University in Prague, 110 00, Prague, Czech Republic
| | - Petr Zach
- Department of Anatomy, Third Faculty of Medicine, Charles University, 100 00, Prague, Czech Republic
| | - Daniel Frynta
- Department of Zoology, Faculty of Science, Charles University, 128 43, Prague, Czech Republic.
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4
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Tagliavento M, Davies AJ, Bernecker M, Staudigel PT, Dawson RR, Dietzel M, Götschl K, Guo W, Schulp AS, Therrien F, Zelenitsky DK, Gerdes A, Müller W, Fiebig J. Evidence for heterothermic endothermy and reptile-like eggshell mineralization in Troodon, a non-avian maniraptoran theropod. Proc Natl Acad Sci U S A 2023; 120:e2213987120. [PMID: 37011196 PMCID: PMC10104568 DOI: 10.1073/pnas.2213987120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 02/15/2023] [Indexed: 04/05/2023] Open
Abstract
The dinosaur-bird transition involved several anatomical, biomechanical, and physiological modifications of the theropod bauplan. Non-avian maniraptoran theropods, such as Troodon, are key to better understand changes in thermophysiology and reproduction occurring during this transition. Here, we applied dual clumped isotope (Δ47 and Δ48) thermometry, a technique that resolves mineralization temperature and other nonthermal information recorded in carbonates, to eggshells from Troodon, modern reptiles, and modern birds. Troodon eggshells show variable temperatures, namely 42 and 29 ± 2 °C, supporting the hypothesis of an endothermic thermophysiology with a heterothermic strategy for this extinct taxon. Dual clumped isotope data also reveal physiological differences in the reproductive systems between Troodon, reptiles, and birds. Troodon and modern reptiles mineralize their eggshells indistinguishable from dual clumped isotope equilibrium, while birds precipitate eggshells characterized by a positive disequilibrium offset in Δ48. Analyses of inorganic calcites suggest that the observed disequilibrium pattern in birds is linked to an amorphous calcium carbonate (ACC) precursor, a carbonate phase known to accelerate eggshell formation in birds. Lack of disequilibrium patterns in reptile and Troodon eggshells implies these vertebrates had not acquired the fast, ACC-based eggshell calcification process characteristic of birds. Observation that Troodon retained a slow reptile-like calcification suggests that it possessed two functional ovaries and was limited in the number of eggs it could produce; thus its large clutches would have been laid by several females. Dual clumped isotope analysis of eggshells of extinct vertebrates sheds light on physiological information otherwise inaccessible in the fossil record.
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Affiliation(s)
- Mattia Tagliavento
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
| | - Amelia J. Davies
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
| | - Miguel Bernecker
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
| | - Philip T. Staudigel
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
| | - Robin R. Dawson
- Department of Earth, Geographic and Climate Sciences, University of Massachusetts, Amherst, MA01003
| | - Martin Dietzel
- Institute of Applied Geosciences, Graz University of Technology,8010Graz, Austria
| | - Katja Götschl
- Institute of Applied Geosciences, Graz University of Technology,8010Graz, Austria
| | - Weifu Guo
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA02543
| | - Anne S. Schulp
- Vertebrate Evolution and Development, Naturalis Biodiversity Center,2333CRLeiden, the Netherlands
- Department of Earth Sciences, Faculty of Geosciences, Universiteit Utrecht,3584 CBUtrecht, the Netherlands
| | | | | | - Axel Gerdes
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
- Frankfurt Isotope and Element Research Center, Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
| | - Wolfgang Müller
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
- Frankfurt Isotope and Element Research Center, Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
| | - Jens Fiebig
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
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5
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Sena MVDA, Marinho TDS, Montefeltro FC, Langer MC, Fachini TS, Nava WR, Pinheiro AEP, de Araújo EV, Aubier P, de Andrade RCLP, Sayão JM, de Oliveira GR, Cubo J. Osteohistological characterization of notosuchian osteoderms: Evidence for an overlying thick leathery layer of skin. J Morphol 2023; 284:e21536. [PMID: 36394285 PMCID: PMC10107732 DOI: 10.1002/jmor.21536] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 10/12/2022] [Accepted: 11/16/2022] [Indexed: 11/18/2022]
Abstract
Osteoderms are mineralized structures embedded in the dermis, known for nonavian archosaurs, squamates, xenarthrans, and amphibians. Herein, we compared the osteoderm histology of Brazilian Notosuchia of Cretaceous age using three neosuchians for comparative purposes. Microanatomical analyses showed that most of them present a diploe structure similar to those of other pseudosuchians, lizards, and turtles. This structure contains two cortices (the external cortex composed of an outer and an inner layers, and the basal cortex) and a core in-between them. Notosuchian osteoderms show high bone compactness (>0.85) with varying degrees of cancellous bone in the core. The neosuchian Guarinisuchus shows the lowest bone compactness with a well-developed cancellous layer. From an ontogenetic perspective, most tissues are formed through periosteal ossification, although the mineralized tissues observed in baurusuchid LPRP/USP 0634 suggest a late metaplastic development. Histology suggests that the ossification center of notosuchian osteoderm is located at the keel. Interestingly, we identified Sharpey's fibers running perpendicularly to the outer layer of the external cortex in Armadillosuchus arrudai, Itasuchus jesuinoi, and Baurusuchidae (LPRP/USP 0642). This feature indicates a tight attachment within the dermis, and it is evidence for the presence of an overlying thick leathery layer of skin over these osteoderms. These data allow a better understanding of the osteohistological structure of crocodylomorph dermal bones, and highlight their structural diversity. We suggest that the vascular canals present in some sampled osteoderms connecting the inner layer of the external cortex and the core with the external surface may increase osteoderm surface and the capacity of heat transfer in terrestrial notosuchians.
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Affiliation(s)
- Mariana Valéria de Araújo Sena
- Centre de Recherche en Paléontologie Paris (CR2P, UMR 7207), Muséum national d'Histoire naturelle, CNRS, Sorbonne Université, Paris, France.,Centro de Ciências Biológicas e da Saúde, Laboratório de Paleontologia da URCA, Universidade Regional do Cariri, Rua Carolino Sucupira-Pimenta, Crato, Ceará, Brazil
| | - Thiago da Silva Marinho
- Centro de Pesquisas Paleontológicas "Llewellyn Ivor Price", Complexo Cultural e Científico Peirópolis, Pró-Reitoria de Extensão Universitária, Universidade Federal do Triângulo Mineiro, Uberaba, Minas Gerais, Brazil.,Instituto de Ciências Exatas, Naturais e Educação, Universidade Federal do Triângulo Mineiro, Uberaba, Minas Gerais, Brazil
| | - Felipe Chinaglia Montefeltro
- Departamento de Biologia e Zootecnia, Faculdade de Engenharia de Ilha Solteira, Universidade Estadual Paulista, Ilha Solteira, São Paulo, Brazil
| | - Max Cardoso Langer
- Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Laboratório de Paleontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Thiago Schineider Fachini
- Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Laboratório de Paleontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - William Roberto Nava
- Museu de Paleontologia de Marília, Prefeitura Municipal de Marília, Marília, São Paulo, Brazil
| | | | - Esaú Victor de Araújo
- Museu Nacional do Rio de Janeiro, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Paul Aubier
- Centre de Recherche en Paléontologie Paris (CR2P, UMR 7207), Muséum national d'Histoire naturelle, CNRS, Sorbonne Université, Paris, France
| | - Rafael César Lima Pedroso de Andrade
- Centro de Ciências Biológicas e da Saúde, Laboratório de Paleontologia da URCA, Universidade Regional do Cariri, Rua Carolino Sucupira-Pimenta, Crato, Ceará, Brazil
| | - Juliana Manso Sayão
- Museu Nacional do Rio de Janeiro, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gustavo Ribeiro de Oliveira
- Laboratório de Paleontologia e Sistemática (LAPASI), Departamento de Biologia, Universidade Federal Rural de Pernambuco, Recife, Pernambuco, Brazil
| | - Jorge Cubo
- Centre de Recherche en Paléontologie Paris (CR2P, UMR 7207), Muséum national d'Histoire naturelle, CNRS, Sorbonne Université, Paris, France
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6
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Broeckhoven C. Intraspecific competition: A missing link in dermal armour evolution? J Anim Ecol 2022; 91:1562-1566. [PMID: 35633188 DOI: 10.1111/1365-2656.13749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 05/23/2022] [Indexed: 11/29/2022]
Abstract
Predation is widely regarded as an important selective force in the evolution and maintenance of dermal armour; yet, the basic premise that predation and armour are strongly linked to each other has proven to be difficult to assess. In this concept, I put forward the fighting-advantage hypothesis, the view that aggressive interactions with conspecifics, not predation, might have been a key selective pressure in the evolution of dermal armour. Considering intraspecific competition as a potential explanation could not only reveal previously overlooked aspects of the functional and evolutionary significance of dermal armour, but also advance the emerging field of biomimetics in which such knowledge forms the starting point of technological innovation.
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Affiliation(s)
- Chris Broeckhoven
- Laboratory of Functional Morphology, Department of Biology, University of Antwerp, Wilrijk, Belgium
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7
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Broeckhoven C, du Plessis A. Osteoderms as calcium reservoirs: Insights from the lizard Ouroborus cataphractus. J Anat 2022; 241:635-640. [PMID: 35502528 DOI: 10.1111/joa.13683] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 04/13/2022] [Accepted: 04/13/2022] [Indexed: 11/27/2022] Open
Abstract
The functional significance of osteoderms-bony elements embedded in the dermis-remains a topic of much debate. Although many hypotheses have been put forward in the past, the idea that osteoderms can serve as calcium reservoirs has received little experimental attention thus far. In this study, we use micro-computed tomography to investigate inter- and intrasexual variation in osteoderm density in the viviparous lizard Ouroborus cataphractus and conduct histochemical analyses to unravel the potential mechanism involved in mineral resorption from the osteoderms. Our results show that females have denser, more compact osteoderms than males of similar body sizes, regardless of the season during which they were collected and their reproductive state. Furthermore, a histochemical study demonstrates the presence of mononucleated TRAP-positive cells in the vascular canals of the osteoderms. Based on the findings of this study, we suggest that the mineral storage hypothesis merits further attention as a candidate explanation for osteoderm evolution.
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Affiliation(s)
- Chris Broeckhoven
- Laboratory of Functional Morphology, University of Antwerp, Wilrijk, Belgium
| | - Anton du Plessis
- Object Research Systems, Montreal, Canada.,Research group 3D Innovation, Stellenbosch University, Stellenbosch, South Africa
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8
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9
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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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10
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Schucht PJ, Rühr PT, Geier B, Glaw F, Lambertz M. Armored with skin and bone: A combined histological and
μCT
‐study of the exceptional integument of the
Antsingy
leaf chameleon
Brookesia perarmata
(Angel, 1933). J Morphol 2020; 281:754-764. [DOI: 10.1002/jmor.21135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 04/12/2020] [Accepted: 04/17/2020] [Indexed: 12/20/2022]
Affiliation(s)
- Pia J. Schucht
- Institut für ZoologieRheinische Friedrich‐Wilhelms‐Universität Bonn, Poppelsdorfer Schloss Bonn Germany
| | - Peter T. Rühr
- AG Morphologische DynamikenInstitut für Zoologie, Biozentrum, Universität zu Köln Köln Germany
- Zentrum für Molekulare BiodiversitätsforschungZoologisches Forschungsmuseum Alexander Koenig Bonn Germany
| | - Benedikt Geier
- Max Planck Institute for Marine Microbiology Bremen Germany
| | - Frank Glaw
- Sektion HerpetologieZoologische Staatssammlung München (ZSM‐SNSB) Munich Germany
| | - Markus Lambertz
- Institut für ZoologieRheinische Friedrich‐Wilhelms‐Universität Bonn, Poppelsdorfer Schloss Bonn Germany
- Sektion HerpetologieZoologisches Forschungsmuseum Alexander Koenig Bonn Germany
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11
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Iacoviello F, Kirby AC, Javanmardi Y, Moeendarbary E, Shabanli M, Tsolaki E, Sharp AC, Hayes MJ, Keevend K, Li JH, Brett DJL, Shearing PR, Olivo A, Herrmann IK, Evans SE, Moazen M, Bertazzo S. The multiscale hierarchical structure of Heloderma suspectum osteoderms and their mechanical properties. Acta Biomater 2020; 107:194-203. [PMID: 32109598 DOI: 10.1016/j.actbio.2020.02.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 02/13/2020] [Accepted: 02/18/2020] [Indexed: 12/27/2022]
Abstract
Osteoderms are hard tissues embedded in the dermis of vertebrates and have been suggested to be formed from several different mineralized regions. However, their nano architecture and micro mechanical properties had not been fully characterized. Here, using electron microscopy, µ-CT, atomic force microscopy and finite element simulation, an in-depth characterization of osteoderms from the lizard Heloderma suspectum, is presented. Results show that osteoderms are made of three different mineralized regions: a dense apex, a fibre-enforced region comprising the majority of the osteoderm, and a bone-like region surrounding the vasculature. The dense apex is stiff, the fibre-enforced region is flexible and the mechanical properties of the bone-like region fall somewhere between the other two regions. Our finite element analyses suggest that when combined into the osteoderm structure, the distinct tissue regions are able to shield the body of the animal by bearing the external forces. These findings reveal the structure-function relationship of the Heloderma suspectum osteoderm in unprecedented detail. STATEMENT OF SIGNIFICANCE: The structures of bone and teeth have been thoroughly investigated. They provide a basis not only for understanding the mechanical properties and functions of these hard tissues, but also for the de novo design of composite materials. Osteoderms, however, are hard tissues that must possess mechanical properties distinct from teeth and bone to function as a protective armour. Here we provide a detailed analysis of the nanostructure of vertebrate osteoderms from Heloderma suspectum, and show that their mechanical properties are determined by their multiscale hierarchical tissue. We believe this study contributes to advance the current knowledge of the structure-function relationship of the hierarchical structures in the Heloderma suspectum osteoderm. This knowledge might in turn provide a source of inspiration for the design of bioinspired and biomimetic materials.
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Affiliation(s)
- Francesco Iacoviello
- Electrochemical Innovation Lab, Department of Chemical Engineering, University College London, London WC1E 7JE, UK
| | - Alexander C Kirby
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
| | - Yousef Javanmardi
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK
| | - Emad Moeendarbary
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Murad Shabanli
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK
| | - Elena Tsolaki
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
| | - Alana C Sharp
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Matthew J Hayes
- Department of Ophthalmology, University College London, London WC1E 6BT, UK
| | - Kerda Keevend
- Department of Materials, Meet Life, Swiss Federal Laboratories for Materials Science and Technology, (Empa), Lerchenfeldstrasse 5, CH-9014 St. Gallen, Switzerland
| | - Jian-Hao Li
- Department of Materials, Meet Life, Swiss Federal Laboratories for Materials Science and Technology, (Empa), Lerchenfeldstrasse 5, CH-9014 St. Gallen, Switzerland
| | - Daniel J L Brett
- Electrochemical Innovation Lab, Department of Chemical Engineering, University College London, London WC1E 7JE, UK
| | - Paul R Shearing
- Electrochemical Innovation Lab, Department of Chemical Engineering, University College London, London WC1E 7JE, UK
| | - Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
| | - Inge K Herrmann
- Department of Materials, Meet Life, Swiss Federal Laboratories for Materials Science and Technology, (Empa), Lerchenfeldstrasse 5, CH-9014 St. Gallen, Switzerland
| | - Susan E Evans
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Mehran Moazen
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK
| | - Sergio Bertazzo
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK.
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12
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Canoville A, Schweitzer MH, Zanno L. Identifying medullary bone in extinct avemetatarsalians: challenges, implications and perspectives. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190133. [PMID: 31928189 DOI: 10.1098/rstb.2019.0133] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Medullary bone (MB) is a sex-specific tissue produced by female birds during the laying cycle, and it is hypothesized to have arisen within Avemetatarsalia, possibly outside Avialae. Over the years, researchers have attempted to define a set of criteria from which to evaluate the nature of purported MB-like tissues recovered from fossil specimens. However, we argue that the prevalence, microstructural and chemical variability of MB in Neornithes is, as of yet, incompletely known and thus current diagnoses of MB do not capture the extent of variability that exists in modern birds. Based on recently published data and our own observations of MB distribution and structure using computed tomography and histochemistry, we attempt to advance the discourse on identifying MB in fossil specimens. We propose: (i) new insights into the phylogenetic breadth and structural diversity of MB within extant birds; (ii) a reevaluation and refinement of the most recently published list of criteria suggested for confidently identifying MB in the fossil record; (iii) reconsideration of some prior identifications of MB-like tissues in fossil specimens by taking into account the newly acquired data; and (iv) discussions on the challenges of characterizing MB in Neornithes with the goal of improving its diagnosis in extinct avemetatarsalians. This article is part of the theme issue 'Vertebrate palaeophysiology'.
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Affiliation(s)
- Aurore Canoville
- Paleontology, North Carolina Museum of Natural Sciences, Raleigh, NC 27601, USA.,Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Mary H Schweitzer
- Paleontology, North Carolina Museum of Natural Sciences, Raleigh, NC 27601, USA.,Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA.,Museum of the Rockies, Montana State University, Bozeman, MT 59717, USA.,Department of Geology, Lund University, 223 62 Lund, Sweden
| | - Lindsay Zanno
- Paleontology, North Carolina Museum of Natural Sciences, Raleigh, NC 27601, USA.,Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA
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13
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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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14
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Bailleul AM, O’Connor J, Schweitzer MH. Dinosaur paleohistology: review, trends and new avenues of investigation. PeerJ 2019; 7:e7764. [PMID: 31579624 PMCID: PMC6768056 DOI: 10.7717/peerj.7764] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 08/26/2019] [Indexed: 12/12/2022] Open
Abstract
In the mid-19th century, the discovery that bone microstructure in fossils could be preserved with fidelity provided a new avenue for understanding the evolution, function, and physiology of long extinct organisms. This resulted in the establishment of paleohistology as a subdiscipline of vertebrate paleontology, which has contributed greatly to our current understanding of dinosaurs as living organisms. Dinosaurs are part of a larger group of reptiles, the Archosauria, of which there are only two surviving lineages, crocodilians and birds. The goal of this review is to document progress in the field of archosaur paleohistology, focusing in particular on the Dinosauria. We briefly review the "growth age" of dinosaur histology, which has encompassed new and varied directions since its emergence in the 1950s, resulting in a shift in the scientific perception of non-avian dinosaurs from "sluggish" reptiles to fast-growing animals with relatively high metabolic rates. However, fundamental changes in growth occurred within the sister clade Aves, and we discuss this major evolutionary transition as elucidated by histology. We then review recent innovations in the field, demonstrating how paleohistology has changed and expanded to address a diversity of non-growth related questions. For example, dinosaur skull histology has elucidated the formation of curious cranial tissues (e.g., "metaplastic" tissues), and helped to clarify the evolution and function of oral adaptations, such as the dental batteries of duck-billed dinosaurs. Lastly, we discuss the development of novel techniques with which to investigate not only the skeletal tissues of dinosaurs, but also less-studied soft-tissues, through molecular paleontology and paleohistochemistry-recently developed branches of paleohistology-and the future potential of these methods to further explore fossilized tissues. We suggest that the combination of histological and molecular methods holds great potential for examining the preserved tissues of dinosaurs, basal birds, and their extant relatives. This review demonstrates the importance of traditional bone paleohistology, but also highlights the need for innovation and new analytical directions to improve and broaden the utility of paleohistology, in the pursuit of more diverse, highly specific, and sensitive methods with which to further investigate important paleontological questions.
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Affiliation(s)
- Alida M. Bailleul
- Key Laboratory of Vertebrate Evolution and Human Origins of the Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing, China
| | - Jingmai O’Connor
- Key Laboratory of Vertebrate Evolution and Human Origins of the Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing, China
| | - Mary H. Schweitzer
- Department of Biology, North Carolina State University, Raleigh, NC, USA
- North Carolina Museum of Natural Science, Raleigh, NC, USA
- Department of Geology, Lund University, Lund, Sweden
- Museum of the Rockies, Montana State University, Bozeman, MT, USA
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15
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Heterogeneous bioapatite carbonation in western painted turtles is unchanged after anoxia. Comp Biochem Physiol A Mol Integr Physiol 2019; 233:74-83. [PMID: 30930203 DOI: 10.1016/j.cbpa.2019.03.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 02/09/2019] [Accepted: 03/25/2019] [Indexed: 11/23/2022]
Abstract
Adsorbed and structurally incorporated carbonate in bioapatite, the primary mineral phase of bone, is observed across vertebrates, typically at 2-8 wt%, and supports critical physiological and biochemical functions. Several turtle species contain elevated bone-associated carbonate, a property linked to pH buffering and overwintering survival. Prior studies of turtle bone utilized bulk analyses, which do not provide spatial resolution of carbonate. Using Raman spectroscopy, the goals of this study were to: (1) quantify and spatially resolve carbonate heterogeneity within the turtle shell; (2) determine if cortical and trabecular bone contain distinct carbonate concentrations; and (3) assess if simulated overwintering conditions result in decreased bioapatite carbonation. Here, we demonstrate the potential for Raman spectroscopic analysis to spatially resolve bioapatite carbonation, using the western painted turtle as a model species. Carbonate concentration was highly variable within cortical and trabecular bone, based on calibrated Raman spot analyses and mapping, suggesting heterogeneous carbonate distribution among crystallites. Mean carbonate concentration did not significantly differ between cortical and trabecular bone, which indicates random distribution of crystallites with elevated and depleted carbonate. Carbonate concentrations (range: 5-22 wt%) were not significantly different in overwintering and control animals, deviating from previous bulk analyses. In reconciling bulk and Raman analyses, two hypotheses explain how overwintering turtles potentially access carbonate: (1) mobilization of mineral-associated, surface components of bone crystallites; and (2) selective, dispersed crystallite dissolution. Elevated bioapatite carbonate in the western painted turtle, averaging 11.8 wt%, represents the highest carbonation observed in vertebrates, and is one physiological trait that facilitates overwintering survival.
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16
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The crocodylian skull and osteoderms: A functional exaptation to ectothermy? ZOOLOGY 2018; 132:31-40. [PMID: 30736927 DOI: 10.1016/j.zool.2018.12.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 12/08/2018] [Accepted: 12/11/2018] [Indexed: 10/27/2022]
Abstract
The crocodylians are ectothermic semi-aquatic vertebrates which are assessed to have evolved from endothermic terrestrial forms during the Mesozoic. Such a physiological transition should have involved modifications in their cardio-vascular system allowing to increase the heat transfers with the surrounding environment by growing a peripheral vascularization which would be mainly located in the dermal skeleton: the dermatocranium and the osteoderms. In order to assess the implication of these anatomical regions in thermal exchanges, we have recorded the temperature above a set of representative skin areas in order to draw comparisons between the skull, the osteoderms, and the rest of the body parts which present either none or residual dermal ossification. We computed the data after the specimens were successively laid in different stereotyped environmental conditions which involved significant variations in the environmental temperature. Our results show that the osteoderms collect the external heat during the basking periods as they become significantly warmer than the surrounding skin; they further release the heat into the core of the organism as they turn out to be colder than the surrounding skin after a significant cooling period. In disregard of the environmental temperature variations, the skull table (which encloses the braincase) remains warmer than the rest of the cranial regions and shows less temperature variations than the osteoderms; a result which has lead us to think that the braincase temperature is monitored and controlled by a thermoregulatory system. Therefore, as hypothesized by previous authors regarding the ectothermic diapsids, we assume that the crocodylian skull possesses shunting blood pathways which tend to maintain both the braincase and the main sensory organs at the nearest to the optimal physiological temperature depending on the external temperature variations. Concerning the skin vascularization, the study of an albino Alligator mississippiensis specimen permitted to observe the repartition of the superficial blood vessels by transparency through the skin. We thus testify that the skin which covers either the skull or the osteoderms is more vascularized than the skin which does not present any subjacent dermal ossification. We consequently deduce that the significant contrast in the thermal behavior between the dermal skeleton and the rest of the body is indeed correlated with a difference in the relative degree of skin vascularization. This last assessment confirms that the development of the dermal skeleton should have played a functional role in the crocodylian transition from endothermy to ectothermy through the set-up of a peripheral vessel network.
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17
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Li Q, Zhao X, Wang S, Zhou Z. Letrozole induced low estrogen levels affected the expressions of duodenal and renal calcium-processing gene in laying hens. Gen Comp Endocrinol 2018; 255:49-55. [PMID: 29037849 DOI: 10.1016/j.ygcen.2017.10.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 10/06/2017] [Accepted: 10/10/2017] [Indexed: 11/29/2022]
Abstract
Estrogen regulates the calcium homeostasis in hens, but the mechanisms involved are still unclear fully. In this study, we investigated whether letrozole (LZ) induced low estrogen levels affected the calcium absorption and transport in layers. In the duodenum, we observed a significant decrease of mRNA expressions of Calbindin-28k (CaBP-28k) and plasma membrane Ca2+-ATPase (PMCA 1b) while CaBP-28k protein expression was declined in birds with LZ treatment, and the mRNA levels of duodenal transient receptor potential vanilloid 6 (TRPV6) and Na+/Ca2+ exchanger 1 (NCX1) were not affected. Interestingly, we observed the different changes in the kidney. The renal mRNA expressions of TRPV6 and NCX1 were unregulated while the PMCA1b was down-regulated in low estrogen layers, however, the CaBP-28k gene and protein expressions were no changed in the kidney. Furthermore, it showed that the duodenal estradiol receptor 2 (ESR2) transcripts rather than parathyroid hormone 1 receptor (PTH1R) and calcitonin receptor (CALCR) played key roles to down-regulate calcium transport in LZ-treated birds. In conclusion, CaBP-28k, PMCA 1b and ESR2 genes in the duodenum may be primary targets for estrogen regulation in order to control calcium homeostasis in hens.
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Affiliation(s)
- Qiao Li
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Xingkai Zhao
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Shujie Wang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Zhenlei Zhou
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
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18
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English LT. Variation in crocodilian dorsal scute organization and geometry with a discussion of possible functional implications. J Morphol 2017; 279:154-162. [DOI: 10.1002/jmor.20760] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 09/22/2017] [Accepted: 09/26/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Lauren T. English
- Department of Geology, Jackson School of Geosciences; The University of Texas at Austin; Austin Texas U.S.A
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19
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Dubansky BH, Dubansky BD. Natural development of dermal ectopic bone in the american alligator (Alligator mississippiensis
) resembles heterotopic ossification disorders in humans. Anat Rec (Hoboken) 2017; 301:56-76. [DOI: 10.1002/ar.23682] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 07/25/2017] [Accepted: 08/17/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Brooke H. Dubansky
- Department of Medical Laboratory Sciences and Public Health; Tarleton State University; 1501 Enderly Place, Fort Worth Texas
| | - Benjamin D. Dubansky
- Department of Biological Sciences; University of North Texas, 1511 W. Sycamore St; Denton Texas
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20
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Broeckhoven C, de Kock C, Mouton PLFN. Sexual dimorphism in osteoderm expression and the role of male intrasexual aggression. Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blx066] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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21
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Paluh DJ, Griffing AH, Bauer AM. Sheddable armour: identification of osteoderms in the integument of Geckolepis maculata (Gekkota). AFR J HERPETOL 2017. [DOI: 10.1080/21564574.2017.1281172] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Daniel J. Paluh
- Villanova University, Department of Biology, Villanova, PA 19085, USA
- Department of Biology and Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, USA
| | - Aaron H. Griffing
- Villanova University, Department of Biology, Villanova, PA 19085, USA
- Marquette University, Department of Biological Sciences, Milwaukee, WI 53233, USA
| | - Aaron M. Bauer
- Villanova University, Department of Biology, Villanova, PA 19085, USA
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22
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Functional trade-off between strength and thermal capacity of dermal armor: Insights from girdled lizards. J Mech Behav Biomed Mater 2017; 74:189-194. [PMID: 28605722 DOI: 10.1016/j.jmbbm.2017.06.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 06/04/2017] [Accepted: 06/06/2017] [Indexed: 01/02/2023]
Abstract
The presence of dermal armor is often unambiguously considered the result of an evolutionary predator-prey arms-race. Recent studies focusing predominantly on osteoderms - mineralized elements embedded in the dermis layer of various extant and extinct vertebrates - have instead proposed that dermal armor might exhibit additional functionalities besides protection. Multiple divergent functionalities could impose conflicting demands on a phenotype, yet, functional trade-offs in dermal armor have rarely been investigated. Here, we use high-resolution micro-computed tomography and voxel-based simulations to test for a trade-off between the strength and thermal capacity of osteoderms using two armored cordylid lizards as model organisms. We demonstrate that high vascularization, associated with improved thermal capacity might limit the strength of osteoderms. These results call for a holistic, cautionary future approach to studies investigating dermal armor, especially those aiming to inspire artificial protective materials.
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23
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Vidal D, Ortega F, Gascó F, Serrano-Martínez A, Sanz JL. The internal anatomy of titanosaur osteoderms from the Upper Cretaceous of Spain is compatible with a role in oogenesis. Sci Rep 2017; 7:42035. [PMID: 28169348 DOI: 10.1038/srep42035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 12/30/2016] [Indexed: 11/09/2022] Open
Abstract
Dermal armor is one of the most intriguing features of some titanosaurs, the only sauropod dinosaurs that bore osteoderms. Some studies have revealed cavities of varying sizes inside some titanosaur osteoderms, interpreted as the result of bone remodeling for mineral mobilization. Several hypotheses have been proposed to explain the need for mineral mobilization in titanosaurs. However, rejecting those hypotheses was difficult with hitherto available evidence. The Upper Cretaceous site of Lo Hueco (Cuenca; Spain) has yielded one of the largest titanosaur osteoderm sets available. Observation of pre-existing breakages in the fossils and CT-scanning have revealed a predominant internal channel network for bulb and root osteoderms: most had a very compact spongy bone core, perfused by large longitudinal branching neurovascular canals. Only few osteoderms from the same bed, which was deposited in a single and short event, had areas with low-density spongy bone. This void-like low-density bone is always associated with internal channels. It is also present in osteoderms of different sizes. This scenario is best explained when considering that Lo Hueco titanosaurs might have used their osteoderms as a source of calcium that was mobilized during oogenesis, although other hypotheses cannot be completely ruled out.
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Affiliation(s)
- Daniel Vidal
- Grupo de Biología Evolutiva, UNED, Paseo Senda del Rey 9, 28040, Madrid, Spain.,Unidad de Paleontología, Universidad Autónoma de Madrid, C/Darwin 2 28049, Madrid, Spain
| | - Francisco Ortega
- Grupo de Biología Evolutiva, UNED, Paseo Senda del Rey 9, 28040, Madrid, Spain
| | - Francisco Gascó
- Grupo de Biología Evolutiva, UNED, Paseo Senda del Rey 9, 28040, Madrid, Spain
| | | | - José Luis Sanz
- Unidad de Paleontología, Universidad Autónoma de Madrid, C/Darwin 2 28049, Madrid, Spain
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