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Maliuk A, Marghoub A, Williams CJA, Stanley E, Kéver L, Vickaryous M, Herrel A, Evans SE, Moazen M. Comparative analysis of osteoderms across the lizard body. Anat Rec (Hoboken) 2024. [PMID: 38396371 DOI: 10.1002/ar.25418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 12/12/2023] [Accepted: 02/11/2024] [Indexed: 02/25/2024]
Abstract
Osteoderms (ODs) are mineralized tissue embedded within the skin and are particularly common in reptiles. They are generally thought to form a protective layer between the soft tissues of the animal and potential external threats, although other functions have been proposed. The aim of this study was to characterize OD variation across the lizard body. Adults of three lizard species were chosen for this study. After whole body CT scanning of each lizard, single ODs were extracted from 10 different anatomical regions, CT scanned, and characterized using sectioning and nanoindentation. Morphological analysis and material characterization revealed considerable diversity in OD structure across the species investigated. The scincid Tiliqua gigas was the only studied species in which ODs had a similar external morphology across the head and body. Greater osteoderm diversity was found in the gerrhosaurid Broadleysaurus major and the scincid Tribolonotus novaeguineae. Dense capping tissue, like that reported for Heloderma, was found in only one of the three species examined, B. major. Osteoderm structure can be surprisingly complex and variable, both among related taxa, and across the body of individual animals. This raises many questions about OD function but also about the genetic and developmental factors controlling OD shape.
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Affiliation(s)
- Anastasiia Maliuk
- Department of Mechanical Engineering, University College London, London, UK
- Department of Zoology, National Museum of Natural History, NAS of Ukraine, Kyiv, Ukraine
| | - Arsalan Marghoub
- Department of Mechanical Engineering, University College London, London, UK
| | - Catherine J A Williams
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada
- Department of Biology, Aarhus University, Aarhus, Denmark
- Department of Animal and Veterinary Sciences, Aarhus University, Tjele, Denmark
| | - Edward Stanley
- Department of Natural History, Florida Museum of Natural History, Gainesville, Florida, USA
| | - Loïc Kéver
- Département Adaptations du Vivant, UMR7179 CNRS/MNHN, Paris, France
| | - Matthew Vickaryous
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Anthony Herrel
- Département Adaptations du Vivant, UMR7179 CNRS/MNHN, Paris, France
- Department of Biology, Evolutionary Morphology of Vertebrates, Ghent University, Ghent, Belgium
- Department of Biology, University of Antwerp, Wilrijk, Belgium
- Naturhistorisches Museum Bern, Bern, Switzerland
| | - Susan E Evans
- Department of Cell and Developmental Biology, University College London, London, UK
| | - Mehran Moazen
- Department of Mechanical Engineering, University College London, London, UK
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Marghoub A, Kéver L, Williams CJA, Abzhanov A, Vickaryous M, Herrel A, Evans SE, Moazen M. The role of cranial osteoderms on the mechanics of the skull in scincid lizards. Anat Rec (Hoboken) 2023; 306:2415-2424. [PMID: 36748783 DOI: 10.1002/ar.25168] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 01/04/2023] [Accepted: 01/04/2023] [Indexed: 02/08/2023]
Abstract
Osteoderms (ODs) are calcified organs formed directly within the skin of most major extant tetrapod lineages. Lizards possibly show the greatest diversity in ODs morphology and distribution. ODs are commonly hypothesized to function as a defensive armor. Here we tested the hypothesis that cranial osteoderms also contribute to the mechanics of the skull during biting. A series of in vivo experiments were carried out on three specimens of Tiliqua gigas. Animals were induced to bite a force plate while a single cranial OD was strain gauged. A finite element (FE) model of a related species, Tiliqua scincoides, was developed and used to estimate the level of strain across the same OD as instrumented in the in vivo experiments. FE results were compared to the in vivo data and the FE model was modified to test two hypothetical scenarios in which all ODs were (i) removed from, and (ii) fused to, the skull. In vivo data demonstrated that the ODs were carrying load during biting. The hypothetical FE models showed that when cranial ODs were fused to the skull, the overall strain across the skull arising from biting was reduced. Removing the ODs showed an opposite effect. In summary, our findings suggest that cranial ODs contribute to the mechanics of the skull, even when they are loosely attached.
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Affiliation(s)
- Arsalan Marghoub
- Department of Mechanical Engineering, University College London, London, UK
| | - Loïc Kéver
- Département Adaptations du Vivant, Bâtiment, UMR 7179 MECADEV C.N.R.S/M.N.H.N, d'Anatomie Comparée, Paris, France
| | - Catherine J A Williams
- Department of Biology, Aarhus University, Aarhus C, Denmark
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Arkhat Abzhanov
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, Silkwood Park Campus, Berkshire, UK
| | - Matthew Vickaryous
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Anthony Herrel
- Département Adaptations du Vivant, Bâtiment, UMR 7179 MECADEV C.N.R.S/M.N.H.N, d'Anatomie Comparée, Paris, France
| | - Susan E Evans
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London, UK
| | - Mehran Moazen
- Department of Mechanical Engineering, University College London, London, UK
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Fitzpatrick LLJ, Ligabue-Braun R, Nekaris KAI. Slowly Making Sense: A Review of the Two-Step Venom System within Slow ( Nycticebus spp.) and Pygmy Lorises ( Xanthonycticebus spp.). Toxins (Basel) 2023; 15:514. [PMID: 37755940 PMCID: PMC10536643 DOI: 10.3390/toxins15090514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 08/16/2023] [Accepted: 08/18/2023] [Indexed: 09/28/2023] Open
Abstract
Since the early 2000s, studies of the evolution of venom within animals have rapidly expanded, offering new revelations on the origins and development of venom within various species. The venomous mammals represent excellent opportunities to study venom evolution due to the varying functional usages, the unusual distribution of venom across unrelated mammals and the diverse variety of delivery systems. A group of mammals that excellently represents a combination of these traits are the slow (Nycticebus spp.) and pygmy lorises (Xanthonycticebus spp.) of south-east Asia, which possess the only confirmed two-step venom system. These taxa also present one of the most intriguing mixes of toxic symptoms (cytotoxicity and immunotoxicity) and functional usages (intraspecific competition and ectoparasitic defence) seen in extant animals. We still lack many pieces of the puzzle in understanding how this venom system works, why it evolved what is involved in the venom system and what triggers the toxic components to work. Here, we review available data building upon a decade of research on this topic, focusing especially on why and how this venom system may have evolved. We discuss that research now suggests that venom in slow lorises has a sophisticated set of multiple uses in both intraspecific competition and the potential to disrupt the immune system of targets; we suggest that an exudate diet reveals several toxic plants consumed by slow and pygmy lorises that could be sequestered into their venom and which may help heal venomous bite wounds; we provide the most up-to-date visual model of the brachial gland exudate secretion protein (BGEsp); and we discuss research on a complement component 1r (C1R) protein in saliva that may solve the mystery of what activates the toxicity of slow and pygmy loris venom. We conclude that the slow and pygmy lorises possess amongst the most complex venom system in extant animals, and while we have still a lot more to understand about their venom system, we are close to a breakthrough, particularly with current technological advances.
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Affiliation(s)
- Leah Lucy Joscelyne Fitzpatrick
- Nocturnal Primate Research Group, Department of Social Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
- Centre for Functional Genomics, Department of Health and Life Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Rodrigo Ligabue-Braun
- Department of Pharmacosciences, Federal University of Health Sciences of Porto Alegre (UFCSPA), Avenida Sarmento Leite 245, Porto Alegre 90050-170, Brazil
| | - K Anne-Isola Nekaris
- Nocturnal Primate Research Group, Department of Social Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
- Centre for Functional Genomics, Department of Health and Life Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
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Arbour VM, Zanno LE, Evans DC. Palaeopathological evidence for intraspecific combat in ankylosaurid dinosaurs. Biol Lett 2022; 18:20220404. [PMID: 36475422 PMCID: PMC9727678 DOI: 10.1098/rsbl.2022.0404] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Ankylosaurid dinosaurs were heavily armoured herbivores with tails modified into club-like weapons. These tail clubs have widely been considered defensive adaptations wielded against predatory theropod dinosaurs. Here we argue instead that ankylosaurid tail clubs were sexually selected structures used primarily for intraspecific combat. We found pathological osteoderms (armour plates) in the holotype specimen of Zuul crurivastator, which are localized to the flanks in the hip region rather than distributed randomly across the body, consistent with injuries inflicted by lateral tail-swinging and ritualized combat. We failed to find convincing evidence for predation as a key selective pressure in the evolution of the tail club. High variation in tail club size through time, and delayed ontogenetic growth of the tail club further support the sexual selection hypothesis. There is little doubt that the tail club could have been used in defence when needed, but our results suggest that sexual selection drove the evolution of this impressive weapon. This changes the prevailing view of ankylosaurs, suggesting they were behaviorally complex animals that likely engaged in ritualized combat for social dominance as in other ornithischian dinosaurs and mammals.
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Affiliation(s)
- Victoria M. Arbour
- Department of Knowledge, Royal BC Museum, Victoria, British Columbia, Canada,School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada
| | - Lindsay E. Zanno
- Paleontology, North Carolina Museum of Natural Sciences, Raleigh, NC, USA,Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA
| | - David C. Evans
- Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
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