The role of cranial osteoderms on the mechanics of the skull in scincid lizards

Marghoub, Arsalan; Kéver, Loïc; Williams, Catherine J.; Abzhanov, Arhat; Vickaryous, Matthew K.; Herrel, Anthony; Evans, SE; Moazen, Mehran

doi:10.1002/ar.25168

Cited by 3 publications

(1 citation statement)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recently, it has been shown that cranial osteoderms of extant lizards take up a large amount of bite‐induced stress in the skull (Marghoub et al, 2023), meaning that the skull shape that we see in modern taxa might just be a fracture of the stresses in early reptilian forms with less dermal armor (Figure 17c) being unaltered because only osteoderms might have allowed the animals to evolve higher bite forces.…”

Section: Diversity and Evolution Among Land Vertebratesmentioning

confidence: 90%

Evolution of the temporal skull openings in land vertebrates: A hypothetical framework on the basis of biomechanics

Werneburg,

Preuschoft

2024

The Anatomical Record

View full text Add to dashboard Cite

The complex constructions of land vertebrate skulls have inspired a number of functional analyses. In the present study, we provide a basic view on skull biomechanics and offer a framework for more general observations using advanced modeling approaches in the future. We concentrate our discussion on the cranial openings in the temporal skull region and work out two major, feeding‐related factors that largely influence the shape of the skull. We argue that (1) the place where the most forceful biting is conducted and (2) the handling of resisting food (sideward movements) constitute the formation and shaping of either one or two temporal arcades surrounding these openings. Diversity in temporal skull anatomy among amniotes can be explained by specific modulations of these factors with different amounts of acting forces which inevitably lead to deposition or reduction of bone material. For example, forceful anterior bite favors an infratemporal bar, whereas forceful posterior bite favors formation of an upper temporal arcade. Transverse forces (inertia and resistance of seized objects) as well as neck posture also influence the shaping of the temporal region. Considering their individual skull morphotypes, we finally provide hypotheses on the feeding adaptation in a variety of major tetrapod groups. We did not consider ligaments, internal bone structure, or cranial kinesis in our considerations. Involving those in quantitative tests of our hypotheses, such as finite element system synthesis, will provide a comprehensive picture on cranial mechanics and evolution in the future.

show abstract

Section: Diversity and Evolution Among Land Vertebratesmentioning

confidence: 90%

Evolution of the temporal skull openings in land vertebrates: A hypothetical framework on the basis of biomechanics

Werneburg,

Preuschoft

2024

The Anatomical Record

View full text Add to dashboard Cite

show abstract

Comparative analysis of osteoderms across the lizard body

Maliuk,

Marghoub,

Williams

et al. 2024

The Anatomical Record

View full text Add to dashboard Cite

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.

show abstract

BounTI (boundary‐preserving threshold iteration): A user‐friendly tool for automatic hard tissue segmentation

Didziokas,

Pauws,

Kölby

et al. 2024

Journal of Anatomy

View full text Add to dashboard Cite

X‐ray Computed Tomography (CT) images are widely used in various fields of natural, physical, and biological sciences. 3D reconstruction of the images involves segmentation of the structures of interest. Manual segmentation has been widely used in the field of biological sciences for complex structures composed of several sub‐parts and can be a time‐consuming process. Many tools have been developed to automate the segmentation process, all with various limitations and advantages, however, multipart segmentation remains a largely manual process. The aim of this study was to develop an open‐access and user‐friendly tool for the automatic segmentation of calcified tissues, specifically focusing on craniofacial bones. Here we describe BounTI, a novel segmentation algorithm which preserves boundaries between separate segments through iterative thresholding. This study outlines the working principles behind this algorithm, investigates the effect of several input parameters on its outcome, and then tests its versatility on CT images of the craniofacial system from different species (e.g. a snake, a lizard, an amphibian, a mouse and a human skull) with various scan qualities. The case studies demonstrate that this algorithm can be effectively used to segment the craniofacial system of a range of species automatically. High‐resolution microCT images resulted in more accurate boundary‐preserved segmentation, nonetheless significantly lower‐quality clinical images could still be segmented using the proposed algorithm. Methods for manual intervention are included in this tool when the scan quality is insufficient to achieve the desired segmentation results. While the focus here was on the craniofacial system, BounTI can be used to automatically segment any hard tissue. The tool presented here is available as an Avizo/Amira add‐on, a stand‐alone Windows executable, and a Python library. We believe this accessible and user‐friendly segmentation tool can benefit the wider anatomical community.

show abstract

The role of cranial osteoderms on the mechanics of the skull in scincid lizards

Cited by 3 publications

References 47 publications

Evolution of the temporal skull openings in land vertebrates: A hypothetical framework on the basis of biomechanics

Evolution of the temporal skull openings in land vertebrates: A hypothetical framework on the basis of biomechanics

Comparative analysis of osteoderms across the lizard body

BounTI (boundary‐preserving threshold iteration): A user‐friendly tool for automatic hard tissue segmentation

Contact Info

Product

Resources

About