Limb reduction in squamate reptiles correlates with the reduction of the chondrocranium: A case study on serpentiform anguids. Issue 9 (15th February 2021)

• Record Type: Journal Article
• Authors: Yaryhin, Oleksandr; Klembara, Jozef; Pichugin, Yuriy; Kaucka, Marketa; Werneburg, Ingmar
• Other Names: Sears Karen guestEditor.; Gros Jerome guestEditor.; Davey Megan guestEditor.
• Is Part Of: Developmental dynamics. Volume 250:Issue 9(2021)
• Page Start: 1300
• Page End: 1317
• Publication Date: 2021-02-15
• Subjects: body elongation -- chondrocranium -- development -- lepidosaurs -- limb reduction -- limblessness -- pleiotropy -- reptiles -- skull; Morphogenesis -- Periodicals; Anatomy -- Periodicals; Anatomie -- Périodiques; Biologie du développement -- Périodiques; 571.833
• DOI: 10.1002/dvdy.307
• Languages: English
• ISSNs: 1058-8388

Abstract

Abstract: Background: In vertebrates, the skull evolves from a complex network of dermal bones and cartilage—the latter forming the pharyngeal apparatus and the chondrocranium. Squamates are particularly important in this regard as they maintain at least part of the chondrocranium throughout their whole ontogeny until adulthood. Anguid lizards represent a unique group of squamates, which contains limbed and limbless forms and show conspicuous variation of the adult skull. Results: Based on several emboadryonic stages of the limbless lizards Pseudopus apodus and Anguis fragilis, and by comparing with other squamates, we identified and interpreted major differences in chondrocranial anatomy. Among others, the most important differences are in the orbitotemporal region. P. apodus shows a strikingly similar development of this region to other squamates. Unexpectedly, however, A. fragilis differs considerably in the composition of the orbitotemporal region. In addition, A. fragilis retains a paedomorphic state of the nasal region. Conclusions: Taxonomic comparisons indicate that even closely related species with reduced limbs show significant differences in chondrocranial anatomy. The Pearson correlation coefficient suggests strong correlation between chondrocranial reduction and limb reduction. We pose the hypothesis that limb reduction could be associated with the reduction in chondrocrania by means of genetic mechanisms. Key Findings: Taxonomic comparisons indicate that even closely related species with reduced limbs show significant differences in the chondrocranial anatomy. Limb rudimentation lead to the diversification of the orbitotemporal region complexity. The Pearson correlation coefficient suggests strong correlation between chondrocranial reduction and limb reduction. Limb reduction could be associated with the reduction in chondrocrania by means of genetic mechanisms.