image: High-density shape data used to quantify the skull diversity of lizards, snakes, and worm lizards. view more
Credit: Image courtesy of Akinobu Watanabe.
A study finds that the wide range of skull features in snake and lizard species is likely due to evolutionary selection acting on a conserved set of skull shape variations. Squamates are an order of reptiles encompassing snakes and lizards, with a range of body shapes and sizes adapted to various ecological niches and habitats. Such diversity presents challenges in systematically describing the variations seen across the squamates. Akinobu Watanabe, Anjali Goswami, and colleagues used high-density shape analysis to quantify digital models of skulls from 181 living and extinct squamates to compare shapes of cranial partitions in each species and correlate the variation among those shapes with evolutionary, ecological, and developmental factors. The authors found that diet and habitat exerted strong influence on skull shape, with aquatic and burrowing squamates exhibiting rapid evolution. Diet shaped the jaw muscles in lizards and the jaw articulation, important in gape widening, in snakes. Reconstructing the ancestry of squamates based on the skulls suggested that snakes may have arisen from a terrestrial, nonburrowing ancestor. According to the authors, the skull traits displayed conserved correlations with each other, suggesting that the wide range of diversity reflects the action of evolutionary selection on a common pattern of skull variation.
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Article #18-20967: "Ecomorphological diversification in squamates from conserved pattern of cranial integration," by Akinobu Watanabe et al.
MEDIA CONTACT: Akinobu Watanabe, New York Institute of Technology, Old Westbury, NY; tel: 516-686-3978; e-mail: <awatanab@nyit.edu>; Anjali Goswami, Natural History Museum, London, UNITED KINGDOM; tel: +44 (0)20 7942 5063; e-mail: <a.goswami@nhm.ac.uk>
Journal
Proceedings of the National Academy of Sciences