The origin of snakes (Serpentes) as seen through eye anatomy |
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| Authors: | CHRISTOPHER L CAPRETTE MICHAEL S Y LEE RICHARD SHINE ALLIE MOKANY JERRY F DOWNHOWER |
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| Institution: | Department of Evolution, Ecology, and Organismal Biology, 300 Aronoff Laboratory, 318 W 12th Ave., The Ohio State University, Columbus, OH, 43210, USA; Department of Palaeontology, The South Australian Museum &Department of Environmental Biology, University of Adelaide, North Terrace, Adelaide 5000, Australia; School of Biological Sciences, The University of Sydney, Sydney, NSW, 2006, Australia; 26/22 Archibald St., Lyneham ACT 2602, Australia |
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| Abstract: | Snakes evolved from lizards but have dramatically different eyes. These differences are cited widely as compelling evidence that snakes had fossorial and nocturnal ancestors. Their eyes, however, also exhibit similarities to those of aquatic vertebrates. We used a comparative analysis of ophthalmic data among vertebrate taxa to evaluate alternative hypotheses concerning the ecological origin of the distinctive features of the eyes of snakes. In parsimony and phenetic analyses, eye and orbital characters retrieved groupings more consistent with ecological adaptation rather than accepted phylogenetic relationships. Fossorial lizards and mammals cluster together, whereas snakes are widely separated from these taxa and instead cluster with primitively aquatic vertebrates. This indicates that the eyes of snakes most closely resemble those of aquatic vertebrates, and suggests that the early evolution of snakes occurred in aquatic environments. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 81 , 469–482. |
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| Keywords: | adaptation Alethinophidia ophthalmic morphology parsimony analysis Scolecophidia vertebrate evolution |
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