The oldest known snakes from the Middle Jurassic-Lower Cretaceous provide insights on snake evolution

The previous oldest known fossil snakes date from ~100 million year old sediments (Upper Cretaceous) and are both morphologically and phylogenetically diverse, indicating that snakes underwent a much earlier origin and adaptive radiation. We report here on snake fossils that extend the record backwa...

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Bibliographic Details
Published in:Nature communications 2015-01, Vol.6 (1), p.5996-5996, Article 5996
Main Authors: Caldwell, Michael W., Nydam, Randall L., Palci, Alessandro, Apesteguía, Sebastián
Format: Article
Language:English
Subjects:
631/181/414
631/181/757
Animals
Biological Evolution
Fossils
Geography
Humanities and Social Sciences
Jaw - anatomy & histology
multidisciplinary
Paleontology
Phylogeny
Phylogeography
Science
Science (multidisciplinary)
Skull - anatomy & histology
Snakes - anatomy & histology
Snakes - classification
Species Specificity
Spine - anatomy & histology
Time Factors
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Summary:The previous oldest known fossil snakes date from ~100 million year old sediments (Upper Cretaceous) and are both morphologically and phylogenetically diverse, indicating that snakes underwent a much earlier origin and adaptive radiation. We report here on snake fossils that extend the record backwards in time by an additional ~70 million years (Middle Jurassic-Lower Cretaceous). These ancient snakes share features with fossil and modern snakes (for example, recurved teeth with labial and lingual carinae, long toothed suborbital ramus of maxillae) and with lizards (for example, pronounced subdental shelf/gutter). The paleobiogeography of these early snakes is diverse and complex, suggesting that snakes had undergone habitat differentiation and geographic radiation by the mid-Jurassic. Phylogenetic analysis of squamates recovers these early snakes in a basal polytomy with other fossil and modern snakes, where Najash rionegrina is sister to this clade. Ingroup analysis finds them in a basal position to all other snakes including Najash . The origin and evolution of snakes remain poorly understood. Here, the authors show that fossils previously described as anguimorph lizards are ancient snakes and demonstrate that they share features with snakes and lizards, which suggests great diversity of snakes by the Jurassic period.
ISSN:2041-1723
2041-1723
DOI:10.1038/ncomms6996