title: Molecular evidence for a terrestrial origin of snakes.
abstract: Biologists have debated the origin of snakes since the nineteenth century. One hypothesis suggests that snakes are most closely related to terrestrial lizards, and reduced their limbs on land. An alternative hypothesis proposes that snakes are most closely related to Cretaceous marine lizards, such as mosasaurs, and reduced their limbs in water. A presumed close relationship between living monitor lizards, believed to be close relatives of the extinct mosasaurs, and snakes has bolstered the marine origin hypothesis. Here, we show that DNA sequence evidence does not support a close relationship between snakes and monitor lizards, and thus supports a terrestrial origin of snakes.
authors.affiliation: NASA Astrobiology Institute and Department of Biology, 208 Mueller Laboratory, Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Vidal
authors.forename: S Blair
authors.initials: SB
authors.lastname: Hedges
mesh_terms: D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D004777:Environment; D016654:Genes, RAG-1 / Q000235:genetics; D016258:Genes, mos / Q000235:genetics; D016013:Likelihood Functions; D008116:Lizards / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012911:Snakes / Q000235:genetics*