Re: Snake Origins

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: : ...I've never really thought that "ignorance is bliss", but it sure does make for simple answers. When I first learned about Life there were just two kingdoms: plants and animals. Simple. Ignorant. : : ...Until very recently I was as ignorant of the phylogenitic origens of snakes as Old Carl was of Protista. My (mis)conception was that from an ancestral lineage, there was a split, with snakes going one way and lizards the other. I think this was aided by the Serpentes/Lacertilia classification convention that seemed to make the two equal. Simple. Ignorant. : : ...I guess you herpetologists have known for a number of years that this was false. I read now that "snakes are paraphyletic with regard to lizards", and that "snakes are nested within the lizards." This means that a number of lizard lineages (clades) evolved first; from one (or more) of those clades snakes evolved, radiated into a number of species, and now stand beside (para=beside) the decendants of the clades that gave rise to them. Right? I can't believe that all of the extant Serpentes came from a single branching. I mean, blind snakes have one lung developed and the other lost, while in the rest of the Serpentes it's the other way around. Seems like a preeety fundamental diference to me. So how many clades of lizards gave rise to snakes? Which ones to which snakes? : All the avialble evidence suggests that snakes are monophyletic. The currently best supported hypothesis of relationships suggests that snakes are the sister group of the Mosasaurs, a group of large aquatic lizards that became extinct at the end of the Cretaceous. The snake+mosasaur clade appears to be the sister clade of Varanids+Lantanotus. : The most recent reference is: Lee, M.S.Y. (1998) Convergent evolution and character correlation in burrowing reptiles: towards a resolution of squamate relationships. Biological Journal of the Linnean Society 65: 369-453. : : Cheers, : Wolfgang

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