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Desert Diary
Amphibians and Reptiles/Legless Reptiles

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Everyone knows how to tell a snake—it doesn't have any legs! Just goes to show that what "everyone knows" requires a bit of skepticism. It's true that snakes don't have legs, but neither do some lizards and some amphibians. I can almost hear it now: "But if it's a reptile and doesn't have legs, it really has to be a snake." There's another bit of folk advice here that's apres pos: "Don't judge a book by its cover".

Biologists long ago learned to look deeper. After all, we classify organisms by their evolutionary relationships, not looks alone. Strip off the flesh of a lizard's head, and we have a quite solid skull and jaw. Do the same thing to a snake, and we're practically dealing with a mobile. An absent stabilizing bar of bone, movable skull bones, and extraordinarily loose joints interact to allow snakes to swallow prey bigger around than their heads—something you'll never find a conservative lizard trying. Relax, though—our Chihuahuan Desert lacks legless lizards and amphibians—if it doesn't have legs, it's a snake! pen and ink

 

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Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.

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European Glass Snake

European Glass Snake. Note the ear opening, which will separate these lizards from snakes (as will eyelids). Photograph by John White.

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References

Conant, R. 1958. A field guide to reptiles and amphibians. Houghton Mifflin Co., Boston. 366 pp.

Web Resources

Ophisaurus attenuatus, Illinois Natural History Survey.

Ophisaurus attenuatus, University of Michigan Museum of Zoology.

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