A few of my favorite snake and snake-like pictures from California

[Fieldnotes]

<img src='http://elib.cs.berkeley.edu/imgs/512x768/0000_0000/0403/0396.jpeg'>
Western Diamond-backed Rattlesnake (Riverside Co.)

<img src='http://elib.cs.berkeley.edu/imgs/512x768/0000_0000/0504/0819.jpeg'>
Nevada Shovel-nosed Snake (Inyo Co.)

<img src='http://elib.cs.berkeley.edu/imgs/512x768/0000_0000/0504/0808.jpeg'>
Southern Rubber Boa (San Bernardino Co.)

<img src='http://elib.cs.berkeley.edu/imgs/512x768/0000_0000/0404/0139.jpeg'>
Black Legless Lizard (Monterey Co.)

[Davey312]

How come that legless lizard isn't classified as a snake? It has the same body structure. Does it have to do with the placement and function of the organs or something? Also are those lizards able to stretch like a snake does?
Thanks,
Davey

Edit: forgot to mention... SWEET PICS! lol must have been fun finding all of them.

[ydnic]

They really in a different family than snakes (obviously) and they still have remnants of a hipbone and bits of hind legs. They can move about like a snake, but they can drop their tail which i believe is mid point on the body.

[Removed_2815]

Most legless lizards have moveable eyelids and external ear openings. They have rigid jaws (unlike a snake's flexible jaws) and broad, fleshy tongues (unlike a snake's forked tongue). Most snakes have single rows of wide scales along their belly whereas legless lizards have the same pattern of scales over their entire body. There are more differences that I could go into.
Ryan

[K1LOS]

Do they suggest that Lizards evolve into snakes?

Geoff

[Fieldnotes]

Not only suggest, but is fact..........Answer YES

[JD@reptiles]

i think i am going to head back to california for some herping. i was in San Bernardino with BWSmith and found a california king snake :P

[Ontario_herper]

That D-back is sweet!

[monitor12345]

how do you suggest its a fact? a snakes internal organs ar moved different than a leggless lizard, their jaw also unhinges and the snake has a tubelike structureinside their mouth that they stick on the outside of their mouth when they eat so they can breathlegless lizards dont

[K1LOS]

so does that mean that monitor lizards are furthest along with that progression then? Many have long slender bodies, and all have the forked tongues. Do they have a jacobsons organ though?

Geoff

[Removed_2815]

Originally posted by monitor12345
how do you suggest its a fact? a snakes internal organs ar moved different than a leggless lizard, their jaw also unhinges and the snake has a tubelike structureinside their mouth that they stick on the outside of their mouth when they eat so they can breathlegless lizards dont

So this is your immalleable proof that suggests snakes did not evolve from lizards?

Yes, snakes evolving from these saurian tetrapods is evolutionary and genetic fact (as much as these scientific doctrines will allow). The only real question was whether snakes evolved from land-based or aquatic lizards.
There's very recent genetic evidence that strongly suggests that snakes evolved from land-dwelling lizards.
Many people erroneously believed the aquatic-lizard to snake theory because of morphological similarities between monitors (the closest relatives to mosasaurs - a giant, extinct aquatic lizard that is the only known marine lizard living at the time that snakes evolved) and snakes. A comparison of the DNA from 17 of the 25 known families of snakes to DNA from all 19 families of lizards was completed by Vidal and Hedges (2004). They discovered that snakes were much more similar to land-based lizards than to monitors, thus providing strong evidence for terrestrial evolution (Vidal and Hedges 2004).
The results clearly show that there is no relationship between monitors and snakes. The superficial similarities between monitors and snakes (e.g. forked tongues, etc.) may just be an example of convergent evolution.
The exact point in evolution where snakes separated from terrestrial lizards has not been determined (as far as I know) but the question of whether snakes evolved from lizards is a non-issue.
Have a look at the published literature for more information as it's a little bit beyond the scope of a public forum.
Cheers,
Ryan

[K1LOS]

neat, thanks RMBolton. Can you recommend any specific titles?

Geoff

[Removed_2815]

Here is the article by Vidal and Hedges that I was referencing. There are some good leads to other papers in the literature cited section.
Cheers,
Ryan