Why is a slow worm NOT a snake?

[Paul mabbott]

Snakes still have some leg bones although these are obviously non-functional. Clearly their ancestors were legged. This is fascinating suggesting that some early 'snakes' had one pair of functioning legs:
Digimorph - Pachyrhachis problematicus (fossil snake with legs)

Might they have derived from something like the upright lizards? Losing the need for forelimbs and later, retreating under rocks, losing the need for hind ones? Probably leg loss happened several times under different pressures.

[Meta menardi]

Originally Posted by Paul mabbott

On the other hand wait a few years for enhanced localised global warming and the south may be a desert ... might be a better gamble to sit and wait for the dry heaths to reach you?

Paul, you make me nervous, I miss the Avatar. I have always bought houses at the top of hills

1: Because all the cheap secondo cars I bought had a need for some... gravity... in the mornings.

2: Nicer view.

3: Scared of water unless it is outside a Colossal boat and I am inside.

[Goatboy]

This is one of those questions that at first make you go "Doohhhh", then when you think about it, my level of understanding is about "well, because someone told me so".

I was very much aware of that when I started this thread.

Thanks for the heads-up on Cladistics. I'll have a look for something this weekend and post a link if I find anything interesting.

[smileysnake]

The simple, and perhaps slightly curt, answer to your question is that of course it is a lizard! But this you already knew. The classification of lizard however doesn't necessarily include the presence of legs, as there are numerous legless lizard species around the world. In fact the legless characteristic is really the ONLY thing that snakes and these lizards have in common.

Visually of course a slow worm is very snake like, and until you start looking closely many would assume it is a snake. As you rightly say, one difference is the presence of eyelids, but beyond this the skin structure is very different, with many small uniform scales, unlike the large (especially on the underside) and small scales found in snakes. Internally of course the skeletal structure, and the arrangement of the internal organs, easily differenciates the two animal types.

The skeleton of some snakes does indeed retain vestiges of rear legs. In many this is simply a vertabrae in the lower body which could be the remains of a pelvic bone. In others, specifically the larger Boas and Pythons, there is a small pair of claws, or spurs as we call them, either side of the vent (bottom). We often use these as a quick method of determining sex, as the males spurs are larger than the females. The same is found in some turtle species with the front claws.

Of course it is not always so easy to define a species. Recently a new Cobra species was 'discovered'. It was always regarded as a sub-species, but a DNA test showed it to not be biologically related, and so it was reclassified.

[demicav]

Originally Posted by smileysnake

The simple, and perhaps slightly curt, answer to your question is that of course it is a lizard! But this you already knew. The classification of lizard however doesn't necessarily include the presence of legs, as there are numerous legless lizard species around the world. In fact the legless characteristic is really the ONLY thing that snakes and these lizards have in common.

Visually of course a slow worm is very snake like, and until you start looking closely many would assume it is a snake. As you rightly say, one difference is the presence of eyelids, but beyond this the skin structure is very different, with many small uniform scales, unlike the large (especially on the underside) and small scales found in snakes. Internally of course the skeletal structure, and the arrangement of the internal organs, easily differenciates the two animal types.

The skeleton of some snakes does indeed retain vestiges of rear legs. In many this is simply a vertabrae in the lower body which could be the remains of a pelvic bone. In others, specifically the larger Boas and Pythons, there is a small pair of claws, or spurs as we call them, either side of the vent (bottom). We often use these as a quick method of determining sex, as the males spurs are larger than the females. The same is found in some turtle species with the front claws.

Of course it is not always so easy to define a species. Recently a new Cobra species was 'discovered'. It was always regarded as a sub-species, but a DNA test showed it to not be biologically related, and so it was reclassified.

Very interesting post Smileysnake. Welcome to WAB.

[murraytunes]

Brecon Beacons - I thought this was a snake at first but it does seem to be one of our little wormy friends. My two year old daughter calls worms "Lady Gaga's" for some reason!
‪Slow worm on the Brecon Beacons South Wales‬‏ - YouTube