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Sand Lizard Sexual Dimorphism? |
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-LAF
Senior Member Joined: 03 Apr 2003 Location: United Kingdom Status: Offline Points: 317 |
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Posted: 23 Jul 2003 at 10:05am |
I've just been going through some recent photographs to construct head scale maps for the sand lizard and I've noticed something a little odd. My female sand lizard has no frontonasal, the prefrontals join straight onto the (large) supranasals. My male has either a split pair of prefrontals or a split frontonasal, either way he appears to have a pair of frontonasals.
Female: Male: Sorry about the poor quality of the photos but I was handholding at 600mm with a full set of extension tubes so the ISO was pushed up to 400, and I'm afraid depth of field was a still little compromised Does anyone know if these differences are due to sexual dimorphism (males do seen to have longer, pointier heads) or are simply an example of the natural variation that can occur in either sex of this species? Any ideas would be appreciated. Mnay thanks, Lee. |
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Lee Fairclough
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-LAF
Senior Member Joined: 03 Apr 2003 Location: United Kingdom Status: Offline Points: 317 |
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Hi Dave, thanks for that, I have checked my other photos and the only two where anything is discernible show another female (a fair bit bigger than, but basking only inches away from, the one shown in my post) that also had no frontonasal, and a male (from a different site) which appears to have a sigle (intact) frontonasal. Likewise Tony's male on the ID pages of this site has a single frontonasal. I have found no reference to this in any books.
Out of interest, the picture of a female sand lizard in Beebee & Griffiths is a bit too small to see head scales on, but if anyone has the softback that picture is much larger on the front? If anyone has this would they see if there is a frontonasal present on that female? Pleasse? Would be interesting to know if presence/absence of frontonasal(s) would be a way to distinguish the sexes, and if my my paired frontonasal male is a normal occurence or just another mutant (a la my V. ursinii wannabe adder). Cheers, Lee. |
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Lee Fairclough
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Admin Group Joined: 01 Jan 2007 Status: Offline Points: 10 |
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Hi Lee, The photo on the front page cover of Beebee and Griffiths seems to show an unsutured frontonasal. Sorry no scanner at moment |
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administrator
Admin Group Joined: 01 Jan 2007 Status: Offline Points: 10 |
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Lee, I've managed to photograph the image, bit blurry but good enough to see it I think, I'll mail it to you as I have no copyright permission to publish it on RAUK. Edited by administrator |
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-LAF
Senior Member Joined: 03 Apr 2003 Location: United Kingdom Status: Offline Points: 317 |
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Thanks for that Gemma, it looks like there's just a lot of natural variation then (although both females I saw without frontonasal were basking together, so maybe they were related?). I'll see what other people turn up as well but I suspect that I'll have to say frontonasal may be present, absent, or there may even be two. Which is quite a lot of variation!
Thanks again, Cheers Lee. |
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Lee Fairclough
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