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Post Options Post Options   Thanks (0) Thanks(0)   Quote administrator Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 8:26am

Hi Steve, you know I was just contemplating this, it would be really useful to exchange some examples and try and work out the labelling.

Follow the link in my first post if you haven't yet seen Bensons' examples, which will shed some light. 

I think I'm going to need to do a bit research regarding the naming of head scales, before I can group them. I'm sure I've labelled my diagram wrongly, the top "2" looks OK as an internasal, the other "2"s look like they should have been labelled as prefrontals and therefore should have been "3"s - group 6 I haven't a clue what you would classify them as.

The only reference I have at the moment is Smith, The British Reptiles and Amphibians, where scalation of a grass snake is given, so I'm struggling a bit at the moment! If anyone has any other sources for preferably V.b head scale nomenclature it would be of great help.

Just for fun I make Biggie

7281?(I'm not sure yet which is group 5)92

On the bright side I did realise whilst sitting at the dentist this morning there is a catch all, if the groups are consistently labelled the odd labelling mistake isn't the end of the world as you could still test for n, total number of scales for labelled groups, i.e. from my reckoning Biggie would have n = 7 + 2 + 8 + 1 + 9 + 2 = 29 though the matching set will probably be larger particularly for numbers close to the mean, it does allow for some further checking if there no immediate match.

I'm off to scrutinise Benson's examples a bit more, though the web images are a bit blurry. If anyone has the original paper to hand.. beg beg beg beg

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Vicar Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 8:40am

ROFL!

I made it 6441082, and I have some head shots here, where I don't even know where to start!...OK  I'm researching too :P

Steve Langham - Chairman    
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Vicar Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 8:47am

this webPage looks familiar , and could help some.

http://www.onewildworld.co.uk/reptiles/viperaberus.htm

Steve Langham - Chairman    
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Post Options Post Options   Thanks (0) Thanks(0)   Quote administrator Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 9:12am

Well it wasn't a bad start at least we agreed on the number of parietal scales ,

Thanks for that link, I had a sneaking suspicion Lee's site might be holding some gems and 'twas my next port of call.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote administrator Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 10:37am

Steve, I've taken a look at Benson's paper again. It appears to give two examples for the method of coding the scale groups, though it also appears one of these is spurious.

Taking the one good example I've produced the following Figure, (named After Benson as though it is a complete rework of the given information I don't want to run into a copyright issue)

My next step is to recode my original example following this, then I'll have another go at 'Biggie'. At least I now know why I was confused by group 5 and group 6.

 

It seems at this stage that it is more important to define the numbered groups by their ease of grouping from a dorsal head photograph, than worry too much about nomenclature for individual shields or scales.

I think if we could produce a dozen or so standard reference figures like the one above it will all start to get a lot easier.

 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote administrator Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 11:37am

Another, this time adapted from a third, graphical explanation, of the method from Benson's paper.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote administrator Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 12:06pm

OK my original example reworked.. with some different numbers

This one threw me a bit, I had a lot of trouble deciding which scales belonged in group 3 and group 2. I used the logic that the ones marked in red (group 3) qualified by either

a) They were directly adjacent to the frontal (group4), or

b) They were directly adjacent to group 5 or group 6

If anyone knows Paul Benson and could direct him towards this thread. I think we would all be forever grateful.

 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote administrator Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 1:34pm

And here is Biggie,

To the above rules I've added (I almost typed addered then, time to stop working me thinks) the further rule:

c) To qualify for group 5 and group 6 the scale must be directly adjacent to either the left or right supraocular

This gives following each of the three rules stated so far:

 

Of course this only my interpretation of the method, but by forming some guiding rules I've found it is easier to form the groups without too much subjectivity.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Vicar Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 1:54pm

I was going to suggest that maybe the frontal count on 'Biggie' was 2 ? Just been having this conversation here, I have seen examples where there is no obvious frontal at all, just split into many smaller scales ?

Are you thinking its OK to have blanks ?, or do we need to account for all the major head-scales ?

Doesn't really matter what was originally intended, although it would be better to have universal agreement, but spot on Gemma, we do need a good set of definitions for each group.

Where's David Bird when you need him ? :P

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Post Options Post Options   Thanks (0) Thanks(0)   Quote administrator Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 2:36pm

The blanks were my first stumbling block, at first it didn't seem rigorous to leave blanks.

The trouble is it starts to get complicated to form the rules if all scales are to be counted. It is also easier and quicker not to have to classify all the scales that are present (don't forget I've an engineering background and am inherently lazy) Also idealy for the code we want the scale group counts to be no larger than 9 else more problems start to occur.

The primary concern is to be able to form the groups consistently i.e. to have a foolproof method that different workers can reproduce over and over and that can be easily learnt.

I really like the idea that someone could go to a site I visit regularly (which happens) then call me up and say, "I had a 6231442 today, do you have any record match". I then find 3 possible matches and we compare photographs for a final ID.. that would be really great!

Take for example one with dozens of broken up scales, it won't happen that often. So if you code using the rules only a few of the scales need to be looked at saving a lot of work. OK there will be lots of blanks, but at the end of the day we just want to grab some likely fits from a large record set, the final ID will be scrutiny of photographs, scale group counts, head patterns and also the way the scale groups are arranged and the way individual scales are marked. All will be added together for a final ID.

I'm considering for example dropping rule (b). Is it needed? OK you get more blanks, but rule (a) alone would still give reproducible results, i.e. all workers would have recorded 3 scales in group 3 for my own example based on rule (a).

Regarding 2 frontals for Biggie, my logic says that frontals are most often one large scale, maybe 2 or 3.. the small fragmented scale is an anomaly that is best ignored when forming the scale groups but is very useful if highlighted on the ID card as an identifying feature in the way that you have Steve. (I hope that is what you ment and I've not missed a joint line in the frontal)

I have for one of my working codes P! which simply draws my attention to the parietal scales of the individual as they have distinctive markings. Biggie could become F!6251242 for example?

We need more examples come on all those watching this thread, your dying to give it a go to, post up your results

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