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5145 Views 22 Replies Last post: Oct 23, 2012 9:44 PM by Robert Randell RSS
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Apr 20, 2011 1:53 PM

Marks on Chalk, looks like fossil skin?

This fragment of what looks like skin, about 20mm long, was in chalk near Pitstone Quarry in the Chilterns. The photos are pretty awful I'm afraid (new camera, old photographer!), but you can just about see the scales/plates in the close-ups. Any suggestions please?

 

skin 3.jpg

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    Mar 15, 2011 10:35 AM (in response to JohnT)
    Re: Skin?

    Hi,

     

    I really can't say anything for certain from the photographs, which as you suspect, are just not high enough quality.

     

    It does look though, that this is an area of mineral growth, probably calcite, upon the Chalk surface, rather than fossilised skin. Calcite growth on Chalk is common. Fossilised skin is only found in rare and exceptional conditions as it is fragile and gets destroyed before preservation. No soft parts like skin have been found in Chalk. The Chalk was laid down in quite a deep sea in the Cretaceous period and even hard parts of vertebrates, especially terrestrial vertebrates, are rare in the Chalk.

     

    Please email ias2@nhm.ac.uk if you would like to bring or post it in to the museum for examination to confirm the ID.

     

    I hope this helps a bit!

     

    Luanne

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    Mar 15, 2011 10:47 AM (in response to JohnT)
    Re: Skin?

    This is a good website, and has some pictures of calcite crystals in Chalk:

     

    http://www.chalk.discoveringfossils.co.uk/Chalk%20Group.htm#calcite

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    Jul 7, 2012 11:34 PM (in response to JohnT)
    Re: Marks on Chalk, looks like fossil skin?

    Hi John.

     

    Only just noticed this post,

     

    This i am certain is fossil shark cartilage with what looks like a few dermal denticals scattered about the surrounding chalk.

    So you were not that far of the mark by thinking it was skin!

     

    Cheers

    Keith

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    Sep 2, 2012 11:55 PM (in response to JohnT)
    Re: Marks on Chalk, looks like fossil skin?

    Hi John,

     

    Just noticed this thread.  As per Keith's and Brett's comments, Chalk shark remains of this sort, preserving the calcified cartilage, are scarce, and it would be very good to establish which species this is and how much of the body is present.  The majority of Chalk sharks are known from teeth only, so potentially this could be an interesting or important specimen.  Are there any teeth associated? (these could be very small).

     

    Are you able to post some more pictures of the full specimen and counterpart?

     

    If your specimen is from the Lower (Grey) Chalk, then the majority of known well-preserved skeletal material is from Synechodus & Heterodontus:

    http://www.chalk.discoveringfossils.co.uk/5%20Synechodus.htm

    http://www.chalk.discoveringfossils.co.uk/5%20Heterodontus.htm

     

    Best regards,

     

    Robert

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          Sep 20, 2012 9:48 PM (in response to JohnT)
          Re: Marks on Chalk, looks like fossil skin?

          Hi John,

           

          Thanks for posting the extra images.

           

          The British Geological Survey have an excellent tool for investigating local geology:

          http://mapapps.bgs.ac.uk/geologyofbritain/home.html

          It looks like the Pitstone area is in the Grey Chalk, but I may be looking at the wrong pit.  Have a look and see what you think.


          I agree that the vertebrae don’t look much like Heterodontus, or Synechodus, so that appears to discount the more ‘common’ smaller Grey Chalk sharks (in terms of preserved cartilage).  You can see from this page that there is variety in vertebrae form between different groups of shark, with only figure 6 looking similar to yours:

          http://www.chalk.discoveringfossils.co.uk/5%20elasmobranch%20vertebrae.htm

           

          A shark this small could have some miniscule teeth and it is possible there are some teeth present amongst the microscopic debris.  Do you have a microscope available to check this out?

           

          Best regards,

           

          Robert

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                Sep 24, 2012 9:32 AM (in response to JohnT)
                Re: Marks on Chalk, looks like fossil skin?

                Hi John,

                 

                Excellent work finding that tooth - I wonder if there are anymore?

                 

                My first thought is that this is Scyliorhinus (dogfish/cat shark) which would fit well with the small size and also the vertebrae form.  There are a couple of examples with cartilage preserved here:

                 

                http://www.chalk.discoveringfossils.co.uk/5%20Scyliorhinus.htm

                 

                Would you mind if I added some of your images to the Chalk Fossils website (credited to you of course)?

                 

                Best regards,

                 

                Robert

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                    Sep 24, 2012 10:46 AM (in response to JohnT)
                    Re: Marks on Chalk, looks like fossil skin?

                    hi i have or had a similar fossil from the brick pit Ockly in Keny an outline of fish with verterbra /scales/ etc .. on iron clay th fish is outlined in the clay ie the soft parts Its really an amazing find .... Maybe donate it too a museum ??? plus amazing close up of the tooth ,,...

                     

                    PS look at the exellent shark  tooth  from chalk near your find .....posted here....

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                    Oct 1, 2012 11:00 PM (in response to JohnT)
                    Re: Marks on Chalk, looks like fossil skin?

                    Hi John,

                     

                    Interesting that the new teeth are poking through the cartilage.  Could this mean that they are in life position?  It would be great to see some close up shots of these.

                     

                    It would probably be worthwhile to draw a circle (1cm diameter, on the Chalk matrix) with pencil around the first tooth you found, so that people who study this piece in the future don't overlook it.

                     

                    We need to think about what species you have found.  One of the values in finds like yours is that it can show the different forms/shapes of teeth that belong to a particular species and helps to confirm that they belong to a single species rather than multiple species.

                     

                    Best regards,

                     

                    Robert

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                      Oct 2, 2012 11:33 AM (in response to Robert Randell)
                      Re: Marks on Chalk, looks like fossil skin?

                      Hi John,

                       

                      Charlie Underwood, an expert in these matters, has kindly looked over the images.  Response as follows:

                      'That is a nice lower jaw and tooth. It looks like Scyliorhinus brumarivulensis Underwood and Ward 2008 which is very common' [isolated teeth] 'in the Santonian-Campanian. There is a similar species in the Cenomanian' [need to check if that has a name]. 'There are 2 species ("S". dubius and "S". antiquus ) known from similar tooth scatters/bits of cartilage from the Cenomanian but this does not look like one of them (although a juvenile of female S. antiquus could possibly have teeth like that)'.

                       

                      So, this could be the first recorded find of this type of scyliorhinid with associated teeth and cartilage and it certainly has some scientific interest.  It would be great if this found its way to a museum one day.

                       

                      Best regards,

                       

                      Robert

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                          Oct 23, 2012 9:44 PM (in response to JohnT)
                          Re: Marks on Chalk, looks like fossil skin?

                          Hi John,

                           

                          It looks like you are making excellent progress with that very fiddly prep job.  Very well done on finding the second tooth.  I will hold off on getting anything online until the prep is finished, which may of course take a while as you seem to be working suitably slowly and respectfully on this.  [It often helps to use a very small short-bristle water colour brush with a drop of water to 'brush' away the final dusting of matrix on small fiddly Chalk fossils like this].  Please keep us posted on progress.

                           

                          Best regards,

                           

                          Robert

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