Skip navigation
2477 Views 24 Replies Last post: Oct 30, 2013 3:24 PM by MikeHardman RSS
Currently Being Moderated

Jul 17, 2013 1:28 PM

Can anyone identify this fossil please?

I discovered this fossil when walking my dog on common land in Surrey. - It was just laying on the surface of the path. - Approximately 70mm in diameter.

Attachments:
  • Currently Being Moderated
    Oct 30, 2013 3:17 PM (in response to Alex and Singha)
    Re: Can anyone identify this fossil please?

    Alex & Singha,

     

    It is an internal mould of a bivalve (a bit like a cockle).

    As internal moulds go, your specimen is moderately distinctive, but I still can't put a name to it.

    If you told us whereabouts in Surrey, that would help .

     

    Mike

    • Report Abuse
  • Currently Being Moderated
    Aug 12, 2013 12:23 PM (in response to Alex and Singha)
    Re: Can anyone identify this fossil please?

    Hi Alex and Singha,

     

    Fossil moulds of bivavles bivavle puzzled early naturalists. This preservational style is common in species of bivalves that had aragonitic shells. Unlike the more stable calcite shell found in oysters, araonite is routinely dissovled by pore waters passing through the rock, leaving spaces where the shell was formerly located surrounding hardened sediment core. The core is an internal mould, oftern known by the German name 'steinkern'. Steinkerns are solid objects that may fall out of the rock cleanly when it is broken open.

     

    http://www.nhm.ac.uk/nature-online/earth/fossils/fossil-folklore/fossil_types/bivalves02.htm

     

    I hope this is interesting to you,

    Thank you for your post,

    Fiona

    • Report Abuse
    • Currently Being Moderated
      Sep 28, 2013 3:15 PM (in response to Alex and Singha)
      Re: Can anyone identify this fossil please?

      It could possibly be a fossilised cockle shell. I used to have a few of these as a kid and I seem to remember that's what it was. I'm not an expert so just a guess at the moment from me.

      • Report Abuse
        • Currently Being Moderated
          Oct 30, 2013 3:19 PM (in response to Alex and Singha)
          Re: Can anyone identify this fossil please?

          Alex & Singha,

           

          Great stuff!

          Persistence pays off!

           

          I think this is looking like one of the possibilities I mentioned earlier - Cardita planicosta, now called Venericor planicosta.

          Here's a super example from the Bracklesham Beds, Bracklesham, Hampshire.

          http://www.fossilsdirect.co.uk/gallery_details.cfm?prodref=SP958

           

          If you look here, you'll see both the whole fossil and an internal mould

          http://www.dmap.co.uk/fossils/bracklesham/biv/brackbiv.htm.

          (search for 'Venericor planicosta', it'll be near the middle of the (long) page)

          I think you'll agree the internal mould matches yours quite well.

          So I think that is a reasonable ID, at least for now.

           

          Both of those sites focus on the Bracklesham Beds, which is in the middle of the Bagshot Formation (mentioned earlier), stratigraphically speaking.

           

          You will also find another pre-mentioned possibility on the brackbiv.htm page - Glycymeris pulvinata

          (called Pectunculus pulvinatus in the old print I was referring to at the time). If you compare the two, you'll see how different they are in terms of their hinge dentition. That's an important factor in discriminating between candidates when trying to ID bivalves.

          So "your mission Jim – should you choose to accept it…”, is to find an specimen that shows not just the shell but the hinge dentition!

          I know I am asking a lot!

           

          Maybe that will point to Venericor planicosta, or to Glycymeris pulvinata, or to something else (see that brackbiv.htm page again).

          We then have to be careful. Just because we ID one specimen as a particular species, that doesn't mean the other specimens are the same species; you could be collecting multiple species. It is common for fossils to occur in assemblages. We'll cross such bridges if and when we come to them.

           

          Keep up the good work; keep looking!

           

          Mike

          • Report Abuse
            • Currently Being Moderated
              Sep 30, 2013 6:03 PM (in response to Alex and Singha)
              Re: Can anyone identify this fossil please?

              Hi Alex,

               

              Well, since you're the expert on these now, you have to do the hard stuff - so your groupies will be really impressed!

               

              It may be off-topic, but I'd really quite like to see a photo of Singha, and preferably while she's sniffing out a bivalve, or holding such a find proudy in her mouth. (I don't suppose there's such a breed of dog as an oyster hound?!)

               

              Mike

              • Report Abuse
            • Currently Being Moderated
              Oct 5, 2013 10:25 PM (in response to Alex and Singha)
              Re: Can anyone identify this fossil please?

              Hello Alex and Singha

              A few images of the fossils similar to what created your negatives.

              Good finds well done and keep them coming.

               

              Tabfish

              Attachments:
              • Report Abuse
              • Currently Being Moderated
                Oct 30, 2013 3:24 PM (in response to Tabfish)
                Re: Can anyone identify this fossil please?

                -- this is intended as a temporary posting --

                 

                Stupid me, I originally used the term 'internal cast' in this thread, where I should have been using 'internal mould'. I have edited my posts correcting those mistakes.

                Please could other folks who have posted in this thread edit their posts to change 'cast' to 'mould'.

                 

                ...This being in the best interests of people reading the thread in future - so as not to lead them into making the same error as me!

                 

                I apologise for the mix-up.

                 

                Mike

                • Report Abuse

More Like This

  • Retrieving data ...

Bookmarked by (0)

What the symbols mean

  • "correct" answer available
  • "helpful" answer