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1278 Views 9 Replies Last post: Jan 24, 2013 7:50 PM by Ivan RSS
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Jan 22, 2013 4:37 PM

What fossil is this

This was found in Ireland county wicklow. The rock is fairly soft.

Is it a fossil and if so how old is it roughly?

 

Thank you in advance

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      Jan 23, 2013 1:05 PM (in response to Ivan)
      Re: What fossil is this

      Ivan,

      My initial reaction is belemnite or crinoid, but we could really do with seeing things in cross section. Can you see what the fossils look like on the sides of your specimen? If they do not show up there, you try breaking the specimen carefully, perhaps near an edge. Either way, the fossils may appear almost identical to the host rock, so near-impossible to see - but it really would help to try...

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          Jan 23, 2013 2:04 PM (in response to Ivan)
          Re: What fossil is this

          Interesting - I see cross-sectional shapes that are triangular, square, rhombic, and irregular.

           

          I see no rings (belemnites can show rings depending on where they are interescted),

          and if they were crinoid, I would expect them to be near-circular, and we should have seen segmentation in the long section.

          I think the cross-sectional shape and overall elongation rules out fish scales.

           

          Hmmm... Part of me wonders about metamorphic minerals; also, echinoderm spines (can't remember having seen them with faceted sides). I'm open to other suggestions...

           

          Ivan,

          Is there any chance of you cutting a cross-section of one/some, wetting/varnishing it, and using a hand lens to look for internal structure and/or posting a close-up photo?

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            • Currently Being Moderated
              Jan 23, 2013 9:53 PM (in response to Ivan)
              Re: What fossil is this

              Hi Ivan,

               

              One of the hardest things when answering questions here is knowing the level to pitch them at - through not knowing the inquirer. But we usually get there, perhaps making a few imperfect assumptions along the way. So thanks for clueing me in about yourself a little.

               

              Ideally, you need a lab, but even a well equipped lab will be missing some expensive apparatus. Almost all of us have to make-do. That also forces us to be inventive and think laterally. You have not been stretched yet, but you have made a promising start. So far in your geological career, you have:

              • seen some things that looked interesting,
              • allowed your curiosity to drive you to do research to identify them (the crinoid and bryozoan) and find out more about them,
              • been able to find somewhere to enquire when you want to know more.

              Curiosity, ability to research, and collaboration are vital assets for a scientist.

               

              In your postings here, you also demonstrate: good writing skills (use of comma and hyphen, capitalization of initial of Bryozoa, etc.) and consideration for others ('Thank you in advance'). Your writing indirectly informs your readers about yourself and in so doing engenders effective collaboration. All good stuff.

               

              Now, in the current instance:

               

              1. Take more photos (more close-up) of your specimen now - while it is still intact.

              2. Break the stone across the middle, as cleanly as you can. You might need a cold chisel and hammer (ideally wear protective specs).
                Can you see structure within the dark objects? You will probably need to use a hand lens (x10 or more).
                If not, or in any case, wet the surface and look again.
                You may have seen useful detail; if so: take close-up photos if you can.

              3. You say the rock is fairly soft.
                If possible, scratch away at the rock to liberate one or more of the fossils, obviously trying not to damage it. It would be useful to know the overall shape. (The other observations we're trying to make (on the flat side and on the edges) are an indirect way of ascertaining the same thing.)

              4. Report back here with a description and maybe those photos.

              5. Send me an email.
                I can give you a suggestion, but it would be unwise of me to do so in open forum, because it is potentially dangerous (and I can't be sure who might follow the suggestion), because it cannot be endorsed by the Natural History Museum (with which I am not affiliated), and because I need to ensure that if you follow any of the suggestions, you must do so entirely at your own risk.

               

              Regards,

              Mike

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