Hmmmm????

Discussion in 'Cephalopod Fossils' started by Terri, Oct 5, 2011.

  1. Terri

    Terri Sepia elegans Registered

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    A friend of mines 8 year old son found this in a creek bed in Sumner Co. He's very interested in my fossils and thought I would like it and wanted to know what it was. I don't have the coordinates but looking at the geology of Sumner co. it could be anywhere from middle Ordovician to Devonian, from what I could find though I think the Devonian outcrops are farther north towards the Kentucky border so probably Ordovician. At first I was thinking concretion? Or sponge? :smile:
     

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  2. CaptFish

    CaptFish Colossal Squid Staff Member Moderator

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    it's a prehistoric Easter-egg!...good hiding spot
     
  3. Terri

    Terri Sepia elegans Registered

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    :lol: He's a pretty smart kid, don't think he'll buy into that! :heee:
     
  4. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    It looks like a river rounded rock with an inclusion of something harder. Is the inclusion made of chert? Does it stick out the other side? The inclusion may be a fossil, but the rest of the rock looks like limestone. We need to see more to determine any kind of ID. Very neat looking rock though. :smile:
     
  5. Terri

    Terri Sepia elegans Registered

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    I don't know if it's chert, but it does seem to be a harder and more smooth material than the matrix, how would I determine if it's chert? The rock is broken on the other side I'll have to get pictures tommorrow, no it doesn't stick out the other side. There are some vague rings where you would think the fossil(?) runs through the rock. I'll post pics. tommorrow. Thanks Kevin :smile:
     
  6. Terri

    Terri Sepia elegans Registered

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    I don't know if this will help or not....
     

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  7. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    I can see that whatever it is, is cylindrical and goes through the rock. I'd like to say it's a cephalopod, but without a view of any septa or siphuncle it will remain a mystery. :hmm:
     
  8. Terri

    Terri Sepia elegans Registered

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    It does remind me a lot of the mysterious "round things" in post #333 in the Ordovician thread, with a different mode of preservation. :bonk:
     
  9. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Kevin,
    I am assuming the limestone built up over the "round thing". If you tapped it with a hammer, hard enough to break the limestone (not suggesting you do this Terri :grin:) what are the chances that it would expose the proposed fossil in tact? I am assuming that limestone is relatively soft and the fossilzed animal relatively hard of course which may be way off the mark.
     
  10. Terri

    Terri Sepia elegans Registered

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    D, I have access to a saw, I just don't have experiance with using them. It should be pretty easy to slice the thing, I'll just have to wait for help with it. I would like to know though exactly where I should slice it to see what we need to see (Kevin?).

    After doing a little reading, I think the "inclusion" is chert.
     
  11. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    Looking at this enlarged photo I would say there is not a good chance. There is no clear contact between the fossil and the matrix, the conchoidal fracture goes across both the fossil and the matrix, the matrix looks almost as hard as the fossil. Tapping with a hammer would just break both along a different fracture line. :sad:
     

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  12. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    If you really want to saw it, a Longitudinal section would show any chambers, if they're there.
     

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  13. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Good, in that I though the back side suggested that the fossil was too similar to the surrounding rock to break out cleanly but was not sure if the hardneses would be different enough since the exposed part is so peculiar (the circle part looks kind of quartz like to my ignorant eyes). I wonder if water was responsible for the ring and surrounding hole.
     
  14. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    Chert=Flint=Silicate=Quartz :notworth:

    The inclusion/fossil is harder than the matrix, but the matrix still looks hard. There may be softer matrix on one end or in the middle, there may be a better contact between the two on one end. Water pushing the rock down the river rounded it, and is responsible for the ring and surrounding hole.
     
  15. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    ahh, I feel better about that now, my rock knowledge is very limited but we saw a lot of quartz where I grew up so I usually can identify it (or think I can) from other "stones" (being clear to semi-opaque helps a lot :grin:) except I thought flint was grey, iron baring rock :oops:

    Ah, it is flint used WITH iron pyrite that I am confusing (I grew up in an area originally populated with native American Indians so trying to start a leaf fire with rocks was a childhood pasttime - never had the right rocks though - fortunately)

    Terri, is there another thing in the rock at the lower left side (on the broken off section)? Blowing up Kevins enlargement suggest not but just checking.
     
  16. Terri

    Terri Sepia elegans Registered

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    Here's a helpfull website..http://geology.com/rocks/chert.shtml

    I don't know how in the heck you spotted that D, there is what looks like a tiny little gastropod (at least I think that's what it is) cross section. I'll check pics. and see if I have one that shows it. :smile:
     
  17. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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  18. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    I have to stop rabbit trailing! Both rock sites have easy to read (ie laymen speak) information that brings back elementary school studies. I was surprised to find obsidian unrelated.

    I don't think I saw the little fossil you are talking about (but think I found it :oops:). My curiosity was releated to where the orange shows up inside the depression on the left where I think you are referring to a "bump" above that.

    Terri, have you put water on the rock to examine it? I assume the cert would show higher reflection than the limestone. Your picture of the broken section also shows what appears to be cert in the upper right in two places, one is oval shaped but neither seem to the concentric circle/oval detail of the original fossil so they may just be deposits rather than preservation.

    I think you are trouble when I do get to make my trip. I will likey want to sit and look at every piece of rock in one place since "spotting" likely candidates is not a technique I will likely ever acquire :grin:
     
  19. Terri

    Terri Sepia elegans Registered

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    On the right this time!

    In that case we'll just plop you down on a big slab of Lebanon Limestone, there's no way you could NOT spot the fossils.
     

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  20. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    That looks like botryoidal texture... Perhaps the whole rock is a chert nodule... This form of silica recrystallization is what would cause beekite rings if it were confined inside the mold of a fossil. 8-)
     

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