Anyone found a good fossil?

Discussion in 'Cephalopod Fossils' started by Phil, Apr 28, 2003.

  1. Phil

    Phil Colossal Squid Supporter Registered

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  2. Fujisawas Sake

    Fujisawas Sake Larger Pacific Striped Octopus Supporter Registered

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    Sorry... Just a fossil clam given to me by an old friend... :P

    Sushi and Sake,

    John
     
  3. WhiteKiboko

    WhiteKiboko Colossal Squid Supporter Registered

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    all i have as far as fossils are concerned are just bivalve pieces and some augers...not really exciting, dont knowq much about them and theyre not cephs.... :|
     
  4. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    Here is a fossil I found, from the Ordovician (about 450 mya) of Utah. You can see why they call Nautilus a living fossil. This is Plectolites, at least a fossil of the shell. Most of the chambers were broken and got filled with seafloor sediment, the left side is missing altogether. The chambers in the very center were still hollow when the sediment was turned to limestone, and latter the void was filled with calcite crystals, this destroyed the septa. The Siphuncle is a little different than in Nautilus

    A fairly large file (196K) for detail

    :ammonite:
     
  5. Phil

    Phil Colossal Squid Supporter Registered

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    Wow! That's a beauty!

    It's amazing to thing how similar this nautilus is to the modern species. I wonder which group of nautiloids it belonged to? According to my references the order of nautiloid that gave rise to our modern species did not appear until the early Devonian. So if yours is from the even more ancient Ordovician then it must belong to a separate long extinct nautiloid order.

    Yet it is so similar! Amazing. I'll see if I can find out some info on Plectolites.

    Phil
     
  6. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    Fossil Goniatite shells with an orthocerid nautiloid. Mississippian (Early Carboniferous) about 320 mya.
    :ammonite:
     
  7. Phil

    Phil Colossal Squid Supporter Registered

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    That is a fantastic find.......do you find stuff like this regularly? Do you keep the fossils or sell them on?

    Totally jealous!
     
  8. tonmo

    tonmo Titanites Staff Member Webmaster Moderator

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    Yeah, seriously 8) -- how and when did you find that one?
     
  9. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    Hi Guys!
    The Goniatites are all in a single concretion. I found it in a wash after a gully-washer washed it out. It is the only concretion of that age I have found that still shows the nacreous luster of the original great-great-grandmother of pearl. I watch the National Weather Service page all the time and if I see a good storm go over that area, then I go see if any more wash out.
    I usually keep the good ones an leave the others for other collectors. They are found on US Public Land (BLM) so I can only collect them in reasonable quantities, for personal use, and cannot sell or trade.
    :ammonite:
     
  10. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    It's hard to take a picture of the nacre in normal light, so I took a picture of a small piece of broken shell from the same concretion, then took a picture under the microscope with the light just right to show the colors. This is a piece of shell from Goniatites multiliratus, you can see the small ridges (lirae) that gives it it's name.
     
  11. Phil

    Phil Colossal Squid Supporter Registered

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    If anyone is wondering why these ammonoids do reflect the light so beautifully as demonstrated in Kevin's picture above, it is because the shell of the ammonoid was composed of alternating layers of aragonite and conchiolin. The mantle secreted each layer as the creature grew and added chamber following chamber to its shell. Aragonite, composed of vertical prisms reflected light at a different wavelength to the conchiolin below. With four or five layers this means that intact shells of ammonoids often exhibit a rather nice subtle rainbow effect.

    Ammonoids are found in many different colours, but this is an artefact of the type of mineral that precipitated into the gaps in the cells of the creature during the process of fossilisation. So a greenish ammonite does not necessarily mean that was the colour of the creature when it was alive. It seems highly likely that the ammonoid would have employed some form of countershading as a defense, much like the nautilus, though the exact form of which is anyones guess!
     
  12. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    Thanks for that great explanation Phil,

    Here is another picture from the same concretion, I believe this is a shell fragment from an orthocerid nautiloid. I don't know why but it seems the fragments are alot more colorful than the shell on a complete fossil.
    :ammonite:
     
  13. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    Can anyone help me out with this ammonite. It is unlocalised (was just given to us yesterday). I'd love to know what it is (genus maybe, if possible), how old it is and where it has come from (if any of this is possible). It could have come from New Zealand, but it could have come from Mars.

    It is rather distinctive. It's greatest dimension is 24cm (to the end of that pretty bizarre spike). Oooops, Phil has just corrected me - 'spike' = lappet. I should stick to squid and octopus :D

    Cheers
    Steve
     
  14. Clem

    Clem Architeuthis Supporter Registered

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    Steve,

    I found another lappet-bearing ammonite, online. Of course, the image was posted sans identification, but it makes for an interesting comparison with your new fossil. You can see the outline of the bisected lappet in the stone, extending to the edge of the photo.

    Clem

    ps: I had no idea the proper term was "lappet," either.
     
  15. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    Thought I'd post another image of some more stunning ammonites that have 'turned up' on the desk of late.

    Upper left: Phylloceras sp. Albian (Cretaceous), Madagascar.

    Lower left: Lamberticeras sp. Upper Calvian (Jurassic), Russia.

    Lower right: Hoploscaphites nicolletii. Fox Hills formation, South Dakota (Late Cretaceous)

    Upper right: Desmoceras cf. mahabobokensis, Albian (Cretaceous), Madagascar.

    There are some other truly stunning bits and pieces, images of which I'll post another time (they're actually in the display cabinet at home :madsci: ). I really have been spoilt lately.

    Cheers
    O
     
  16. Phil

    Phil Colossal Squid Supporter Registered

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    Looking at this again actually I think that this form of spike on the aperture is called a spine. How original! :oops:

    Lappets were lobes that projected from either side of the aperture, so I was completely wrong. I should stick to watching TV from the seventies!

    Still not having much luck in identifying the specimen, hopefully when I get this CD-Rom on fossil Mollusca soon it may be on there.
     
  17. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    Quoting most of this out of the treatise: A ventral extension of the peristome (apertural margin) may form a ventral lappet; or the ventral extension may be developed as a long, tapering rostrum.
    More common are the paired lateral lappets.
    As for an identification, Mortoniceras of the Early Cretaceous has the same kind of mature modification, but it has strong ribs covering it's shell. Pectinatites from the Late Jurassic also has a rostrum like that but it has ribs also. The fossil looks alot like Oxytropidoceras from the Cretaceous, but I don't know what the mature aperture looks like. Need more input for better I.D., any sutures visible?
    The other fossils are great, do you have I.D.'s and locality info. on them?
     
  18. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    Duh!!!!! :oops:
     
  19. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    Kevin, Phil, Clem, I'll get back to you on this one, but it will be a couple of days away (full swing on something else right now). The shell has many apparent low-profile/gently undulating ribs, but no sutures are apparent. Ta for the input. It's great having a fossil forum!!
    Cheers, O
     
  20. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

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    Here are some pictures of an excavation I did a few years back. You can see a map of the excavation at this link "map"
    The old guy in the picture is me. These are ceratitic ammonoids from the Early Triassic, approx. 240mya, the first picture shows a closeup of one of the sutures.

    Enjoy :ammonite:
     

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