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Ordovician in Tennessee (Help!)

Terri

Sepia elegans
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Thanks Kevin! Doesn't really clear much up does it?:hmm: I would think this would be a much more studied topic for anyone interested in ancient cephalopods...even if what I've found are not anything near tentacular markings, I'm now very curious to know more! Most that I have read claims to be "not conclusively related to cephalopods.":roll:

I have more pictures to go through, and when the rain stops I'll go back out and have a better look. Snow last weekend and 70 today with "spring like" storms moving in.:sad:
 

Architeuthoceras

Architeuthis
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Not conclusively related to cephalopods, but still...


Looks like it is possible, unless another trace maker has been identified over the years.

I hope you enjoy getting out for a look. :smile:

22" last week, another 6" yesterday, a high near 18 today, I'm not getting out til spring. :sad:
 

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I suspect that delicate trace fossils produced as surface impressions are going to be difficult to find on weathered surfaces (perhaps showing dissolution features if limestones). You are much more likely to see weathered burrow-fills on such surfaces. I would be looking on freshly split bedding planes for subtle surface traces.

The traces claimed in the past as cephalopod-related now seem to be interpreted as arthropod tracks (typically trilobite) from Kevin’s scanned list.

Landing marks of dead cephalopods are known from the Jurassic platy limestones of Germany though – Seilacher calls them Mortichnia.
 

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Terri

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Thanks Kevin and Hajar, you have sent me off on a reading tanget.

I would be looking on freshly split bedding planes for subtle surface traces.
Would the fact that this little area was briefly quarried, necessarily make it a split bedding plane, or would it had to have been quarried down to a point between formations? :confused: How long would it be before a freshly exposed bedding plane (limestone) before you would call it "weathered"?

Thanks to you both for your patience...:smile:
 

Architeuthoceras

Architeuthis
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Hajar, I got Seilacher's book for christmas, a whole new world of words and fossils to explore. :smile:

Terri, your quarried limestone will need a few more decades to be considered weathered. The dissolution may have occurred between bedding planes prior to being quarried or even lithified. Stromatoporoids, corals, feeding traces or burrows replaced with a more soluble form of limestone may have provided a path.
 

Terri

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I read preview pages of Seilachers' book (google books) today, Trace Fossil Analysis, well actually I read and re-read.:roll: It's all becoming a little more clear now....:smile:
 
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The lovely thing about that book (and all of his other publications) is the huge number of finely-constructed drawings.

I didn't find any trace fossils attributed to cephalopods in there, but Plate 74 shows Chondrites inside a Jurassic ammonite-fill from Poland with the probing branches orientated towards the apex of the phragmocone. Plate 73 shows that the crustacean maker of Thalassinoides in the Jurassic Posidonia Shales of Germany systematically searched for buried ammonite shells and excavated their body chambers (after the aragonitic shell had been demineralized).

Something to look out for in your Ordovician cephalopods?
 

Architeuthoceras

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Burrows on the internal mold of the body chamber of an Ordovician coiled nautiloid from Utah. Obviously not made by the nautiloid, but by something that got in between the mud infill and the shell while it was still there. When the shell dissolved is a good question, but it would have hidden the trace fossils if it was still there... A good thing, or not? :smile:
 

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Interesting! What kind of burrows do you think we're seeing here? The larger structure running diagonally from upper left to bottom right in the middle image looks like a burrow, but what about the other markings?
 

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