BLT Posted October 7, 2018 Share Posted October 7, 2018 I found this rock in a creek in middle Tennessee. (Mississippian, St. Louis Limestone & Warsaw Limestone) It has several fossil imprints and I’m wondering if the circled one is a cephalopod. If not, can anyone tell me what is it? Link to comment Share on other sites More sharing options...
BLT Posted October 7, 2018 Author Share Posted October 7, 2018 Link to comment Share on other sites More sharing options...
BobWill Posted October 7, 2018 Share Posted October 7, 2018 Nice chunk of matrix with a lot of things in it. If that's the back side in the last photo it looks like some bryozoans and broken bits of shell. I can't think of anything else the internal cast could be but cephalopod with an orthoconic shell but to say which one you would probably need to compare it with what typically comes out of that formation. It could be a nautiloid or a bactrites and those lines might be chamber attachments. If so that could be the beginning of a body chamber where they seem to end. Do you find similar cephalopods from the site? 1 Link to comment Share on other sites More sharing options...
minnbuckeye Posted October 7, 2018 Share Posted October 7, 2018 Your thoughts and mine are the same. In this picture, does this show the "flat" end of the cephalopod? If so, is that a hint of a circle in the darker lower edge. If so it may be a siphuncle which substantiates your thoughts of it being a cephalopod. 36 minutes ago, BLT said: I found this rock in a creek in middle Tennessee. (Mississippian, St. Louis Limestone & Warsaw Limestone) It has several fossil imprints and I’m wondering if the circled one is a cephalopod. If not, can anyone tell me what is it? 1 Link to comment Share on other sites More sharing options...
The Amateur Paleontologist Posted October 7, 2018 Share Posted October 7, 2018 Neat fossil you've got there +1 on orthoconic nautiloid cephalopod (at least what's circled in red ) -Christian 1 Opalised fossils are the best: a wonderful mix between paleontology and mineralogy! Q. Where do dinosaurs study? A. At Khaan Academy!... My ResearchGate profile Link to comment Share on other sites More sharing options...
Innocentx Posted October 7, 2018 Share Posted October 7, 2018 Although I can't think what else this would be besides cephalopod, I'm wondering why this line at top (and perhaps this entire side) seem to curve away from completing the expected circle that would make it so. Damage?? 2 "Journey through a universe ablaze with changes" Phil Ochs Link to comment Share on other sites More sharing options...
Kane Posted October 7, 2018 Share Posted October 7, 2018 Something about the banding/ribbing makes me a bit reluctant to go with the nautiloid consensus, as opposed to brachiopod fragment showing plications. A clearer picture under possibly better lighting conditions might better confirm this. 2 ...How to Philosophize with a Hammer Link to comment Share on other sites More sharing options...
Fossildude19 Posted October 7, 2018 Share Posted October 7, 2018 I also think it is not a cephalopod, but looks more like a bivalve/pelecypod. The growth lines are quite close together. 2 Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
BLT Posted October 7, 2018 Author Share Posted October 7, 2018 48 minutes ago, BobWill said: Nice chunk of matrix with a lot of things in it. If that's the back side in the last photo it looks like some bryozoans and broken bits of shell. I can't think of anything else the internal cast could be but cephalopod with an orthoconic shell but to say which one you would probably need to compare it with what typically comes out of that formation. It could be a nautiloid or a bactrites and those lines might be chamber attachments. If so that could be the beginning of a body chamber where they seem to end. Do you find similar cephalopods from the site? Thanks! Yes, that is the back side in the last photo. I am attaching a few more pictures. I have not found any other cephalopods here which I thought looked quite like this one. 57 minutes ago, minnbuckeye said: Your thoughts and mine are the same. In this picture, does this show the "flat" end of the cephalopod? If so, is that a hint of a circle in the darker lower edge. If so it may be a siphuncle which substantiates your thoughts of it being a cephalopod. Thanks! Is this the area you are referring to here? Link to comment Share on other sites More sharing options...
BLT Posted October 7, 2018 Author Share Posted October 7, 2018 48 minutes ago, The Amateur Paleontologist said: Neat fossil you've got there +1 on orthoconic nautiloid cephalopod (at least what's circled in red ) -Christian Thanks! 27 minutes ago, Innocentx said: Although I can't think what else this would be besides cephalopod, I'm wondering why this line at top (and perhaps this entire side) seem to curve away from completing the expected circle that would make it so. Damage?? I’m not sure. I have tried taking closer photos. Link to comment Share on other sites More sharing options...
Kane Posted October 7, 2018 Share Posted October 7, 2018 I'm leaning more toward bivalve/pelecypod with Tim on this one. It seems more flat in these new images. I would expect a nautiloid in this kind of matrix to be a bit more rotund, and the ribbing to be a bit more widely-spaced. 3 ...How to Philosophize with a Hammer Link to comment Share on other sites More sharing options...
BLT Posted October 7, 2018 Author Share Posted October 7, 2018 12 minutes ago, Fossildude19 said: I also think it is not a cephalopod, but looks more like a bivalve/pelecypod. The growth lines are quite close together. Thank you! 3 minutes ago, Kane said: I'm leaning more toward bivalve/pelecypod with Tim on this one. It seems more flat in these new images. I would expect a nautiloid in this kind of matrix to be a bit more rotund, and the ribbing to be a bit more widely-spaced. Gotcha. Thanks! Link to comment Share on other sites More sharing options...
minnbuckeye Posted October 7, 2018 Share Posted October 7, 2018 On the new pictures, I do not see the possible siphuncle that existed in the earlier picture. I just don't see this as brachiopod though. doesn't seem right. how about rugosa coral as a long shot possibility?? 1 Link to comment Share on other sites More sharing options...
BobWill Posted October 7, 2018 Share Posted October 7, 2018 5 hours ago, Kane said: I would expect a nautiloid in this kind of matrix to be a bit more rotund, and the ribbing to be a bit more widely-spaced. Yes, the high cameral ratio does not fit most nautiloids . That's why I included bactrites as a possibility since some like Gymnobactrites sp. have a very high ratio, upwards of 8. However, the more I look and the more new views we get of this, the more mysterious it gets. There is either a lot of preservation distortion or this creature needs it's own new phylum. LOL 2 Link to comment Share on other sites More sharing options...
BLT Posted October 7, 2018 Author Share Posted October 7, 2018 24 minutes ago, minnbuckeye said: On the new pictures, I do not see the possible siphuncle that existed in the earlier picture. I just don't see this as brachiopod though. doesn't seem right. how about rugosa coral as a long shot possibility?? 6 minutes ago, BobWill said: Yes, the high cameral ratios don't fit most nautiloids . That's why I included bactrites as a possibility since some like Gymnobactrites sp. have a very high ratio, upwards of 8. However, the more I look and the more new views we get of this, the more mysterious it gets. There is either a lot of preservation distortion or this creature needs it's own new phylum. LOL Do these pictures help? Link to comment Share on other sites More sharing options...
Monica Posted October 7, 2018 Share Posted October 7, 2018 Is it a possible imprint of where a crinoid stem once resided? Link to comment Share on other sites More sharing options...
Innocentx Posted October 7, 2018 Share Posted October 7, 2018 Here is detail of aviculopectin hinge ribbing, just as example, not as ID. 2 "Journey through a universe ablaze with changes" Phil Ochs Link to comment Share on other sites More sharing options...
BLT Posted October 7, 2018 Author Share Posted October 7, 2018 26 minutes ago, Monica said: Is it a possible imprint of where a crinoid stem once resided? I have wondered the same thing. 11 minutes ago, Innocentx said: Here is detail of aviculopectin hinge ribbing, just as example, not as ID. Mine does have a similar pattern/ribbing. More pics from other angles: Link to comment Share on other sites More sharing options...
DPS Ammonite Posted October 7, 2018 Share Posted October 7, 2018 1 hour ago, BLT said: Do these pictures help? If the zig zag structure in the top photo is a side view of the bottom of the large shell like fossil in the center of the bottom photo then I suspect that it is a brachiopod or pecten with plications. 1 My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
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