Some guy Posted January 5, 2017 Share Posted January 5, 2017 Found this fossil in a creek in middle Tennessee. I originally thought it was a crinoid column, until user ynot pointed out that it was more than likely an orthocone shell. Judging from where it was found, it seems to be from the Ordovician. So now my question is: what species of orthocone do you think it is? Note the size (5 1/2" long, 2" wide) and the segmented pattern. Thanks for the help! Link to comment Share on other sites More sharing options...
ynot Posted January 5, 2017 Share Posted January 5, 2017 Orthocone cephalopod. Tony 1 Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
Some guy Posted January 5, 2017 Author Share Posted January 5, 2017 My god, I think you're right. Any idea as to what its species may be? Link to comment Share on other sites More sharing options...
ynot Posted January 5, 2017 Share Posted January 5, 2017 Sorry, but My knowledge does not go that far. Others will chime in with that information. Tony Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
Some guy Posted January 5, 2017 Author Share Posted January 5, 2017 Alright. Thanks a ton for the help! Link to comment Share on other sites More sharing options...
Fossildude19 Posted January 5, 2017 Share Posted January 5, 2017 Welcome to the Forum. Knowing what county it was found in could help with pinning down a time frame - orthocone cephalopods were very diverse through time. That said, your cephalopod may be too worn to make a definitive ID possible. Regards, EDIT: Here is a geologic map of Tennessee. 1 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...
Fossildude19 Posted January 5, 2017 Share Posted January 5, 2017 If it was found in central Tennessee, it could be Ordovician in age. That could point to something like Actinoceras sp. or Endoceras sp. Regards, 1 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...
Some guy Posted January 5, 2017 Author Share Posted January 5, 2017 Thanks for the warm welcome and the map! The fossil was was found in Rutherford County, which means it was from the Ordovician. And frankly, knowing that I may be holding a genuine Ordovician orthocone fossil makes the 7-year-old Nigel Marvin watcher inside me giggle uncontrollably. Link to comment Share on other sites More sharing options...
DevonianDigger Posted January 5, 2017 Share Posted January 5, 2017 I agree with Tim, looks like Actinoceras sp., but it's too worn to know for sure I think. Very nice either way! Welcome to TFF! Jay A. Wollin Lead Fossil Educator - Penn Dixie Fossil Park and Nature Reserve Hamburg, New York, USA Link to comment Share on other sites More sharing options...
FossilDAWG Posted January 5, 2017 Share Posted January 5, 2017 Can we see the other side? Judging from the end views the "bottom" might show the siphuncle in longitudinal section, which would be more useful than the view already posted that shows only the septa. Don 1 Link to comment Share on other sites More sharing options...
Some guy Posted January 5, 2017 Author Share Posted January 5, 2017 Here's the underside: Link to comment Share on other sites More sharing options...
FossilDAWG Posted January 5, 2017 Share Posted January 5, 2017 Thanks. I am fairly confident in saying this is an endocerid such as Endoceras though there are other genera in the group. I say this because of the large straight-sided siphuncle without secondary deposits, the shallow camerae, and the relatively large size of the specimen. It is definitely not an actinocerid, as those nautiloids have large siphuncles that expand in ring-like structures into the space in each cameral chamber (so the siphuncle looks like a series of rings stuck together), they are almost filled with secondary deposits, and they contact the exterior shell on one side (the ventral) where the ring-like segments are conspicuously flattened. In actinocerids, the siphuncle was a large heavy structure that weighted the shell down so the ventral side lay flat on the sea floor. It is also not a michelinocerid as those nautiloids had relatively small centrally located nummuloid (bead-like) siphuncles. We can exclude oncocerids because the shell is not conspicuously curved, and the oncocerids had small bead-like siphuncles that ran along the outside of the curve. The straight parallel sides exclude genera such as Gomphoceras and Westonoceras. Don 2 Link to comment Share on other sites More sharing options...
Fossildude19 Posted January 5, 2017 Share Posted January 5, 2017 23 minutes ago, FossilDAWG said: Thanks. I am fairly confident in saying this is an endocerid such as Endoceras though there are other genera in the group. I say this because of the large straight-sided siphuncle without secondary deposits, the shallow camerae, and the relatively large size of the specimen. It is definitely not an actinocerid, as those nautiloids have large siphuncles that expand in ring-like structures into the space in each cameral chamber (so the siphuncle looks like a series of rings stuck together), they are almost filled with secondary deposits, and they contact the exterior shell on one side (the ventral) where the ring-like segments are conspicuously flattened. In actinocerids, the siphuncle was a large heavy structure that weighted the shell down so the ventral side lay flat on the sea floor. It is also not a michelinocerid as those nautiloids had relatively small centrally located nummuloid (bead-like) siphuncles. We can exclude oncocerids because the shell is not conspicuously curved, and the oncocerids had small bead-like siphuncles that ran along the outside of the curve. The straight parallel sides exclude genera such as Gomphoceras and Westonoceras. Don Great information, Don. Thanks for chiming in on this thread. I always learn something when you post. Regards, 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...
Some guy Posted January 5, 2017 Author Share Posted January 5, 2017 34 minutes ago, FossilDAWG said: Thanks. I am fairly confident in saying this is an endocerid such as Endoceras though there are other genera in the group. I say this because of the large straight-sided siphuncle without secondary deposits, the shallow camerae, and the relatively large size of the specimen. It is definitely not an actinocerid, as those nautiloids have large siphuncles that expand in ring-like structures into the space in each cameral chamber (so the siphuncle looks like a series of rings stuck together), they are almost filled with secondary deposits, and they contact the exterior shell on one side (the ventral) where the ring-like segments are conspicuously flattened. In actinocerids, the siphuncle was a large heavy structure that weighted the shell down so the ventral side lay flat on the sea floor. It is also not a michelinocerid as those nautiloids had relatively small centrally located nummuloid (bead-like) siphuncles. We can exclude oncocerids because the shell is not conspicuously curved, and the oncocerids had small bead-like siphuncles that ran along the outside of the curve. The straight parallel sides exclude genera such as Gomphoceras and Westonoceras. Don Wow. Very good information there Don. I think you've found the creature we needed. I guess that's it, then. Thanks so much for the help, everyone! Link to comment Share on other sites More sharing options...
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