fossilzz Posted October 31, 2019 Share Posted October 31, 2019 I found this orthocone a while back at Arkona (devonian) and I thought it was dolorthoceras, but now I am not so sure. It has a strange mark protruding from centre of each chamber. Any help would be appreciated! d! Link to comment Share on other sites More sharing options...
Al Dente Posted November 1, 2019 Share Posted November 1, 2019 I think that marking is the siphuncle. It could be Bactrites. 2 Link to comment Share on other sites More sharing options...
FossilDAWG Posted November 1, 2019 Share Posted November 1, 2019 I agree with All Dente. Don 2 Link to comment Share on other sites More sharing options...
Shamalama Posted November 1, 2019 Share Posted November 1, 2019 I agree that the line could be the siphuncle. Remember that you are not seeing the full body fossil, just the interior of the shell that was replaced. The siphuncle in some species is towards the edge of the shell rather than in the middle. Did you find it in the Widder fm. or the Arkona fm. ? Looks to me like it's from the Arkona by the pyritic preservation but I could be wrong. Nice that you found such a large piece of a cephalopod regardless which formation it came from. The pieces I find are often fragmentary. 2 -Dave __________________________________________________ Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave. To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrain. - John McPheeIf I'm going to drive safely, I can't do geology. - John McPheeCheck out my Blog for more fossils I've found: http://viewsofthemahantango.blogspot.com/ Link to comment Share on other sites More sharing options...
fossilzz Posted November 1, 2019 Author Share Posted November 1, 2019 Thanks for the input, it could possibly be from the Arkona fm as well. I was wondering if it was bactrites, but the shell angle to me does not look like bactrites. From what I've seen from photos it seems complete bactrites have a much more gradual taper. Link to comment Share on other sites More sharing options...
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