FossilDAWG Posted January 8, 2021 Share Posted January 8, 2021 No, it's all nautilod. Don Link to comment Share on other sites More sharing options...
ClearLake Posted January 8, 2021 Share Posted January 8, 2021 What is being suggested is that it is a cross section like in the middle of the diagram below. Bigger cross sections on each end and progressively smaller towards the middle. Your specimen is only two or maybe a partial third revolution. 3 Link to comment Share on other sites More sharing options...
FossilDAWG Posted January 8, 2021 Share Posted January 8, 2021 Imagine a coiled nautiloid split along the red line as in the image. The yellow lines show where the coils correspond to the fossil in the photo. Don 4 Link to comment Share on other sites More sharing options...
PaleoOrdo Posted January 9, 2021 Author Share Posted January 9, 2021 Thank you very much Clearlake and Don for your excellent explanation! This also explain why the upper 3rd part is a little bigger than the lowest 1st part. Link to comment Share on other sites More sharing options...
PaleoOrdo Posted April 20, 2021 Author Share Posted April 20, 2021 I think it is the species when comparing the pictures from Trygve Strand's article on upper ordovician nautiloids in Oslo region NGT_14_1_2_001-117.pdf (geologi.no) see Pl. II, fig. 6a,b (same shape) and fig. 7 is seen position of siphuncle in same place as in my speciemen near ventral margin. Link to comment Share on other sites More sharing options...
PaleoOrdo Posted April 20, 2021 Author Share Posted April 20, 2021 The name of the species, if I am right, is Discoceras roemeri. A few kilometers away from this, I found another similar species, (at first I thought it was two gastropods) which I think maybe is Discoceras saemanni, or a quite similar species, fig. 1a,b above. I apologize for not have a measure (can compare with the plant-leave which is about 7-9 cm long?) and a better picture, as it was raining that day and the stone too big to bring home. Age is late Katian, 445-447 Ma. 1 1 Link to comment Share on other sites More sharing options...
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