BobWill Posted March 20, 2023 Share Posted March 20, 2023 (edited) I found this cephalopod at the Lost Creek spillway site neat Jacksboro Texas. It's from the Finis Shale, Graham Formation, Upper Pennsylvanian. The largest dimension is 16 mm. It seems to be a replacement fossil so no sutures are showing and I don't know of any similar goniatites so that suggests a coiling nautiloid. The only thing I know of with a trapezoidal whorl cross-section like this is a Titanooceras and T. ponderosum has been found there but of course they are huge so it would have to be close to the protoconch. There is an off-center ridge going along the venter and the shell thickens greatly at the ventrolateral margins. I can check for any other features that might help with an ID. edit: It occurred to me that this may not be a cephalopod at all but a gastropod, Amphiscapha subrugosa but I haven't seen one with the ventral ridge. Ventral view Dorsal View Edited March 20, 2023 by BobWill 2 Link to comment Share on other sites More sharing options...
BobWill Posted March 20, 2023 Author Share Posted March 20, 2023 Okay, yeah, looking through my samples of Amphiscapha (Straparollus) I see that's what I have. Never mind 1 Link to comment Share on other sites More sharing options...
BobWill Posted March 20, 2023 Author Share Posted March 20, 2023 Link to comment Share on other sites More sharing options...
cngodles Posted March 21, 2023 Share Posted March 21, 2023 Oh yeah, an Amphiscapha. Fossils of Parks Township - Research | Catalog | How-to Make High-Contrast Photos Link to comment Share on other sites More sharing options...
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