minnbuckeye Posted September 21, 2022 Share Posted September 21, 2022 I had brought home a piece of Galena/ Ordovician matrix that had some unidentifiable critters hidden in the rock. Time was taken to extract what I am sure is a cephalopod from the matrix. Haven hunted this formation for years, I can honestly say this is the first cephalopod found exhibiting its curved features discovered by me. Attempts to ID the fossil have been fruitless, so I am asking for help! The fossil fractured during its prep revealing what I see as a siphuncle. Here is the repaired specimen: 4 Link to comment Share on other sites More sharing options...
FossilDAWG Posted September 21, 2022 Share Posted September 21, 2022 There are a number of oncocerid nautiloids with this sort of very open coil. You might check into Richardsonoceras, Loganoceras, or Manitoulinoceras, for example. Nice find! Don 2 1 Link to comment Share on other sites More sharing options...
connorp Posted September 21, 2022 Share Posted September 21, 2022 Could be Centrocyrtoceras. From Figure 11-11 of "Fossils of the Upper Ordovician Platteville Formation in the Upper Midwest USA: An Overview" (Kolata, 2021). 3 Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted September 21, 2022 Share Posted September 21, 2022 Tremendous find, Mike. I like the suggestion of Centrocyrtoceras, as it twists slowly off the flat plane. 1 Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
RCFossils Posted September 21, 2022 Share Posted September 21, 2022 Nice find! Those loosely coiled ones are hard to find that complete. 1 Link to comment Share on other sites More sharing options...
minnbuckeye Posted September 21, 2022 Author Share Posted September 21, 2022 I had to re-post. Something goofy happened above. @connorp, I like the suggestion!! But I can not find it mentioned in the Galena, only the Platteville locally. Was it present through many formations?? Mike Link to comment Share on other sites More sharing options...
connorp Posted September 21, 2022 Share Posted September 21, 2022 (edited) @minnbuckeye According to John Catalani, there is at least one species present in the Galena. You might email him photos to get his thoughts. "Biostratigraphy of the Middle and Late Ordovician Cephalopods of the Upper Mississippi Valley Area" (Catalani, 1987) Edited September 21, 2022 by connorp Link to comment Share on other sites More sharing options...
minnbuckeye Posted September 22, 2022 Author Share Posted September 22, 2022 @connorp, Funny you should suggest John. I had already forwarded the pictures to him and if it is a unique specimen, offered it up for his collection. apparently he is out on a hunting excursion currently. Will post his response when recieved! Mike Link to comment Share on other sites More sharing options...
minnbuckeye Posted September 27, 2022 Author Share Posted September 27, 2022 @connorp, John had a chance to look at the pictures. Here is his response. I believe that specimen is a gastropod. They have been variously named Ecculiomphalus and, more recently, Asgardaspira. The most interesting thing about these guys is that they were septate. Asgardaspira evolvens (Koken, 1897), CNIGRM 5756 (80/10903), internal mould; A, detail of umbilical wall showing muscle attachment scar (m1); B, oblique basal view showing spiral trace on outer whorl surface and muscle attachment scar m2; C, detail of muscle attachment scar m2; D, upper surface showing broad dorsal ridge; E, detail of circumbilical ridge and groove complex; F, standard orientation of dextral hyperstrophic shell, showing location of muscle attachment scar m1 and the dorsal angulation (da); G, basal surface; H, oblique umbilical view showing circumbilical ridge and groove complex and muscle attachment scar m1 (arrow). Scale bars: 2 mm (A, C); 4 mm (B); 10 mm (D-H). 4 Link to comment Share on other sites More sharing options...
FossilDAWG Posted September 27, 2022 Share Posted September 27, 2022 I was actually not aware of these septate gastropods. Don Link to comment Share on other sites More sharing options...
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