aek Posted November 7, 2022 Share Posted November 7, 2022 (edited) I found some time this past weekend while passing through to take a look at a small stream cut exposing cyclothem layers of marine limestone and swamp coal in east central Illinois. Here are some fossils I found from the marine rocks. Bond formation. Offshore sediments, deep water. Ditomopyge sp. UV Lophophyllidium Not sure what these are. These are magnified. Each one about the size of a grain of sand. Assuming they are crinoidal. Any help with ID appreciated. Very tiny tooth measures <.5mm. The acrodin cap is characteristic of an actinopterygian, but I don't know if it can be identified any further than that. Thanks for looking. Edited November 7, 2022 by aek 10 Link to comment Share on other sites More sharing options...
Phevo Posted November 8, 2022 Share Posted November 8, 2022 (edited) 6 hours ago, aek said: Not sure what these are. These are magnified. Each one about the size of a grain of sand. Assuming they are crinoidal. Any help with ID appreciated. These look like partially silified ambulacral plates from a regular sea urchin to me, but I don't know anything about the bond formation Edited November 8, 2022 by Phevo 3 Link to comment Share on other sites More sharing options...
aek Posted November 8, 2022 Author Share Posted November 8, 2022 @Phevo Indeed, that is an interesting observation. At the moment I can't find any information about echinoderms other than crinoids from this formation, but maybe I can dig a little deeper at school later in the week. I took another look at the residues that remained on my screen and found some spines that probably belong to these plates. They don't appear to be crinoidal or bryozoan so that is intriguing. 3 Link to comment Share on other sites More sharing options...
Missourian Posted November 8, 2022 Share Posted November 8, 2022 It is wonderful to find silicified fossils in limestone. You never know what can turn up in the residue. I've had pretty good luck in a Pennsylvanian limestone in Missouri: Context is critical. Link to comment Share on other sites More sharing options...
aek Posted November 8, 2022 Author Share Posted November 8, 2022 @Missourian beautiful finds! Link to comment Share on other sites More sharing options...
deutscheben Posted November 9, 2022 Share Posted November 9, 2022 Thanks for sharing! Those are similar to Bond Formation finds I’ve had from La Salle County (including urchin spines) but I haven’t encountered any down here in central Illinois yet. 1 Link to comment Share on other sites More sharing options...
aek Posted November 9, 2022 Author Share Posted November 9, 2022 14 hours ago, deutscheben said: Thanks for sharing! Those are similar to Bond Formation finds I’ve had from La Salle County (including urchin spines) but I haven’t encountered any down here in central Illinois yet. Interesting, have you by chance come across any papers with descriptions of urchins from this formation? Link to comment Share on other sites More sharing options...
deutscheben Posted November 9, 2022 Share Posted November 9, 2022 The only formal reference I am familiar with is a 1931 thesis from the University of Illinois: Griffin, Judson Roy. The Fauna of the La Salle Limestone. Urbana, Ill. Unfortunately it is not available electronically, but I have read the print copy and it documents the presence of Archaeocidaris spines and plates from the deposit. Link to comment Share on other sites More sharing options...
aek Posted November 10, 2022 Author Share Posted November 10, 2022 4 hours ago, deutscheben said: The only formal reference I am familiar with is a 1931 thesis from the University of Illinois: Griffin, Judson Roy. The Fauna of the La Salle Limestone. Urbana, Ill. Unfortunately it is not available electronically, but I have read the print copy and it documents the presence of Archaeocidaris spines and plates from the deposit. Thanks for this information. After doing a search, it appears there is only a single copy of this thesis, but that will give me a reason to pop in to the library next time I'm in the Urbana area. There are some nice examples of Archaeocidaris online for reference. Link to comment Share on other sites More sharing options...
Tales From the Shale Posted November 10, 2022 Share Posted November 10, 2022 Love the pygidium! La Salle has members of Amuera that preserve to look very similar. Also did you intentionally seek out those microfossils? Or was that by happenstance? Link to comment Share on other sites More sharing options...
aek Posted November 10, 2022 Author Share Posted November 10, 2022 I was looking for microfossils in specific layers..and trilobites.. however I wasn't expecting to find sea urchin remains, so this was a nice surprise. Link to comment Share on other sites More sharing options...
Tales From the Shale Posted November 11, 2022 Share Posted November 11, 2022 Interesting. I haven't even scratched the micro fossil world. I think I need to reconsider. Link to comment Share on other sites More sharing options...
Petalodus12 Posted November 18, 2022 Share Posted November 18, 2022 Nice actinopt tooth! I'd agree that it can't be identified to anything more specific, as Carboniferous actinopterygian teeth are pretty conserved across taxa Link to comment Share on other sites More sharing options...
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