Wrangellian Posted November 21, 2018 Share Posted November 21, 2018 I've received a couple nice Upper Ordovician additions to my collection courtesy of @JUAN EMMANUEL and I'm finally posting them now... (Thanks Juan!) First, is this Tentaculites or Cornulites? I wish I could get better pics. Manitoulin Fm, Hamilton, ON. Link to comment Share on other sites More sharing options...
Wrangellian Posted November 21, 2018 Author Share Posted November 21, 2018 Second: We have the ID for this orthocone, Treptoceras sp., Georgian Bay Fm of Toronto. I'd like to know to to what extent we are seeing external ornamentation and what extent is exposed internal features (eg. septa from a partially crushed/collapsed shell), and what are those 'knobs' on the smaller specimen and toward the narrow end of the larger? Anyone have any ideas? Reverse side with snails and apparently large ichno trails: Link to comment Share on other sites More sharing options...
Rockwood Posted November 21, 2018 Share Posted November 21, 2018 I think the profile is more consistent with Tentaculites on the first one. I think the knobby look is external, and the smooth internal/intermediate for the cone. Link to comment Share on other sites More sharing options...
Rockwood Posted November 21, 2018 Share Posted November 21, 2018 After a little study I may have to reverse direction on the first one. They do have the look of a shaving from a metal lathe. That would be cornulites. 2 Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted November 21, 2018 Share Posted November 21, 2018 Cornulites. The internal structure of Treptoceras looks like this : (from "Cincinnatian Fossils and Stratigraphy." What you have there is an internal mold of the outer shell showing the chambers. And the bumps at the base do show on well preserved specimens, it's some sort of ornamentation. Robert C. Frey "Journal of Palaeontology". Vol.63, No. 5, (Sep., 1989), pp.604-620. 2 Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
minnbuckeye Posted November 21, 2018 Share Posted November 21, 2018 Could the knobs be encrusted bryozoans?? From the Drydredgers: Many Cephalopods were encrusted with the bryozoan, Spatiopora, which shows aligned monticules.This suggests the Cephalopods' shells were encrusted with these bryozoans while they were swimming. Link to comment Share on other sites More sharing options...
Northern Sharks Posted November 21, 2018 Share Posted November 21, 2018 As far as I'm aware, we only have Devonian Tentaculites here in Ontario. In my opinion, those are Cornulites. I can't speak for the GB formation, but they were a rare find from the Verulam. I only ever found 2 over all the years I collected that particular formation. There's no limit to what you can accomplish when you're supposed to be doing something else Link to comment Share on other sites More sharing options...
Wrangellian Posted November 22, 2018 Author Share Posted November 22, 2018 Thanks everyone for the info and ideas. My pics aren't good enough to show it but on close examination I'm sure I'm looking at shell material on the Treptoceras. (I don't see any bryozoan encrustation.) It looks as if the knobs kind of turn into ribs toward the mature end of the shell, though some of them may have been abraded off (either before deposition or after erosion). The thick shell is evident especially at the open end of the smaller specimen. If I didn't think it would be a waste of time I'd try to get more pics. I see by Sepkoski that Tentaculitids extend from the Ordovician to the Devonian, and Tentaculites is the only genus in the Ordo (from the Tremadocian on up thru the Devonian). But I'll take y'all's word for it that this is Cornulites, and I'm happy about that! (Aside: Sepkoski lists Tentaculitids within the Molluca, while the Cornulitids are under 'Problematica'. To me they look close enough that they should be in the same group, whatever that might be, or is this a case of convergent evolution?) Link to comment Share on other sites More sharing options...
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