BobWill Posted August 22 Share Posted August 22 These came from the Silica Shale Formation near Sylvania Ohio, Middle Devonian. They seem far too small for the orthoconic cephalopods they resemble and I can see no evidence of septa or siphuncles on the ends. The scale is millimeters. This is the best image I can provide. The ratio of diameter to segment spacing ranges from 3:1 to 5.33:1. Link to post Share on other sites
BobWill Posted August 22 Author Share Posted August 22 @Herb these are from the matrix you sent. Link to post Share on other sites
Tidgy's Dad Posted August 22 Share Posted August 22 I think at least some of those are likely to be Tentaculites bellulus. 1 4 Link to post Share on other sites
BobWill Posted August 22 Author Share Posted August 22 15 minutes ago, Tidgy's Dad said: I think at least some of those are likely to be Tentaculites bellulus. Thanks. I hadn't thought they could be that small but I suppose broken pieces could be. Link to post Share on other sites
TqB Posted August 22 Share Posted August 22 I'd suspect tentaculitids too. 1 1 1 Link to post Share on other sites
Rockwood Posted August 22 Share Posted August 22 Could there be Cornulites in the mix too ? Link to post Share on other sites
Fossildude19 Posted August 22 Share Posted August 22 They look like Tentaculites to me. 1 1 Link to post Share on other sites
minnbuckeye Posted August 22 Share Posted August 22 How does one differentiate Tentaculites from Cornulites other than Cornulites are often attached to another fossil???? This has always been a question in the back of my mind and is good for @BobWill to understand. Link to post Share on other sites
Tidgy's Dad Posted August 22 Share Posted August 22 (edited) 11 hours ago, BobWill said: Thanks. I hadn't thought they could be that small but I suppose broken pieces could be. They are often microfossils in the Silica Shale, here's an image, the ones without striations are Styliolites cf. fissurella, another tentaculitid. Tentaculida' Edited August 22 by Tidgy's Dad 1 3 Link to post Share on other sites
Tidgy's Dad Posted August 22 Share Posted August 22 (edited) 2 hours ago, minnbuckeye said: How does one differentiate Tentaculites from Cornulites other than Cornulites are often attached to another fossil???? This has always been a question in the back of my mind and is good for @BobWill to understand. It's a question of shell microstructure, but, loosely speaking, tentaculitids may have a slight curve in the microconch but are otherwise uniform in growth in each species. Most are straight, but some have a slight curve or bend at the apex which will be fairly consistent within a species. Cornulitids grow more irregularly and exhibit more seemingly random bends, curves and growth lines. Microconchids are mostly coiled. Usually, it's wise to try to establish which species are found in a formation and work from there. Edited August 22 by Tidgy's Dad 3 1 1 Link to post Share on other sites
Herb Posted August 25 Share Posted August 25 There are both Tentaculites and Cornulites in the Silica Shale 1 Link to post Share on other sites
MaryXmas Posted September 24 Share Posted September 24 Those look to be Orthoconic nautiloid if cross referencing it with the Silica Formation book. Link to post Share on other sites
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