Darbi Posted July 10, 2020 Share Posted July 10, 2020 How do you distinguish between tentaculites and orthoconic cephalopod fossils? Link to comment Share on other sites More sharing options...
Fossildude19 Posted July 10, 2020 Share Posted July 10, 2020 Tentaculites only range in size from 5 mm to 20 mm or so. Orthocones can be as long as 17 feet or as small as about an inch. Tentaculites usually have uneven spacing in their ribbing, where as orthocones are pretty symmetrical and evenly spaced. Tentaculites: From HERE From HERE: 8 Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 IPFOTM -- MAY - 2024 _________________________________________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
Darbi Posted July 15, 2020 Author Share Posted July 15, 2020 @Fossildude19, thank you! I suspected that the ribbing had to do with differentiating between both. I searched for topics on here on Tentaculites before I asked that question and there were several members being confused with a large tentaculite for a small orthocone. For large Tentaculites that are tricky and easily mistaken for small orthocones to the untrained eyes, what's the best ways to identify them correctly? Link to comment Share on other sites More sharing options...
Fossildude19 Posted July 15, 2020 Share Posted July 15, 2020 Well, it helps to know what is found at certain sites. Some sites don't have records of orthocone cephalopods. So that leaves Tentaculites. Generally though, I find that Tentaculites seem to be much thinner than orthocones. Other than that, I've got nothing. 1 Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 IPFOTM -- MAY - 2024 _________________________________________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted July 15, 2020 Share Posted July 15, 2020 Also, of course, tentaculites are pretty much hollow, without any internal structures to speak of, whilst straight shelled cephalopods have septa and a siphuncle. 3 Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
TqB Posted July 15, 2020 Share Posted July 15, 2020 1 minute ago, Tidgy's Dad said: Also, of course, tentaculites are pretty much hollow, without any internal structures to speak of, whilst straight shelled cephalopods have septa and a siphuncle. Although tentaculitids do have septa in the juvenile part of the shell... Hard to find a good image though and I think they're very small at that stage. This is x50 on the original page - roughly 10 cm tall image, so specimen about 2mm long. 4 Tarquin Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted July 15, 2020 Share Posted July 15, 2020 1 hour ago, TqB said: Although tentaculitids do have septa in the juvenile part of the shell... Hard to find a good image though and I think they're very small at that stage. This is x50 on the original page - roughly 10 cm tall image, so specimen about 2mm long. Indeed. Good info but I've never seen this personally. Tis why I said 'pretty much hollow', I should have explained further. Thanks. 3 Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
TqB Posted July 15, 2020 Share Posted July 15, 2020 Just now, Tidgy's Dad said: Indeed. Good info but I've never seen this personally. Tis why I said 'pretty much hollow', I should have explained further. Thanks. You were accurate. I'm just being pedantic - I've never seen it either. 3 Tarquin Link to comment Share on other sites More sharing options...
Fossildude19 Posted July 15, 2020 Share Posted July 15, 2020 @Tidgy's Dad @TqB Good information, gents! Thanks for that. Cheers! 3 Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 IPFOTM -- MAY - 2024 _________________________________________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
Darbi Posted July 20, 2020 Author Share Posted July 20, 2020 @Fossildude19, @Tidgy's Dad, @TqB, that was informative. Thank you! 1 Link to comment Share on other sites More sharing options...
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