Terry Dactyll Posted October 19, 2010 Share Posted October 19, 2010 (edited) Ive uncovered what I think is the actual ' texture ' of an ammonite shell preserved in pyrite .... Its a first for me for ammonites although it happend on the keel of a nautilus once... If you look at the 'green ammonite bed' Nautilus that still has all its shell and markings intact then you see the same circumferential striations as on the calcite and pyrite nautilus .... its this preservation that I base my ammonite texture theory on... Take a look and see what you think and I'd be intrested to see if anyone else got any ammonite shell texture preservation to share?... Ammonite shell & Nautilus shell Edited October 19, 2010 by Terry Dactyll Cheers Steve... And Welcome if your a New Member... Link to comment Share on other sites More sharing options...
frozen_turkey Posted October 19, 2010 Share Posted October 19, 2010 Wow thats amazing!!!! Yep thats the origenal texture. It realy rare due to the fact the shell is made of agraget* (you propably already knew that) and it doesnt hang around to presurve. I have incountered primative c-pods over here that have the orginal shell priserved, but not nearly as well presurved as yours. Remember that rare cunk of amminoid that i enter for the FOTM? And do you remeber the prep lines that were next to it? I exposed a small portion of that original shel texter. Nice find!! -Frozen * EDIT: That would be aragonite Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted October 19, 2010 Share Posted October 19, 2010 Holy snot that's awesome! Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
tracer Posted October 19, 2010 Share Posted October 19, 2010 aragonite is a form of CaCO3 that is unstable under normal conditions and therefore usually converts to calcite by the time 10-100 million years have passed. but it is more stable under pressure, so well-buried old fossils can sometimes beat the odds. Link to comment Share on other sites More sharing options...
JohnJ Posted October 19, 2010 Share Posted October 19, 2010 Steve, you always seem to show us something very cool from the ammonite beds you haunt. Thanks. The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
Terry Dactyll Posted October 19, 2010 Author Share Posted October 19, 2010 Cheers guys.... Its an unusual shell to.... I only ever found 1 other previously.... Cheers Steve... And Welcome if your a New Member... Link to comment Share on other sites More sharing options...
nala Posted October 19, 2010 Share Posted October 19, 2010 Hello,Steve ,fantastic specimen ,my best cephalopods shell preservation are mostly Calcite (Plienbachian of Normandy)and pyritised (Albian of Troyes),regards Link to comment Share on other sites More sharing options...
Scylla Posted October 19, 2010 Share Posted October 19, 2010 very cool, but please explain how you know that is an ammonite if the texture matches a nautalus? I'm asking to learn, I know that the segments between chambers on ammonites are more complex, but are there other clues? Link to comment Share on other sites More sharing options...
MikeD Posted October 20, 2010 Share Posted October 20, 2010 (edited) jaw drops to the floor..... Edited October 20, 2010 by MikeD Link to comment Share on other sites More sharing options...
Terry Dactyll Posted October 20, 2010 Author Share Posted October 20, 2010 nala.... Beautiful specimens... the shell on the Lytoceras? is very detailed and thanks for posting them...by the way, did you notice the nautilus for sale on the heritage auction site from France with red mineral infil in some of the chambers... Mike ... Cheers.... Scylla... The overall shape of the Nautilus (Cenoceras) is very different from that of an ammonite as well as the internal chamber walls (sutures) are less complex as you rightly pointed out....These are the distinguishing characteristics that I use to distinguish between the two.... I will post you a couple of examples to compare.... Nautilus with Shell..... Without shell showing internal chamber walls Ammonite with shell.... Without shell revealing complex sutures Cheers Steve... And Welcome if your a New Member... Link to comment Share on other sites More sharing options...
Scylla Posted October 28, 2010 Share Posted October 28, 2010 nala.... Beautiful specimens... the shell on the Lytoceras? is very detailed and thanks for posting them...by the way, did you notice the nautilus for sale on the heritage auction site from France with red mineral infil in some of the chambers... Mike ... Cheers.... Scylla... The overall shape of the Nautilus (Cenoceras) is very different from that of an ammonite as well as the internal chamber walls (sutures) are less complex as you rightly pointed out....These are the distinguishing characteristics that I use to distinguish between the two.... I will post you a couple of examples to compare.... Nautilus with Shell..... Without shell showing internal chamber walls Ammonite with shell.... Without shell revealing complex sutures Thanks, I think I get it, the Nautilus' largest chamber covers over the previous whorls, and the Ammonite shows the previous whorls. But just to make sure could you send me the actual fossils in those pictures, I think I'll understand better with the 3-d viewing Link to comment Share on other sites More sharing options...
Terry Dactyll Posted October 28, 2010 Author Share Posted October 28, 2010 But just to make sure could you send me the actual fossils in those pictures, I think I'll understand better with the 3-d viewing..... In the post Cheers Steve... And Welcome if your a New Member... Link to comment Share on other sites More sharing options...
Ordovician_Odyssey Posted October 29, 2010 Share Posted October 29, 2010 heres one with some nice texture, i got it at the museum of nature. -Shamus The Ordovician enthusiast. Link to comment Share on other sites More sharing options...
Terry Dactyll Posted October 30, 2010 Author Share Posted October 30, 2010 heres one with some nice texture, i got it at the museum of nature. Trilobite Guy..... I see you got a combination of the nacre shell and sutures showing there, very nice aquisition.... Cheers Steve... And Welcome if your a New Member... Link to comment Share on other sites More sharing options...
Plantguy Posted October 30, 2010 Share Posted October 30, 2010 Steve, pretty cool find--cant say that I've seen too many examples like that before. Very nice addition to the collection! I'm fascinated by the complexity of some suture patterns that the ammonites possess and that somehow the simple non-complex natiloid approach has survived to this day. Nala and trilobite guy very nice ammos as well! Regards, Chris Link to comment Share on other sites More sharing options...
Ordovician_Odyssey Posted November 12, 2010 Share Posted November 12, 2010 my ammmo is sliced in half, and exposes crystal that has reformed in the "chambers" of the shell -Shamus The Ordovician enthusiast. Link to comment Share on other sites More sharing options...
Wrangellian Posted November 14, 2010 Share Posted November 14, 2010 Thanks, I think I get it, the Nautilus' largest chamber covers over the previous whorls, and the Ammonite shows the previous whorls. But just to make sure could you send me the actual fossils in those pictures, I think I'll understand better with the 3-d viewing Some ammonites are evolute (all whorls showing) and others are more involute (inner whorls covered), and some of those have smoother shells like the nautiloids. I think the only way to tell if you can't see the sutures is just to familiarize yourself with the different genera. Link to comment Share on other sites More sharing options...
fossiljunkie Posted November 18, 2010 Share Posted November 18, 2010 nice and very cool. congratulations on that one.wow Today's the day! Mel Fisher Link to comment Share on other sites More sharing options...
Terry Dactyll Posted November 19, 2010 Author Share Posted November 19, 2010 Chris.... Well.. The Nautilus survived long before ammonites even evolved as well as survived after they dissapeared... They must be doing something right...maybe its surviving the temperature fluctuations of the sea.... fossiljunkie.... Thanks.... I chucked a new rock on the bench yesterday to start getting a feel for it..... I may grab a coupler hours on it later... Cheers Steve... And Welcome if your a New Member... Link to comment Share on other sites More sharing options...
Foshunter Posted November 19, 2010 Share Posted November 19, 2010 (edited) This is a Eutrephoceras sp. from the creek in Texas that Tera (barefoot girl) hunts, showing a small portion of shell pattern that didn't break away when removed from the sandstone matrix. Next photo is a portion of a chamber that chipped off revealing tiny crystals, they were also at the entrance of the living chamber. --Tom Edited November 19, 2010 by Foshunter Grow Old Kicking And Screaming !!"Don't Tread On Me" Link to comment Share on other sites More sharing options...
Terry Dactyll Posted November 19, 2010 Author Share Posted November 19, 2010 This is a Eutrephoceras sp. from the creek in Texas that Tera (barefoot girl) hunts, showing a small portion of shell pattern that didn't break away when removed from the sandstone matrix. --Tom Tom.... Thats a very nice nautilus.... I know BFG has had some good finds from over there and the quality of preservation is fantastic.... Its great to see the shell texture, thanks for sharing it... Cheers Steve... And Welcome if your a New Member... Link to comment Share on other sites More sharing options...
BobWill Posted November 21, 2010 Share Posted November 21, 2010 Some ammonites are evolute (all whorls showing) and others are more involute (inner whorls covered), and some of those have smoother shells like the nautiloids. I think the only way to tell if you can't see the sutures is just to familiarize yourself with the different genera. Correct and the other tell is the position of the sipuncle. Nautiloid if central, ammonoid if ventral. Link to comment Share on other sites More sharing options...
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