Lone Hunter Posted December 18, 2023 Share Posted December 18, 2023 Cretateous oyster from Grayson formation that I need to mark off my list. Largest oyster I've found, both valves present, weighs half a pound, but umbo and beak are obliterated so undecided. I think Ostrea when I see ruffles. And now Gryphaea are going by Pycnodonte? They stick an e on the end of fish name and it's an oyster now? Why do they want to confuse us more 1 Link to comment Share on other sites More sharing options...
DPS Ammonite Posted December 18, 2023 Share Posted December 18, 2023 (edited) Might be an Exogyra. 3 possible species from Mainstreet and Grayson: Exogyra clarki; Exogyra drakei; or Exogyra cartledgei. ID of Texas oysters tough since there are a wide variety of shapes for a single species. E. Böse, "On a New Exogyra from the Del Rio Clay and Some Observations on the Evolution of Exogyra in the Texas Cretaceous," Bulletin No. 1902 of the University of Texas Bureau of Economic Geology, (1919). https://repositories.lib.utexas.edu/server/api/core/bitstreams/b7186570-2c68-4f71-b121-24c8ff20c762/content Stanton, 1947. Studies of some Comanche pelecypods and gastropods. USGS Professional Paper 211 See plates 22-23. https://pubs.usgs.gov/pp/0211/report.pdf Edited December 18, 2023 by DPS Ammonite 3 1 My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
M Harvey Posted December 18, 2023 Share Posted December 18, 2023 I would agree with Exogyra. 1 Link to comment Share on other sites More sharing options...
Plax Posted December 18, 2023 Share Posted December 18, 2023 is it bioimmured with an ammonite? Link to comment Share on other sites More sharing options...
Lone Hunter Posted December 18, 2023 Author Share Posted December 18, 2023 (edited) 8 hours ago, Plax said: is it bioimmured with an ammonite? Learning new word here, not sure what your seeing and how to interpret. Edit, gotcha, I assume it's an ammonite now that you mentioned it, so they both grew together? Edited December 18, 2023 by Lone Hunter Link to comment Share on other sites More sharing options...
hemipristis Posted December 19, 2023 Share Posted December 19, 2023 Oyster. Lol 'Those who cannot remember the past are condemned to repeat it.' George Santayana Link to comment Share on other sites More sharing options...
Lone Hunter Posted December 19, 2023 Author Share Posted December 19, 2023 Oysters are funny? Am I missing the joke? 1 hour ago, hemipristis said: Oyster. Lol Link to comment Share on other sites More sharing options...
Ludwigia Posted December 19, 2023 Share Posted December 19, 2023 9 hours ago, Lone Hunter said: so they both grew together? The baby oyster attached itself, used the ammonite as hardground and grew on it. Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
Lone Hunter Posted December 19, 2023 Author Share Posted December 19, 2023 Thank you @Ludwigia! The oyster looks quite old, would it have outlived the ammonite? What causes them to eventually separate? Link to comment Share on other sites More sharing options...
Al Dente Posted December 19, 2023 Share Posted December 19, 2023 1 hour ago, Lone Hunter said: Thank you @Ludwigia! The oyster looks quite old, would it have outlived the ammonite? What causes them to eventually separate? Oyster larvae attach to hard surfaces. In this case it attached to an ammonite shell that was most likely dead and laying on the sea bottom. They probably became separate when the aragonite shell of the ammonite dissolved after burial, during the fossilization process. The oyster shell is calcite which is more stable than aragonite. 1 Link to comment Share on other sites More sharing options...
Lone Hunter Posted December 19, 2023 Author Share Posted December 19, 2023 Great explanation @Al Dente, thank you I was trying to imagine this little ammonite lugging around the cumbersome oyster, makes sense it was dead. Link to comment Share on other sites More sharing options...
Ludwigia Posted December 19, 2023 Share Posted December 19, 2023 2 hours ago, Lone Hunter said: Thank you @Ludwigia! The oyster looks quite old, would it have outlived the ammonite? What causes them to eventually separate? I don't think we'll ever know who lived longest. They may have first separated after they were fossilized, or one could even have been bumped off the other while they were still alive....or somewhere between the two....oops...I see Al Dente beat me to it and his answer is much better than mine. Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
Lone Hunter Posted December 19, 2023 Author Share Posted December 19, 2023 I like your answer too it's just more imaginative. Surely sometimes the spat attached to live things, wonder if the ammonite were alive if it considered the oyster something of a parasite and would try to get rid of it. Link to comment Share on other sites More sharing options...
hemipristis Posted December 20, 2023 Share Posted December 20, 2023 On 12/19/2023 at 12:51 AM, Lone Hunter said: Oysters are funny? Am I missing the joke? Sorry, what I was attempting to relay was my ignorance in identifying individuals from this group of bivalves. All of my “oyster” fossils are labeled thusly: “Oyster.” 'Those who cannot remember the past are condemned to repeat it.' George Santayana Link to comment Share on other sites More sharing options...
Lone Hunter Posted December 20, 2023 Author Share Posted December 20, 2023 Totally get it. I believe there are some 80 species of oysters just in Texas. I bet I have a third of them and trying to nail down ID is frustrating to say the least. So yeah, oyster Link to comment Share on other sites More sharing options...
hemipristis Posted December 21, 2023 Share Posted December 21, 2023 7 hours ago, Lone Hunter said: Totally get it. I believe there are some 80 species of oysters just in Texas. I bet I have a third of them and trying to nail down ID is frustrating to say the least. So yeah, oyster Oyster IDs making speciating Carcharhinus teeth easy by comparison, imho 1 'Those who cannot remember the past are condemned to repeat it.' George Santayana Link to comment Share on other sites More sharing options...
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