BobWill Posted October 15, 2018 Share Posted October 15, 2018 I found this plate of oysters I don't know the name of in the Lower Cretaceous Grayson Formation exposure at Rayzor Ranch in Denton Texas. I showed it to @trempie4 in August and @Jeffrey P when he was here in September and neither one wanted it so I finally took it home myself. As I was exposing more of the oysters I first noticed these nice little serpula on and around the oysters. Then I noticed something I haven't seen before. i wonder if it could be some kind of feeding trace. Any ideas? 1 Link to comment Share on other sites More sharing options...
Heteromorph Posted October 15, 2018 Share Posted October 15, 2018 Weird, haven’t a clue. But very interesting! Link to comment Share on other sites More sharing options...
daves64 Posted October 15, 2018 Share Posted October 15, 2018 Ultra ancient rock art. Accomplishing the impossible means only that the boss will add it to your regular duties. Link to comment Share on other sites More sharing options...
Raggedy Man Posted October 15, 2018 Share Posted October 15, 2018 The coiled piece could be a crinoid. illustration is from: "Crinoid anchoring strategies for soft-bottom dwelling", 2005, Seilacher and MacClintock. Palaios vol. 20. There is also a paper specific to holdfasts from the Silurian of Gotland but doesn't really identify to species. That paper is "Crinoid holdfasts from the Silurian of Gotland", 1977, Franzen. Lethaia vol. 10. ...I'm back. Link to comment Share on other sites More sharing options...
KimTexan Posted October 15, 2018 Share Posted October 15, 2018 It looks like a form of Bryozoa. I have not come across that variety before, but I have come across others in the Cretaceous. Possibly @erose or @BobWill will know. I have hunted the Grayson in Hurst numerous times, but the Razor Ranch area briefly one time. 2 Link to comment Share on other sites More sharing options...
BobWill Posted October 15, 2018 Author Share Posted October 15, 2018 45 minutes ago, Raggedy Man said: The coiled piece could be a crinoid. illustration is from: "Crinoid anchoring strategies for soft-bottom dwelling", 2005, Seilacher and MacClintock. Palaios vol. 20. There is also a paper specific to holdfasts from the Silurian of Gotland but doesn't really identify to species. That paper is "Crinoid holdfasts from the Silurian of Gotland", 1977, Franzen. Lethaia vol. 10. Interesting illustration. Since this is from the Cretaceous I guess crinoid would be a pretty unlikely Id and the worm tubes are common here. It's really the other structures I'm wondering about. Wouldn't mind knowing the name of these oysters either. I see them occasionally but never looked for an ID. Link to comment Share on other sites More sharing options...
TqB Posted October 15, 2018 Share Posted October 15, 2018 They are bryozoans, maybe Herpetopora or Pyripora. Here's something similar on a UK Belemnitella - just the attachment bases of the chains of zooids which were fragile. . 4 Tarquin Link to comment Share on other sites More sharing options...
Raggedy Man Posted October 15, 2018 Share Posted October 15, 2018 7 hours ago, BobWill said: Interesting illustration. Since this is from the Cretaceous I guess crinoid would be a pretty unlikely Id and the worm tubes are common here. It's really the other structures I'm wondering about. Wouldn't mind knowing the name of these oysters either. I see them occasionally but never looked for an ID. Ah sorry about. I figured id chime in the thing I could help with...lol. ...I'm back. Link to comment Share on other sites More sharing options...
DPS Ammonite Posted October 15, 2018 Share Posted October 15, 2018 @BobWill Do you have any of these oysters free of matrix in order to help get a better ID? Are these the interior of the top (smaller shell) of an oyster. 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...
BobWill Posted October 15, 2018 Author Share Posted October 15, 2018 Thanks for the ID TqB and KimTexan. 7 hours ago, DPS Ammonite said: @BobWill Do you have any of these oysters free of matrix in order to help get a better ID? Are these the interior of the top (smaller shell) of an oyster. John, I believe these are the left valve. The right valve is thin and flat. Here are some that I think are the same showing the left valves. A and B and maybe part of D seem to have grown up against ammonites or something showing a bioimmuration impression. C is probably what they would look like otherwise. Here are the right valves of D and A and B with a missing right valve. Link to comment Share on other sites More sharing options...
erose Posted October 15, 2018 Share Posted October 15, 2018 18 hours ago, KimTexan said: It looks like a form of Bryozoa. I have not come across that variety before, but I have come across others in the Cretaceous. Possibly @erose or @BobWill will know. I have hunted the Grayson in Hurst numerous times, but the Razor Ranch area briefly one time. I would ID them as bryozoa as well. There was some work recently on Cretaceous bryozoans including some Texas varieties. I'll have to dig up the paper and get back to yall. The coiled thing is most likely a serpulid tube. Again a large variety of them with only a few having been studied and named. Link to comment Share on other sites More sharing options...
DPS Ammonite Posted October 16, 2018 Share Posted October 16, 2018 There are about 3 medium sized oysters in the Grayson Fm. that I have seen. I cannot easily tell them apart: Exogyra clarki; Exogyra drakei and a Pycnodonte. Are Bob's one of these? Can anyone tell them apart? @JohnJ @Uncle Siphuncle 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...
JohnJ Posted October 16, 2018 Share Posted October 16, 2018 From the images posted, it's hard to make much more than a guess. It would probably be best for Bob to compare to the scientific descriptions of those mentioned. 10 minutes ago, DPS Ammonite said: There are about 3 medium sized oysters in the Grayson Fm. that I have seen. I cannot easily tell them apart: Exogyra clarki; Exogyra drakei and a Pycnodonte. Are Bob's one of these? Can anyone tell them apart? @JohnJ @Uncle Siphuncle The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
BobWill Posted October 16, 2018 Author Share Posted October 16, 2018 10 minutes ago, DPS Ammonite said: There are about 3 medium sized oysters in the Grayson Fm. that I have seen. I cannot easily tell them apart: Exogyra clarki; Exogyra drakei and a Pycnodonte. Are Bob's one of these? Can anyone tell them apart? @JohnJ @Uncle Siphuncle I have also found some very similar in the Duck Creek, just never had occasion to identify them. 1 minute ago, JohnJ said: From the images posted, it's hard to make much more than a guess. It would probably be best for Bob to compare to the scientific descriptions of those mentioned. None of the images I've looked at include the sharply squared-off margin these share. Honestly I am only guessing that they are even oysters and I don't know if all the ones I showed are the same, but all of those on the slab probably are. They may also exhibit some bioimmuration since the outermost surfaces are not all the same shape. Maybe they all grew up against something large and are shown upside-down. Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted October 16, 2018 Share Posted October 16, 2018 Sorry guys, I honestly haven't put much time into oysters beyond using them to find other target fossils. Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
DPS Ammonite Posted October 16, 2018 Share Posted October 16, 2018 The similiar oysters from the Duck Creek are probably Exogyra corrugata. I have a real love hate relation with Texas Cretaceous oysters. They have great preservation often with both valves present, but they are very difficult to identify if you do not know the exact formation since they vary in shape due to environmental conditions. There are localities at Lake Texoma where you can find oysters from the Mainstreet and the Grayson Formations that vary so much in shape that they look like different species of oysters that only occur in the half dozen or so formations below. I suspect that your Grayson oysters are Texigryphea or Pychnodonte species with really large attachment scars. One person that might help is Charles Newsom, retired University of Iowa professor, who has studied Texas Cretaceous oysters. Contact him, you might get some interesting answers: Charles-newsom@uiowa. edu. http://homepage.physics.uiowa.edu/~cnewsom/fossils/index.html https://www.priweb.org/index.php/research/research-awards/katherine-palmer-award/2011-charles-ray-newsom http://homepage.physics.uiowa.edu/~cnewsom/fossils/Oysters/ilymatogyra/Exogyra-plexa.html 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...
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