JamieLynn Posted June 22, 2021 Share Posted June 22, 2021 In Central Texas you don't have to go very far to find fossils. But the Austin Chalk Formation is a little tricky finding good spots which are fairly fossiliferous. Fortunately, the Paleontological Society of Austin visits a couple of good spots and the fossiling was pretty decent this time, because we've had some good rains! This particular creek is really lovely, too....white limestone with green ferns and even some Mustang Grapevines! Although it was a hot day (as per the usual in Texas Summertime) the creek was at least shady and a bit cool and it felt great to stick my feet in the water to cool off, all the while keeping an eye out for that good fossil....... The Exogyra Oysters are the main thing found here, but there is a special one called a tigrena that have some of the original coloring on them. They are really fascinating, with their "tiger" stripes! 1 1/2 inch 2 1/4 inch 2 1/4 inch This one has both valves. 1 1/2 inch Nautiloids and ammonites are there, but rare. I happily procured one small slightly squished and not very well preserved nautiloid. 3 inches (one of the other PSoA members found a perfect little one, in a recent rock fall. He was faster up the creek than I was!) And this beauty was found even further upstream by my friend Melvin who let me borrow it to photograph. I thought y'all might like to see it. I think it is a Barrioceras dentatocarinatum Size 3 inches And one more big honking Oyster; Exogyra erraticostata 5 inches Wild Mustang Grapevines! 3 13 www.fossil-quest.com Link to comment Share on other sites More sharing options...
Pagurus Posted June 22, 2021 Share Posted June 22, 2021 I do like the color on those oysters. It looks like a fine place to hunt. Those Texas summers are too hot for me though. Thanks for sharing your trip. 1 1 Start the day with a smile and get it over with. Link to comment Share on other sites More sharing options...
Reebs Posted June 22, 2021 Share Posted June 22, 2021 (edited) Lovely finds in a beautiful setting. Thanks for sharing. Edited June 22, 2021 by Reebs Spelling Link to comment Share on other sites More sharing options...
JohnJ Posted June 22, 2021 Share Posted June 22, 2021 Great images, Jamie! Rather than Exogyra erraticostata (which displays more radial 'crinkling'), I think the 5 incher is Exogyra laeviuscula Roemer. 3 The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
JamieLynn Posted June 22, 2021 Author Share Posted June 22, 2021 1 hour ago, JohnJ said: Great images, Jamie! Rather than Exogyra erraticostata (which displays more radial 'crinkling'), I think the 5 incher is Exogyra laeviuscula Roemer. Really? I thought laeviscula were smoother? In the HGMS book it shows erraticostata with more crenulations, but also one with more irregular crinkling. (Pic not from the HGMS book, but I think they were drawn from this: This is laeviuscula, pretty sure. www.fossil-quest.com Link to comment Share on other sites More sharing options...
JohnJ Posted June 22, 2021 Share Posted June 22, 2021 Check Finsley's book. The geology is also a good match for your other finds. 1 The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
erose Posted June 23, 2021 Share Posted June 23, 2021 I think the Dessau is too old for erraticostata. If it wasn’t for the extra coiling i would have suggested ponderosa. Link to comment Share on other sites More sharing options...
DPS Ammonite Posted June 23, 2021 Share Posted June 23, 2021 Charles Newsom lists an Exogyra erraticostata in the Dessau Member. You still need to look at the professional literature since Newsom is not a paleontologists. Not enough crinkles for your Exogyra to be an erraticostata. I believe that it is spelled tigrina. http://homepage.physics.uiowa.edu/~cnewsom/fossils/Oysters/exogyra/ 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...
JamieLynn Posted June 24, 2021 Author Share Posted June 24, 2021 7 hours ago, erose said: I think the Dessau is too old for erraticostata. If it wasn’t for the extra coiling i would have suggested ponderosa. well, I was actually originally going by what Ed told me. He said erraticostata, so I was going with that. www.fossil-quest.com Link to comment Share on other sites More sharing options...
erose Posted June 24, 2021 Share Posted June 24, 2021 16 minutes ago, JamieLynn said: well, I was actually originally going by what Ed told me. He said erraticostata, so I was going with that. Ed knows his stuff…gonna look that up now Link to comment Share on other sites More sharing options...
DPS Ammonite Posted June 24, 2021 Share Posted June 24, 2021 (edited) Some consider Exogyra erraticostata to be Exogyra ponderosa var. erraticostata. https://www.mindat.org/taxon-9039904.html Stephenson who first described Exogyra ponderosa var. erraticostata said that there is a complete intergradation of ornamentation (costa) from Exogyra ponderosa to Exogyra costata. Since your Exogyra contains no traces of costa, I would call it a plain Exogyra ponderosa. See original description on page 49 https://pubs.usgs.gov/pp/0081/report.pdf Stephenson, L. W., 1914, Cretaceous deposits of the eastern Gulf region and species of Exogyra from the eastern Gulf region and the Carolinas: U.S. Geol. Survey Prof. Paper 81, p. 9-40. Edited June 24, 2021 by DPS Ammonite 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 June 24, 2021 Share Posted June 24, 2021 On 6/22/2021 at 5:11 PM, JohnJ said: Great images, Jamie! Rather than Exogyra erraticostata (which displays more radial 'crinkling'), I think the 5 incher is Exogyra laeviuscula Roemer. Sticking to Exogyra laeviuscula. From Finsley's, A Field Guide to Fossils of Texas: The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
DPS Ammonite Posted June 24, 2021 Share Posted June 24, 2021 (edited) 9 minutes ago, JohnJ said: Sticking to Exogyra laeviuscula. From Finsley's, A Field Guide to Fossils of Texas: The beak curl may make it an Exogyra laeviuscula. If it is considered a ponderosa variety (or sister species) then it is not an erraticostata based on lack of costata. I consider Finsley’s book to be less reliable than the professional journal literature. Finsley told me shortly before he died that he had lots of corrections to make in the book, but they would have to be made by someone else. Oysters are notoriously difficult to ID due to their great variability. Charles Newsom had his own different ideas from Finsley on the Exogyra and Texigryphaea ID’s. http://homepage.physics.uiowa.edu/~cnewsom/fossils/Oysters/index.html Edited June 24, 2021 by DPS Ammonite 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...
erose Posted June 24, 2021 Share Posted June 24, 2021 I also believe the extra coiling would make this a closer match to E. laeviscula. And boy-boy nothing like some oysters to make one nuts with identifications... 1 2 Link to comment Share on other sites More sharing options...
JamieLynn Posted June 24, 2021 Author Share Posted June 24, 2021 @JohnJ @erose and @DPS Ammonite I want to thank all of y'all for taking the time to share your information. That's what I love about this site.... I learn stuff ALL the time! 1 2 www.fossil-quest.com Link to comment Share on other sites More sharing options...
fifbrindacier Posted June 25, 2021 Share Posted June 25, 2021 Thank you to show us this spot Jamie, it seams you had a great trip. "On ne voit bien que par le coeur, l'essentiel est invisible pour les yeux." (Antoine de Saint-Exupéry) "We only well see with the heart, the essential is invisible for the eyes." In memory of Doren Link to comment Share on other sites More sharing options...
Jared C Posted May 15, 2023 Share Posted May 15, 2023 reviving this chat with an exogyra question... Is anyone aware of the stratigraphic range of E. eratticostata? I'm wondering about its usefulness as an index fossil, specifically for the Pflugerville member. @erose @JohnJ @Uncle Siphuncle I have a Kau site I'm trying to confirm the member on, but can't cement any ID's for the ammonites I've seen there. UT's guidebook to the geology of travis county has this to say about E. eratticostata's occurrence in the Pflugerville, but doesn't say anything about the range of these oysters. "The Pflugerville Member is named for the village of Pflugerville north of Austin, Travis County, where the formation underlies the Immanuel Lutheran Church. The type locality is selected at the curve in Cameron Road on levels (presumably bedding planes) at which Exogyra erraticostata and Actinostreon travisana (Stephenson) are concentrated." “Not only is the universe stranger than we think, it is stranger than we can think” -Werner Heisenberg Link to comment Share on other sites More sharing options...
JohnJ Posted May 15, 2023 Share Posted May 15, 2023 From Austin Chalk In Its Type Area - Stratigraphy And Structure, Young and Woodruff 1985 7 hours ago, Jared C said: I'm wondering about its usefulness as an index fossil, specifically for the Pflugerville member. Not exclusive, but a good indicator. 2 1 The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted May 15, 2023 Share Posted May 15, 2023 Lovely photos and beautiful fossils. I'm glad that someone bumped the thread and I finally got to see it! Very interesting discussion, too. Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
Jared C Posted May 15, 2023 Share Posted May 15, 2023 2 hours ago, JohnJ said: From Austin Chalk In Its Type Area - Stratigraphy And Structure, Young and Woodruff 1985 Thanks for sending this, I tried to find a copy but it seems to be out of stock everywhere “Not only is the universe stranger than we think, it is stranger than we can think” -Werner Heisenberg Link to comment Share on other sites More sharing options...
JohnJ Posted May 15, 2023 Share Posted May 15, 2023 2 hours ago, JohnJ said: From Austin Chalk In Its Type Area - Stratigraphy And Structure, Young and Woodruff 1985 From the same publication: 1 1 The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
Jared C Posted May 15, 2023 Share Posted May 15, 2023 2 minutes ago, JohnJ said: From the same publication: you have no idea how helpful this was, thank you!! “Not only is the universe stranger than we think, it is stranger than we can think” -Werner Heisenberg Link to comment Share on other sites More sharing options...
JohnJ Posted May 15, 2023 Share Posted May 15, 2023 1 minute ago, Jared C said: you have no idea how helpful this was, thank you!! Yeah, I do. 2 1 The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
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