danco Posted August 18, 2011 Share Posted August 18, 2011 (edited) I am confused what genus could be all these bivalvia? Can somebody help me? They are from Sherman TX (Grayson county), Cretaceous, Austin Fm. The largest is 6.7 cm tall. Thank you. Edited August 18, 2011 by danco Link to comment Share on other sites More sharing options...
jkfoam Posted August 18, 2011 Share Posted August 18, 2011 Danco, They look more like Plicatula than Lopha to me. The Lopha have a real exagerated zig-zag structure at the margin of the shell. We really need a photo of the inside of a couple of valves to see what the hinge and adductor scar looks like. JKFoam The Eocene is my favorite Link to comment Share on other sites More sharing options...
tracer Posted August 18, 2011 Share Posted August 18, 2011 i have considered them to be lopha b. bellaplicata, from the contact between the upper eagle ford with the basal austin chalk. and i felt like they were subadult versions of that species since i found them in the same location as the classic larger versions. but now i guess i'm wondering. but the reference i'm referencing doesn't mention the formation i found them in as being plicatulescian in persuasion, so i'm thinking i'll stick with lopha until i get some sort of cease-and-desist notification. Link to comment Share on other sites More sharing options...
erose Posted August 18, 2011 Share Posted August 18, 2011 (edited) The Upper Cretaceous Plicatula species listed that high up in the section all have finer ribs and more ornamentation. There are several Lophas to consider. Some are listed for the Eagle Ford and others the Navarro and Taylor. You said Austin Fm. The Austin Group can represent a lot of time so were you high or low in the section? I've been looking at the HGMS book because someone just gave me a really nice Lopha panda collected in the Burditt Fm. which is upper Austin Group. But it is definitely different than what you have there. The two contenders in my opinion would be: Lopha bellaplicata bellaplicata (Shumard, 1860B) and Lopha lugubris lugubris (Conrad, 1857). They are really nice specimens and in having a nice selection you should be able to nail them down with just a bit more information. Edited August 18, 2011 by erose Link to comment Share on other sites More sharing options...
danco Posted April 1, 2012 Author Share Posted April 1, 2012 Hi erose, Sorry for the delay but I was abroad. Maybe you can tell me more knowing that Sherman fossils belong lower Upper Cretaceous formations. Thank you for your precious help. Link to comment Share on other sites More sharing options...
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