Rockwood Posted December 30, 2017 Share Posted December 30, 2017 Found on a coal shale dump near Jolliette, PA. Fresh water bivalves ? Marine bivalves washed in during a transgression ? Or could they be Branchiopods ? Other ? Link to comment Share on other sites More sharing options...
Peat Burns Posted December 30, 2017 Share Posted December 30, 2017 Perhaps Paleoneilo sp. ? (Bivalvia) Link to comment Share on other sites More sharing options...
westcoast Posted December 30, 2017 Share Posted December 30, 2017 Certainly bivalve. My first guess about carboniferous bivalves is always Carbonicola but it is just a guess. Bivalves can be very tricky. Somebody with experience of your area will be able to help. Link to comment Share on other sites More sharing options...
Fossildude19 Posted December 30, 2017 Share Posted December 30, 2017 These actually look like conchostracans to me. (Clam shrimp) Something similar to Cyzicus or Estheria. Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
TqB Posted December 30, 2017 Share Posted December 30, 2017 I'm not honestly sure how you can tell from first principles that they aren't bivalves but I agree with Tim. They look like ones I've seen that other people have told me are Estheria. Tarquin Link to comment Share on other sites More sharing options...
westcoast Posted December 30, 2017 Share Posted December 30, 2017 I'm seriously doubting my already doubt- riddled contribution now.. Link to comment Share on other sites More sharing options...
Rockwood Posted December 30, 2017 Author Share Posted December 30, 2017 16 minutes ago, TqB said: first principles Refers to the form of preservation, or would a few more examples help ? Link to comment Share on other sites More sharing options...
TqB Posted December 30, 2017 Share Posted December 30, 2017 Very difficult to tell just by looking if they're chitinous or not. But they look like conchostracans. I'm just wondering, as in your original post, if there are juvenile/dwarf bivalve molluscs that are effectively indistinguishable. Tarquin Link to comment Share on other sites More sharing options...
Rockwood Posted December 30, 2017 Author Share Posted December 30, 2017 13 minutes ago, TqB said: Very difficult to tell just by looking if they're chitinous or not. But they look like conchostracans. I'm just wondering if there are juvenile/dwarf bivalve molluscs that are effectively indistinguishable. I see. Pesky convergence, sort of has me. Thanks Link to comment Share on other sites More sharing options...
jdp Posted December 30, 2017 Share Posted December 30, 2017 As others have suggested, these are conchostracans. They're pretty common in the freshwater Carboniferous and Permian shales of Pennsylvania, which is exactly where you are finding them. They indicate that the environment where the rocks were deposited had lots of temporary water pools that would flood part of the season but be dry during other parts of the season. That sort of severe seasonal climate (a "megamonsoon") is characteristic of the late Carboniferous. Link to comment Share on other sites More sharing options...
westcoast Posted December 30, 2017 Share Posted December 30, 2017 3 minutes ago, jdp said: As others have suggested, these are conchostracans. They're pretty common in the freshwater Carboniferous and Permian shales of Pennsylvania, which is exactly where you are finding them. They indicate that the environment where the rocks were deposited had lots of temporary water pools that would flood part of the season but be dry during other parts of the season. That sort of severe seasonal climate (a "megamonsoon") is characteristic of the late Carboniferous. Can you point out the salient ID features in the pics above to help with future possible ID's as I'm sure I may have overlooked conchostracans in the past. Thanks. Link to comment Share on other sites More sharing options...
jdp Posted December 30, 2017 Share Posted December 30, 2017 For one, not all of them are complete, and when they broke down (prior to deposition), they seem to have broken along the ridges rather than cracking like a clam shell would. Additionally, the concentric ridges do not always extend uninterrupted across the entire animal. Finally, there is no interdigitating tooth structure in the valve where the two sides would have met. If these were clams, you'd also expect to see a separate calcitic shell in there as well, instead of simply glossy impressions. Link to comment Share on other sites More sharing options...
marguy Posted December 31, 2017 Share Posted December 31, 2017 a monograph of the fossil Estheriae by T Rupert Jones, London , 1862 pdf available here: https://www.biodiversitylibrary.org/bibliography/52947#/summary obviously, it's old, but with interesting texts and figures… Link to comment Share on other sites More sharing options...
westcoast Posted January 1, 2018 Share Posted January 1, 2018 Thanks to this thread I have re-examined some of my samples that were destined to be ignored and I think I can now say deserve more study and some may actually be conchostracans. I'm hoping for a glimpse of an appendage.... Link to comment Share on other sites More sharing options...
Ash Posted January 1, 2018 Share Posted January 1, 2018 Having found conchostracans before..they sure look the same as mine. "Faith is to believe what you do not see; the reward of this faith is to see what you believe" - Saint Augustine"Those who can not see past their own nose deserve our pity more than anything else." Link to comment Share on other sites More sharing options...
deutscheben Posted January 2, 2018 Share Posted January 2, 2018 I will join the chorus in agreement about the clam shrimp ID- the genus Leaia is commonly associated with Pennsylvanian plant fossils in central Illinois, and look very similar to these. Link to comment Share on other sites More sharing options...
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