galaxy777 Posted July 30, 2013 Share Posted July 30, 2013 Please excuse my lack of knowledge yet on many types of fossils, but are these Crinoid plates? These were found (in abundance) in Post oak creek and Choctaw creek in Grayson Co. Texas. I think it is from the Woodbine group, but please correct me on which group or formation of a group if I'm wrong. I'm still wet behind the ears on formations. I really need to get that geography book.. Link to comment Share on other sites More sharing options...
rejd Posted July 30, 2013 Share Posted July 30, 2013 I don't see any signs of crinoids in these. I am sure someone here will let you know for sure. A fossil hunter needs sharp eyes and a keen search image, a mental template that subconsciously evaluates everything he sees in his search for telltale clues. -Richard E. Leakey http://prehistoricalberta.lefora.com Link to comment Share on other sites More sharing options...
Foshunter Posted July 30, 2013 Share Posted July 30, 2013 That formation is way too young for crinoids, you have a mineral formation. Maybe some more verse in them can give you an answer. Have hunted both creeks, some nice fossils can be found there, bet it's hot this time of the year----Tom Grow Old Kicking And Screaming !!"Don't Tread On Me" Link to comment Share on other sites More sharing options...
FossilDAWG Posted July 30, 2013 Share Posted July 30, 2013 Your specimens are not crinoid plates, they most likely are pieces and fragments of inoceramid bivalve shells. The fibrous structure is characteristic. Crinoid plates are made of calcium carbonate, and fracture to reveal flat crystal cleavage plane surfaces. Also, crinoid plates are more-or-less hexagonal; even if broken you can see that they are fragments of hexagons. Innoceramids were often very large, flat shells that readily break into a myriad of irregularly shaped pieces. Also some of your photos (the second one in particular) show encrusting oysters that commonly grew on the larger inoceramids. Don Link to comment Share on other sites More sharing options...
galaxy777 Posted July 30, 2013 Author Share Posted July 30, 2013 Thank you FossilDawg for identifying these things. It makes sense, considering I never found any crinoid stems too. I wonder what they would look like tumbled? Link to comment Share on other sites More sharing options...
vertman Posted July 30, 2013 Share Posted July 30, 2013 Also the geology of those creeks is not Woodbine. You are looking at a mixture of Lower Austin Group and Upper Eagle Ford Group sediments all mixed up in there. The Woodbine outcrops further to the west of where you were most probably collecting. Link to comment Share on other sites More sharing options...
galaxy777 Posted July 30, 2013 Author Share Posted July 30, 2013 Thank you Vertman for clarifying what formation's I'm looking in. I'm still clueless on the geography. Link to comment Share on other sites More sharing options...
Indy Posted July 30, 2013 Share Posted July 30, 2013 Hey guys and gals ... I don't live in TX Share the time periods with the formation names ... Flash from the Past (Show Us Your Fossils)MAPS Fossil Show Link to comment Share on other sites More sharing options...
BobWill Posted July 30, 2013 Share Posted July 30, 2013 That's the Eagle Ford Formation in Upper Cretaceous for y'all non-Texans:) The ones with flanges look like broken pieces of septarian nodules which can be found in Post Oak Cr. Link to comment Share on other sites More sharing options...
erose Posted July 30, 2013 Share Posted July 30, 2013 That's the Eagle Ford Formation in Upper Cretaceous for y'all non-Texans:)The ones with flanges look like broken pieces of septarian nodules which can be found in Post Oak Cr. I think photo two and six are Pseudoperna congesta. They are small oysters that would cover inoceramids. Very classic Austin Chalk (Upper Cretaceous) fossils. Link to comment Share on other sites More sharing options...
Herb Posted July 31, 2013 Share Posted July 31, 2013 (edited) What Don says. Crinoids were not real common in the Cretaceous. Edited July 31, 2013 by Herb "Absence of evidence is not evidence of absence"_ Carl Sagen No trees were killed in this posting......however, many innocent electrons were diverted from where they originally intended to go. " I think, therefore I collect fossils." _ Me "When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes "can't we all just get along?" Jack Nicholson from Mars Attacks Link to comment Share on other sites More sharing options...
BobWill Posted July 31, 2013 Share Posted July 31, 2013 I think photo two and six are Pseudoperna congesta. They are small oysters that would cover inoceramids. Very classic Austin Chalk (Upper Cretaceous) fossils. I agree after opening the pic for a good look, thanks. Link to comment Share on other sites More sharing options...
galaxy777 Posted July 31, 2013 Author Share Posted July 31, 2013 Thank you all for helping me to identify these clam pieces and the oysters that covered them; plus the formations they are in. Yes, I have come across quite a few septarian nodule's along Post Oak and Choctaw creek. I bought several home for my rock garden. Link to comment Share on other sites More sharing options...
.thumb.JPG.d64a00de120fb553baacff5149461632.JPG)
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now