debivort Posted April 10 Share Posted April 10 I feel like I should know what this, but am drawing a blank. Pennsylvanian limestone from the Pedernales park in Texas, USA. Roughly 2x4cm Link to comment Share on other sites More sharing options...
daves64 Posted April 10 Share Posted April 10 (edited) Cone in cone cross section? Edited April 10 by daves64 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...
Rockwood Posted April 10 Share Posted April 10 Oyster Rastellum 1 Link to comment Share on other sites More sharing options...
Ludwigia Posted April 10 Share Posted April 10 I don't think that Rastellum existed in the Pennsylvanian. They first appeared in the Jurassic as far as I know. 1 1 Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
Rockwood Posted April 10 Share Posted April 10 1 hour ago, Ludwigia said: I don't think that Rastellum existed in the Pennsylvanian. They first appeared in the Jurassic as far as I know. But if the shoe fits. Is the age given, correct? Link to comment Share on other sites More sharing options...
Ludwigia Posted April 10 Share Posted April 10 Sorry, but it doesn't exactly look like it to me. Maybe the OP can confirm the stratigraphy of the rock? Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
TqB Posted April 10 Share Posted April 10 (edited) I believe it's a section of crinoid stem showing weathered echinoderm calcite structure. They seem to be common in Pennsylvanian limestone there and the lithology looks right. Joints between columals arrowed, typical echinoderm cleavage showing well at the bottom: Edited April 10 by TqB 3 1 Tarquin Link to comment Share on other sites More sharing options...
Rockwood Posted April 10 Share Posted April 10 I guess the shoe doesn't fit and I get blisters. 1 Link to comment Share on other sites More sharing options...
debivort Posted April 10 Author Share Posted April 10 3 hours ago, Ludwigia said: Maybe the OP can confirm the stratigraphy of the rock? It's Marble Falls Limestone, exposed at Pedernales Falls. Bedrock, so I'm rather certain of the stratigraphy in this case. https://www.beg.utexas.edu/texas-through-time/pedernales-falls.html Crinoids are preserved there, in abundance. Here's one (about 1.8 x 10cm): The original photo shows the only V-patterning that I saw on any fossil. 1 1 Link to comment Share on other sites More sharing options...
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