Saturday, August 29, 2015
These pictures are what appear to be dorsal calyx cups from an Agassizocrinus fossil crinoid. The fossils were found in Glen Dean Member of Grayson County, Kentucky, USA. They date to Mississippian Period.
I have been wanting to find this type of fossil for a while and finally got a chance to collect some. They are small about the size of a marble and are in a distinctive cup shape with five segments.
My friend Dave talks about them on his fossil blog in a 2013 posting. He cites the this reference for more information: Index Fossils of North America, Shimer and Shrock, 1944 Edition on pages 175-176, plate 61.
A more complete one can be seen on Crinus's fossil web site: http://www.crinus.info/crinoids/data/agas.htm
Images take with a Moto G 2nd Generation phone.