Platycrinites & Camptocrinus Crinoid Association

This is an association of two different crinoid species from the famous Crawfordsville, Indiana crinoid beds. The crown (upper-right) is Platycrinites brevinodus and the other crinoid is Camptocrinus crawfordsvillensis. The quality of preparation on this fossil is exquisite - using skillful air-abrasion techniques under a stereo microscope.

It is believed that crinoids from the Edwardsville Formation were buried in sediment from nearby deltas during storms. The resulting siltstone deposits are soft enough that fossils can be extracted in exquisite, three-dimensional relief.