Very 3D Agaricocrinus Crinoid From Crawfordsville

This is a wonderful example of a relatively uncommon species of crinoid from Crawfordsville, Agaricocrinus americanus. The crown on this specimen is 1.5" in length with with a nice little section of it's still attached. 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.

The quality of preparation on this fossil - using skillful air-abrasion techniques under a stereo microscope - preserved the extremely fine pinnulation within the calyx that this crinoid needed to filter food from the water column.