2.2" Crinoid (Macrocrinus) Fossil - Crawfordsville, Indiana

This is a detailed Macrocrinus mundulus crinoid crown and stem from the famous crinoid beds near Crawfordsville, Indiana. The quality of preparation on this fossil is exquisite - using skillful air-abrasion techniques under a stereo microscope.

There looks to be a break between the two stem segments, indicating that this stem is either a composite (from another crinoid), or it has been remounted following the preparation process.

It is believed that crinoids from the Ramp Creek Limestone 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.

Crinoids, sometimes commonly referred to as sea lilies, are animals, not plants. They are echinoderms related to starfish, sea urchins, and brittle stars. Many crinoid traits are like other members of their phylum. Such traits include tube feet, radial symmetry, a water vascular system, and appendages in multiples of five (pentameral). They first appeared in the Ordovician (488 million years ago) and some species are still alive today.

Macrocrinus mundulus
Crawfordsville, Indiana
Edwardsville Formation
2.2" long (stem included) on 3.4 x 1.6" rock
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