Comatula pinnata Goldfuss, 1831 - fossil stemless crinoid in fine-grained limestone from the Jurassic of Germany. (public display, Orton Geology Museum, Ohio State University, Columbus, Ohio, USA)

This species is also known as Antedon pinnata and (apparently) Pterocoma pinnata.

Crinoids (sea lilies) are sessile, benthic, filter-feeding, stalked echinoderms that are relatively common in the marine fossil record. Crinoids are also a living group, but are relatively uncommon in modern oceans. A crinoid is essentially a starfish-on-a-stick. The stick, or stem, is composed of numerous stacked columnals, like small poker chips. Stems and individual columnals are the most commonly encountered crinoid fossils in the field. Intact, fossilized crinoid heads (crowns, calices, cups) are unusual. Why? Upon death, the crinoid body starts disintegrating very rapidly. The soft tissues holding the skeletal pieces together decay and the skeleton falls apart.

The crinoid shown here is from the famous Solnhofen Limestone, a deposit that includes soft-part preservation. The number one most famous fossil on Earth came from Solnhofen - Archaeopteryx, which is literally half-reptile, half-bird (creationists hate that fossil). The Solnhofen is a lagoon deposit that has marine, nonmarine, and marginal marine organisms, including animals and plants.

Unlike Paleozoic crinoids, this Solnhofen crinoid was stemless/stalkless. Most crinoids in modern oceans similarly lack a stem. Juvenile specimens show evidence of cirri that were used to anchor the individual to substrates. Adult specimens may have been capable of swimming through the water by undulating their arms.

Classification: Animalia, Echinodermata, Crinoidea, Articulata, Comatulida

Stratigraphy: Solnhofen Limestone, Upper Jurassic

Locality: unrecorded/undisclosed site in Bavaria, Germany

See info. at: <a href="https://en.wikipedia.org/wiki/Comatulida" rel="nofollow">en.wikipedia.org/wiki/Comatulida</a> and