File:Parascytalocrinus hamiltonensis & Sarocrinus sp. (fossil crinoids) (Edwardsville Formation, Lower Mississippian; Crawfordsville, Indiana, USA) 1 (33509207534).jpg

Parascytalocrinus hamiltonensis (Worthen, 1882) & Sarocrinus sp. - fossil crinoids from the Mississippian of Indiana, USA. (rock is 6.1 centimeters across at its widest)

Large crinoid head at center = Parascytalocrinus hamiltonensis

Small crinoid head at left = Sarocrinus sp.

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.

This slab has two intact crinoid heads from the famous Crawfordsville crinoid fauna in Indiana, which is well known for its abundance of exceptionally preserved, articulated fossil crinoids and other echinoderms. This crinoid occurrence is one of the most spectacular on Earth - it contains at least 63 different crinoid species (Ausich, 1999), many of which are quite sizable.

I won this fossil piece as a doorprize at last night's 75th anniversary meeting of the Dry Dredgers in Cincinnati, Ohio (<a href="http://drydredgers.org" rel="nofollow">drydredgers.org</a>). The Dry Dredgers is the oldest fossil collecting club in America. Over 100 people were in attendance, including professional paleontologists from as far away as Michigan, Florida, and California. In celebration of the anniversary meeting, over $1000 worth of fossil doorprizes were available. I was floored when my ticket number was called out. I rarely win stuff, and life has been handing me a lot of lemons lately. This was a pleasant surprise! This has a retail value of $125.

Classification of Parascytalocrinus: Animalia, Echinodermata, Crinoidea, Cladida, Dendrocrinida, Scytalocrinidae

Classification of Sarocrinus: Animalia, Echinodermata, Crinoidea, Cladida, Zeacrinitidae

Stratigraphy: Edwardsville Formation, Osagean Stage, upper Lower Mississippian

Locality: fossil quarry near Crawfordsville, Montgomery County, western Indiana, USA

Reference cited:

Ausich, W.I. 1999. Lower Mississippian Edwardsville Formation at Crawfordsville, Indiana, USA. pp. 145-154 in Fossil Crinoids. Cambridge, U.K. Cambridge University Press.

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