File:Ectenocrinus simplex (fossil crinoid heads) (Kope Formation, Upper Ordovician; Carrollton, Kentucky, USA) 3.jpg

English: Ectenocrinus simplex (Hall, 1847) - fossil crinoids from the Ordovician of Kentucky, USA.

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 fossils seen here eroded from a fossiliferous megarippled limestone horizon in the Upper Ordovician of Kentucky. The segmented structures are intact crinoid heads of Ectenocrinus simplex. Multiple, articulated crinoid heads were found together, indicating rapid burial of a thicket of Ectenocrinus crinoids. They occupied an ancient, relatively shallow seafloor and were knocked down by a storm event and buried. Limestone beds representing storm events are called tempestites.

Classification: Animalia, Echinodermata, Crinoidea, Disparida, Homocrinidaee

Stratigraphy: Southgate Member, middle Kope Formation, middle Edenian Stage, lower Cincinnatian Series, lower Upper Ordovician

Locality: hillslope exposure at the southeastern corner of the Interstate 71-Route 227 intersection (next to Interstate 71's exit 44), south of the town of Carrollton, central Carroll County, northern Kentucky, USA (38˚ 38.772' North latitude, 85˚ 07.022' West longitude)

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Info. at:

en.wikipedia.org/wiki/Crinoid