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Name:
Glyptocrinus dyeri, Edrioasteroids
Age: Ordovician
Formation: McMillan Formation
Location: Kenton County, Kentucky
Size: Plate is 5.3 inches across
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Here is an extremely collectible plate of Ordovician echinoderms. This slab of crinoids and edrios is from the McMillan Formation of Kentucky. There are three fully inflated examples of Glyptocrinus dyeri on the plate. These camerate crinoids have a large, urn-shaped cup with extremely stellate plates. The long, thin, uniserial arms are wonderfully splayed, and the many fine pinnules are beautifully displayed. All of the crinoids have lengthy portions of stem tightly attached to the cups. But the coolest feature of two of the crinoids is that they have distinct gastropods feeding on the anal openings! The snails (Cyclora) are very easily seen (see close-up photo). There is also a brachiopod on the plate with FOUR EXAMPLES OF TWO DIFFERENT TYPES OF EDRIOASTEROIDS ATTACHED (two Isorophus cincinnatiensis and two Carneyella pilea). Edrioasteroids were primitive echinoderms which consisted of a flexible theca composed of numerous polygonal plates. In this specimen, the large edrioasteroids have attached itself to a brachiopod. This is probably not a symbiotic relationship, nor was the brachiopod under attack - the aragonitic/calcitic shell of the brachiopod merely provided a hard substrate for the edrioasteroid to rest upon. This is one of the most unusual and distinct specimens of Ordivician echinoderms we have ever seen.
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