INSIGHTS INTO THE PRODUCER OF 'FOERSTE'S BEADS' (ECHINODERMATA: CRINOIDEA) BASED ON NEW MATERIAL FROM THE LOWER SILURIAN BRASSFIELD FORMATION OF CENTRAL KENTUCKY

The Lower Silurian Brassfield Formation crops out throughout eastern midcontinent North America as a prominent carbonate deposit representing a variety of shoal to shallow shelf environments. The upper portion of this unit throughout Ohio and Kentucky is characterized by the exceptional abundance of a distinctive crinoid columnal that has historically been referred to as a “bead.” Although recognized for over a century, the taxonomic identity of the crinoid responsible for production of these elements is unknown; this is due largely to the taphonomic state of “beads,” which are nearly always preserved as isolated columnal ossicles and have not historically been discovered as articulated segments or in association with identifiable calyx plates or arm segments. Recently discovered material from central Kentucky 1) allows these columnals to be confidently attributed to the morphogenus Floricolumnus, 2) permits recognition of these elements as components of a coiled dististelar attachment structure, and 3) reveals an association between “beads” and crown material, namely an appropriately large basal circlet and small, uniserial, pinnulate brachials. Collectively, this material supports the interpretation that the producer of these columnals is a large diplobathrid camerate, likely a dimerocrinitid.