A NEW BOURGUETICRINID (CRINOIDEA) FROM THE CASTLE HAYNE FORMATION

            Although several species of comatulid crinoids have been described from the Castle Hayne Formation (Emmons 1858; Ciampaglio & Weaver 2004), its stalked forms have been largely overlooked. Careful examination of a prepared bryozoan-echinoid calcirudite from the Martin Marietta Quarry near Castle Hayne, New Hanover County (North Carolina, USA), has yielded over 1,000 specimens, mainly cups and columnals, of a new species of gracile bourgueticrinid, Democrinus simmsi species nov.

            The middle Eocene Castle Hayne Limestone in North Carolina is well known for its abundant and varied invertebrate fauna. While much work has been performed on echinoids found within the Castle Hayne Limestone, other echinoderm taxa such as ophiuroids, asteroids, and crinoids have been collected by several workers but not published upon. This may be due in part to the small size of the non-echinoid echinoderms and the difficulty of isolating, recognizing, and identifying these faunal elements.

            This is especially true of crinoids, where the poor fossil record of the bathycrinids, including the bourgueticrinids, in the Cenozoic of the Americas is certainly, at least in part, due to taphonomic factors coupled with resultant collection failure. Extant bathycrinids are gracile and small, a typical mature adult specimen perhaps being about 100 mm high. Complete crinoids, or even just near-complete crowns, are very rare fossils and it is much more likely for a bathycrinid to enter the rock record as a myriad of small disarticulated ossicles.

            This is the first nominal bourgueticrinid from the Paleogene of North America, despite their moderate diversity locally in the Paleogene of Eurasia. The small size of cups and disarticulated columnals of gracile bourgueticrinids are almost certainly a factor in our poor knowledge of their fossil record.