SHORT-STEMMED EOCRINOIDS OF THE MIDDLE CAMBRIAN KAILI BIOTA,GUIZHOU PROVINCE, CHINA

Among Middle Cambrian Lagerstätten with soft-bodied preservation the Kaili Biota is unique because it is dominated by large numbers of (eocrinoid) echinoderms. Two basic body plans are represented by only two species. Sinoeocrinus lui has a long flexible stem, small attachment disc, elongate theca and long straight brachioles that streamed in elongate bundles in the current. Three times more abundant is "Sinoeocrinus globosa;" its stem is short, thick, composed of many small platelets, and flares distally into a broad, flat, polyplated attachment disc. The theca is broadly ovoid with large epispires that form early in ontogeny. The brachioles (10 in adults) extend from the typical 2-1-2-pattern ambulacrum and coil into loose curls a short distance from their base. Food grooves are consistently located on the inside of the curls. Current flowing over the brachiole is broken up into slowed turbulent flow and food particles are thereby more likely to be captured by the ciliary-mucoid surfaces of the greatly enlarged cover plates and the food groove. The globose theca and curled brachioles produce a great deal of hydrodynamic drag and it is countered by the unusually large attachment disc. "Sinoeocrinus globosa" is commonly gregarious and two to four individuals may be attached to a brachiopod shell or to trilobite exuviae. This species defines the second tier (8 to 15 mm) above the basal tier (0-8 mm, brachiopods, hyoliths), and is capped by the third tier (15 to 30 mm+, S. lui, sponges). The "S.globosa" bauplan is not unique to the Kaili; a slightly older species, Gogia ojenai, is known from the L. Cam. Latham Shale in California. These species are well adapted for living in turbid conditions above non-bioturbated fine-grained siliciclastic sea bottoms