ABSTRACT
We have collected a diverse, micromorphic, fossil-echinoderm fauna from Xinxu, northwest of Liuzhou, Guangxi Province, Peoples Republic of China. The fossils were collected from black mudstones of the upper part of the Luocheng Formation (mid-Carboniferous), which was deposited in a nearshore environment on a broad carbonate platform. This fossil assemblage is significant because it was collected near the mid-Carboniferous boundary, and because it is temporally and geographically intermediate between the well-documented Lower Carboniferous faunas from North America and Europe, the Permo-Carboniferous faunas from the Soviet Union, and the Permian fauna from Timor. The fauna is dominated both numerically and taxonomically by micromorphic gastropods (at least 15 genera), with lesser numbers of small bivalves, brachiopods, cephalopods, echinoderms (taxonomically the second most diverse group), and barnacle-bored mudstone pebbles. Echinoderms include fragments of blastoids, asteroids and echinoids as well as diverse crinoids. We have recovered fragments of flexible crinoids, platycrinid columnals, dichocrinid radiais, columnals of Camptocrinus, and cups and brachial fragments of poteriocrine inadunate genera. The echinoderms and gastropods are particularly well preserved, with protoconchs present on many gastropods and three-demensional, galleried stereom common in the echinoderms. Our efforts to date have been concentrated on the microcrinoids. The following microcrinoid genera have been identified from the Luocheng Formation: Amphipsalidocrinus, a micromorphic camerate; Litrocrinus, an allagecrinid; two streblocrinid genera — Neolageniocrinus and Dichostreblocrinus; Allocatillocrinus, a catillocrinid; and Passalocrinus, the inferred juvenile stage of blastoids. These genera have not been previously reported from China.
