AN OVERVIEW OF PALEOZOIC STEMMED ECHINODERMS FROM CHINA

Accurate studies of diversity, evolution, extinction, and biogeographic affinities of fossil communities and fossil clades through time depend on taxonomically sound, global databases. Stemmed echinoderms, or pelmatozoans, were significant members of marine communities for most of the Paleozoic. They have been well studied in Europe and North America, Australia, and to a lesser extent, northern Africa. However, historic reports of pelmatozoans other than stem taxa from Asia are uncommon, despite the abundance of Paleozoic-aged rocks in Asia. This situation creates an incomplete and biased view of the evolution, extinction, and biogeographic affinities of these groups of echinoderms, which include crinoids and blastoids, through the Paleozoic. Existing collections, a survey of the literature, and our own field experiences show that diverse and significant echinoderm faunas do exist in China, and should be included in discussions of extinction, rebound, and paleobiogeography. China is a mosaic of plate fragments, microcontinents, and accretionary wedges. China contains part or all of numerous substantial continental blocks, including Tarim, Sino-Korea Yangtze Junggar, Kazakstania, Angara,Indochina, Sibumasu, as well as smaller continental fragments, and accretionary complexes that have coalesced since the mid-Paleozoic. Echinoderm fossils found in this diverse collage generally occur in areas of platform and shelf sedimentation on the margins of larger continental blocks such as Sino-Korea, Yangtze, and Sibumasu. However, echinoderms also have been collected from sedimentary accretionary wedge facies on what were active plate margins between Kazakstania/northern Junggar, and southern Junggar/Tarim. These terranes were situated on both the northern and southern margins of Paleo-Tethys and have complex temporal, spatial, and climatic relationships. Because certain echinoderms tend to be highly endemic, their geographic distribution within faunas can play extremely important roles in delineating paleogeographic positions of these terranes through time.