Revision of the Chen and Yao Devonian to Permian crinoids from Western Yunnan

摘要

In 1993, Chen and Yao described the first major Paleozoic echinoderm faunas reported from China. Restudy of these Middle and Late Devonian, Early Carboniferous, and Early Permian faunas collected from the Basoshan tectonic block of western Yunnan resulted in some systematic and paleogeographic revisions. The Baoshan block originated on the northern part of Gondwana at about 30°S latitude in the Devonian and Carboniferous, drifted away in the Early Permian, and docked with Cathaysia by the Late Triassic, becoming part of South China. Devonian and Early Carboniferous crinoids lived in a carbonate shelf environment, but Early Permian faunas lived in a colder water glaciogene environment. The Devonian and Mississippian faunas are more closely related to coeval European faunas than they are to North American faunas. The Yunnan Devonian and Mississippian faunas are camerate dominated, with few cladids, and lack flexible crinoids. As currently recognized, Middle Devonian endemic crinoids of western Yunnan are Shidianocrinus, Parascyphocrinites, Ovalocrinus, and Quasicydonocrinus. Early Carboniferous endemics of western Yunnan are Yunnanocrinus and Parabarycrinus. The crinoids in the Yudong Formation support a Tournaisian age for these crinoidal rich beds. The stratigraphic range of Stomiocrinus is extended downward into the Tournaisian. Shidianocrinus is reassigned to the Dimerocrinitidae and Parascyphocrinites is reassigned to the Melocrinitidae. Parabarycrinus is reassigned to the Gasterocomidae. New combinations are Ectocrinus anthodeus, Cantharocrinus sphaeroides, Rhodocrinites intermedius, Rhodocrinites excavatus, Rhodocrinites baoshanensis, Holcocrinus irregularis, and Separocrinus discoides. New taxa introduced are Amphoracrinus cheni n. sp., Synbathocrinus yaoi n. sp., and Platycrinites s.s. langbaensis n. sp.