CRINOIDS AND MARINE REPTILE FOSSILS FROM THE GUANLING FAUNA OF THE UPPER TRIASSIC (CARNIAN) WAYAO FORMATION, GUIZHOU PROVINCE, SOUTH CHINA

Abundant fossils including a diverse assemblage of crinoids, marine reptiles, fish, ammonoids, bivalves and conodonts were recently recovered from the "Guanling Fauna" a spectacular Lagerstätte in the Wayao Formation in Guanling County, Guizhou Province. The Wayao Formation is composed of dark-gray to black, laminated marly lime mudstone and calcareous shale containing abundant organic matter and feromanganese nodules. Crinoids and marine reptiles occur on bedding planes and are articulated with exquisite preservation of fine detail. Sedimentary features and fossil preservation indicate the Wayao Formation was deposited in an anoxic marine setting in water depths possibly in excess of 500m. The occurrence of the conodonts Paragondolella polygnathiformis, P. foliata, and P. navicula, and the ammonoid Trachyceras multuberculatum indicate a Late Triassic (Carnian) age. Mu Enzhi(1949) first reported exquisitely preserved large criniods in the Guanling area. Our studies have identified the large crinoid species, Traumatocrinus hsui Mu, Traumatocrinus guanlingensis Yu, which may represent some of the first articulate crinoids. The crinoids range up to 1m tall with crowns up to 20 cm across; some occur in "thickets" essentially in growth position. Since 1998 our studies have yielded over 100 nearly complete marine reptile specimens including Sauropterygians, Placodonts, and Ichthyosaurs: Neosinasaurus hoangiZhou, Wayaosaurus geei Zhou, Wayaosaurus bellus Zhou, Placodelys? minutus Yin and Luo, Mixosaurius guanlingensis Cao, Xinpisaurus suni Yin, Guizhouichthyosaurus tangae Cao and Luo, Typicusichthyosaurus tsaihuae Yu, Guanlingsaurus liangae Yin, Qianichthyosaurus zhoui Li, Although the overall characteristics of these marine reptiles are similar to Tethyan ones, they display transitional character between the Triassic and Jurarassic-Cretaceous marine reptiles, possess obvious regional characteristics, and are extraordinary in their abundance, diversity and nearly perfect preservation. The "Guanling fauna"may be a unique Lagerstätte. Further detailed study of this fauna, promises major contributions to paleoecology, paleotaphonomy, evolution, and taxonomy of marine reptiles and crinoids.