MEDUSIFORM FOSSILS FROM THE MIDDLE MIDDLE CAMBRIAN JIALAO FORMATION OF JIANHE COUNTY, GUIZHOU, CHINA
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Abstract:
Medusiform eldoniids, which are a group of pelagic animals with coiled alimentary canal and tentacles, are confined to the Cambrian, especially in lower to middle Cambrian of Poland, Spain, Siberia, North America and South China, etc. Eldoniids are one of important components of the three Burgess Shale-type hiotas, including the Chengjiang Biota, Kaili Biota and Burgess Shale Biota. Here we describe a medusiform fossil from the middle Cambrian Jialao Formation at Balang village, Gedong Town, Jianhe County, Guizhou Province. Although the fossil has the similar features as eldoniids with bifurcated lobes, the poor preservation of a single specimen makes it premature to assign it to a genus or species. The undefined genus and species is discoid in shape with 32-36 rough radial lobes. The fossil horizon is about 1 fossil zone above that of Pararotadiscus guizhouensis from the Kaili Biota. Based on the study of trilobites, the geological age is middle middle Cambrian. It is the highest horizon of eldoniids in China. In the past, the exceptional preservation of soft-bodied fossils was often discovered in the mudstone, and was infrequent in the carbonate. Thus this occurrence in the Jialao Formation is an important evidence of soft-bodied fossils in the carbonate. The medusiform fossil reported here provides new information of the Cambrian life.
