2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 13
Presentation Time: 11:00 AM


STANLEY Jr, George D.1, SANDERSON, Angela C.1, HOU, X.-G.2 and CHEN, Ailin3, (1)Dept. Geology, Univ. Montana, Missoula, MT 59812, (2)Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming, 650091, China, (3)Chengiang Fauna Museum, Chengjiang, 652500, China, crystaline_flame@yahoo.com

The celebrated Early Cambrian Chengjiang biota of southwestern China has yielded some exquisite and extraordinary fossils. These fossils have provided important and unparalleled insights into the biology, taxonomic diversity and nature of the Cambrian explosion. While arthropods and other hard-shelled fossils are well known, considerable soft-bodied components of this biota also have been discovered. Among these newly discovered taxa are a whole assemblage of in situ anemones preserved on the bedding surface, replete with attachment disc, column, tentacles and crown. Also found are an abundance of possible hydroids on the bedding planes. Extremely fragile gelatinous taxa belonging to the phyla Cnidaria and Ctenophora are present as well. Pelagic taxa among the gelatinous biota include a possible jellyfish-like siphonophoran with tentacles and gonozooids and also several examples of ctenophores. The ctenophores are the oldest yet known. They are easily recognized as ctenophores because they still retain their eight comb-rows, cilia plates and associated gelatinous soft tissues. Compared to some other soft-bodied taxa, they are unique in preserving details of the delicate soft tissues and gelatinous material of the original living organisms. These fossils also provide valuable information on anatomy and body organization, connecting these 530 million-year old organisms with their distant living relatives. The striking degree of anatomical similarity at high taxonomic levels between some of these Early Cambrian taxa and their extant counterparts, hints at a much older origin in the late Precambrian for the ancestors of these groups.