NOTES ON THE OLDEST FOSSIL BIVALVES FROM THE NIUTITANG FORMATION OF FUQUAN,GUIZHOU
Shu De-gan(Department of Geology, Northwestern University)
In this paper are reported two species of bivalves from the Niutitang Formation in Fuquan county, Guizhou, namely, Xianfengoconcha elliptica Zhang and X. elongata sp. nov., with obvious lamellar teeth. They might be included in the same lineage with the bivalves found from Xianfeng, Hubei. As compared with those bivalves found in the Early Cambrian all over the world, the present species are regarded as the oldest of all forms ever known before, and therefore, they are of great importance in the study of the origin and phylogeny of the Bivalvia.