New sites of Chengjiang fossils: crucial windows on the Cambrian explosion

Abstract

Soft-bodied and lightly sclerotized Chengjiang fossils have been found at more than ten new localities in the Lower Cambrian Qiongzhusi and Canglangpu formations of east central Yunnan. At the same time, three different fossil assemblages have been recognized, i.e. Kunmingella–Isoxys–Naraoia assemblage at Chengjiang, Kunmingella – Cricocosmia assemblage at Haikou, and Kunmingella – Wutingaspis – Obolus assemblage at Anning and Wuding. These sites yield new and striking specimens, such as a new tentacular animal, brachiopods with pedicles preserved, and the enigmatic Xidazoon (having mixed phyla characters), which are significant in our understanding of animal phylogeny. Above all, the appearance of diverse chordates and agnathans (vertebrates) greatly expands our knowledge of the Cambrian explosion. The discovery of soft-bodied fossils at many new localities and the very wide distribution of the Qiongzhusi Formation suggest that many more localities remain to be discovered. Here, a new early form of tentaculate, Cambrotentacus sanwuia gen. et sp. nov. (perhaps related to lophophorates and entoprocts), is described.