The terminal Ediacaran tubular fossil Cloudina in the Yangtze Gorges area of South China

Abstract

The advent of biomineralizing metazoans in the terminal Ediacaran Age (ca. 550–539 Ma) represents a remarkable biological innovation in the history of life. As a poster child of this evolutionary episode, Cloudina is widely regarded as a weakly biomineralizing tubular fossil with a global distribution. Therefore, Cloudina can both inform the evolution of animal biomineralization and facilitate terminal Ediacaran stratigraphic correlation. However, this key taxon has not been fully described from the Yangtze Gorges area of South China, where classical terminal Ediacaran strata have been investigated extensively by paleontologists, stratigraphers, and geochemists. Here we document an assemblage of three-dimensionally silicified tubular fossils from siliceous dolostone of the terminal Ediacaran Baimatuo Member of the Dengying Formation in the Yangtze Gorges area, western Hubei Province, South China. The Baimatuo assemblage consists of Sinotubulites (which has been previously known in the Baimatuo Member), as well as Cloudina (including C. ningqiangensis, C. hartmannae, C. cf. carinata, and C. sp. indet.) and other unnamed tubular forms. This discovery adds to the diversity of early biomineralizing metazoans in the Yangtze Gorges area and facilitates the biostratigraphic correlation of the Cloudina–Sinotubulites co-occurrence assemblage in terminal Ediacaran strata.