Nano-Scale Spheroids and Fossils from the Ediacaran Doushantuo Formation in China

Abstract

Exceptionally preserved nano-scale spheroids derived from microbial processes and nano-scale fossils have been discovered from the black shales of the Jijiawan section of the Ediacaran Doushantuo Formation in the Yangtze Gorge area of Hubei Province, southern China. The numerous soccer ball-like spheroids are pyritized. Their morphology and abundant preservation may suggest that they could possibly be related to larger spheroids, regardless of the tremendous dimensional gap found in the phosphorite and cherts of the Doushantuo Formation, including those recognized as ‘embryos’. The colony-like spheroids preserved in situ and obtained by acid maceration are compared with known Neoproterozoic microfossils—Bavlinella faveolata (or Sphaerocongregus variabilis). Additionally, nano-scale fossil bodies, characterized by morphological features comparable to living cyanobacteria, fungi and possible unicellular heterotrophic protists were observed in different minor laminae of the black shale samples. This study aims to reveal the aspects of nano-scale biota preserved in the black shale of the Ediacaran Doushantuo Formation, and highlight the taphonomy of microorganisms during the key transition from the anoxic deeper oceans to the oxygenated oceans of the early Ediacaran interval.