The Barren EN2 Is Not Barren: Microfossils from the Ediacaran Doushantuo Formation at Shennongjia-Baokang Area Filling the Biostrat-Igraphic Gap

The negative carbon isotope excursion EN2 in the Ediacaran Doushantuo Formation of South China has traditionally been considered a “fossil-barren zone,” impeding microfossil biostratigraphic correlation. However, integrated litho-, chemo- and biostratigraphic analyses from multiple shallow-water inner shelf sections in the Shennongjia-Baokang area (e.g., Lianhuacun, Sanlihuang, Yanyacun) reveal abundant microfossils preserved in chert nodules/bands precisely within the EN2 interval. These include diverse acanthomorphic acritarchs, sphaeromorphic fossils, cyanobacteria, and multicellular algae. Our findings demonstrate that the so-called “barren zone” is a taphonomic artifact. The fossil assemblage can be correlated with the third acritarch assemblage zone of South China, or potentially represents a new transitional assemblage zone. Thus, the EN2 is not barren; it fills critical paleontological gaps in shallow-water facies and enables a more complete biostratigraphic framework for the early Ediacaran.