Vase-shaped microfossils from the late Ediacaran Dengying Formation of Ningqiang, South China: taxonomy, preservation and biological affinity

Abstract

The origin and early evolution of protists are shroud in misty. The oldest evidence of heterotrophic protists may be the vase-shaped microfossils (found in Early Neoproterozoic sedimentary rocks around the world (c. 780–720 Ma). Here we explore the taxonomy, preservational types and biological affinity of three-dimensionally preserved vase-shaped microfossils (VSMs) from the Gaojiashan biota of the Dengying Formation, Ningqiang, China. Five species and two genera are recognized, namely Protolagena limbata, P. gaojiashanensis, P. papillata, Sicylagena formosa and S. latistoma. SEM-EDS-BSE data provide sound evidence of calcareous and agglutinated tests of these VSMs. In addition, Found in siltstone beds and clastic dolomite, sedimentological data suggest these VSMs inhabited a series of preservational types including calcification, silicification, phosphatization and pyritization. The fossiliferous strata have recently been dated with U-Pb age of 548 ± 8 Ma, which indicates they are not coeval with diverse vase-shaped microfossil assemblages described in other regions worldwide, but provides supportive evidence for the early diversification of possible protozoa foraminifera clades follow on the Gaskiers Snowball Earth event (c. 590–580 Ma).