Middle Ura Association of Organic-Walled Microfossils: the Lower Vendian of the Patom Basin, Siberia

Abstract A new assemblage of Early Vendian (Middle Ediacaran) microfossils, including acanthomorphic acritarchs and various filamentous remains, as well as sphaeromorphic striated vesicles of Valeria , which are not characteristic of deposits of this age, is described from the Ura Formation of the Dal’nyaya Taiga Group of the Patom Basin. A new species of acanthomorphs Hocosphaeridium crispum sp. nov. is recognised. The Ediacaran eukaryotic phytoplankton taphocoenoses are shown to be selectively restricted to the open-sea proximal facies of the inner ramp.