First finds of problematic Ediacaran fossil Gaojiashania in Siberia and its origin

We describe the first occurrence of the problematic fossil Gaojiashania outside China, in the Ediacaran Yudoma Group of the Siberian Platform. In both areas, Gaojiashania characterizes the lower upper Ediacaran strata and precedes the appearance of Cloudina and other skeletal fossils, which highlights its significance for the Ediacaran subdivision and correlation. Features of this fossil such as indeterminate length, the absence of a distinct growth pattern, and self-avoiding behavior indicate its trace fossil origin but do not necessarily imply metazoan affinities for its producers. Several organisms including stem-group social amoebozoans and unicellular protists may have been Proterozoic trace fossil producers.