Doushantuo-pertatataka-type acanthomorphs and ediacaran ecosystem stability

Large (100 to ~700 μm diameter) spheroidal carbonaceous microfossils ornamented with regularly arranged spinose or branched processes are globally distributed in the Ediacaran (635-542 Ma). These microfossils, collectively known as the Doushantuo-Pertatataka-type acanthomorphs, have been variously interpreted as a polyphyletic assortment of resting stages of eukaryotes, including animals. The stratigraphic range of the acanthomorphs has long been thought to be restricted to the interval between the uppermost Cryogenian glacial deposits and the largest-known carbon isotope excursion in Earth's history, the Shuram event. The mid-Ediacaran disappearance of the acanthomorphs was puzzling until they were discovered in younger strata in south China, in northwestern Russia, and in Mongolia. Here, we report Doushantuo-Pertatataka-type acanthomorphs coeval with Cambrian-type small skeletal fossils. It appears that neither the Shuram event nor the emergence of macroorganisms, eumetazoans, and biologically controlled mineralization significantly affected the acanthomorphs, suggesting a marked stability of Ediacaran ecosystems up to the very beginning of the Cambrian.