Figure 4 Representative Proterozoic and Early Cambrian acritarchs. A–C and the specimen on the left in D are spheromorphic; the specimen on the right in D and E–H are acanthomorphic. (A) Le iosphaeridia sp., Mesoproterozoic [M1] McMinn Formation, Australia. (B) Leiosphaeridia crassa, Neoproterozoic [N2] Miroyedikha Formation, Siberia. (C) Kildinosphaera verrucata, Miroyedikha Formation. (D) Shuiyousphaeridium macroreticulata (Left ) and Dictyosphaera incrassata (Right), late Mesoproterozoic [M3] Baicaoping Formation, China. (E) Trachyhystrichosphaera aimika, Neoproterozoic [N4] Draken Formation, Svalbard. (F) Tanarium densum, Neoproterozoic [N7] Doushantuo Formation, China. (G) Tanarium conoideum, Neoproterozoic [N7] Kursovsky Formation, Siberia. (H) Skiagia ciliosa , Early Cambrian [C4] Tokammane Formation, Svalbard. (Bar in E: A–C and H, 25 µm; D and G, 60 µm; E, 300 µm; G, 100 µm)

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