Fig. 3. Schematic of different possible times of protostome-deuterostome divergence (orange circles), in relation to other events in the late Neoprotoerozoic. In scenario 1 there is little incongruence between the fossil record and the time of divergence, which occurs following the second or Marinoan glacial interval. In scenario 2, the divergence occurs between the two glaciations, and in scenario 3, before the Sturtian glaciation. Both scenarios 2 and 3 imply a much longer missing interval of post-PDA history. A, Middle Cambrian Burgess Shale fauna; B, Lower Cambrian Chengjiang fauna; C, Diverse Ediacaran fauna; D, Doushantuo phosphorite assemblage (with poor age constraints shown by uncertainty in position). See text for more discussion.
