Fig. 4
Ontogenetic changes in trunk region of Fuxianhuia protensa during post-embryonic development. a Stage 8 is the earliest juvenile available, and possesses 4 thoracic limb-bearing tergites with short tergopleurae, followed by 4 limb-less cylindrical tergites. The three reduced anteriormost tergites under the head shield remain invariant. Throughout ontogenetic development, the most anterior abdominal tergite (pink) develops expanded pleurae and walking legs, transforming into the most posterior thoracic tergite (yellow). Tergite 7 arrowed in all stages for comparison. Stage 30b is the oldest known phase. b Partial trunk segmentation schedule for F. protensa; complete ontogenetic reconstruction provided in Fig. 11