Fig. 7

Schematic drawings showing morphology, relative sizes and boundaries of the protegulum, brephic shell, neanic shell and mature shell. a planktotrophic larva of Eohadrotreta with pitted protegulum, brephic shell and larva setae (modified from [11, 15]). b-c ventral and dorsal juveniles of Eohadrotreta from the Cambrian (Series 2) Shuijingtuo Formation of South China. d-e ventral and dorsal juveniles of Siphonobolus from the Cambrian (Furongian) of Iran (modified from [28]). f dorsal juvenile of Eoobolus from the Cambrian (Series 2) of Canada (modified from [29]). g-h ventral and dorsal juveniles of Micromitra from the middle Cambrian of Turkey (modified from [26]). i juvenile of Mickwitzia from Cambrian (Series 2) of Canada (modified from [62]). j-k ventral and dorsal juveniles of Salanygolina from the Cambrian (Series 2) of Mongolia (modified from [46]). l dorsal juvenile of Oslogonites from Meddle Ordovician of Russian (modified from [36]). Abbreviations: bs, brephic shell; ha, halo; lse, larval setae; mas, mature shell; ms, metamorphic shell; mse, marginal mantle setae; np, nick points; ns, neanic shell; pr, protegulum; ps, post-metamorphic shell; te, tentacle