关键词: 早寒武世, 澄江化石库, 鳃曳动物, 活化石

Abstract: Most of their clades of the Priapulan terminated their evolutionary history immediately after their rapid diversification in the Early Cambrian, probably due to the constriction of many factors such as body plan, life style etc. However, Cambrian priapuomorphs convincingly resemble their recent descendents, supporting that this clade remain stagnant in morphology, and really being a kind of living fossils either in anatomical or molecular level. This evolutionary feature, together with recent findings of priapulans-like fossil embryos, is rather critical to investigate into the origin of the metamorphosis of metazoans. 

Key words:  Early Cambrian, Chengjiang Lgerstatte, priapulans, living fossils