PENIS WORMS AND THEIR RELATIVES IN THE EARLIEST CAMBRIAN PERIOD

Morphological phylogenetic analysis suggests that priapulids (“penis” worm), loriciferans, and kinorhynchs form the clade Scalidophora, which is closely related to nematoids and arthropods. Together, these ecdysozoans phyla account for a significant portion of animal diversity. However, their early evolutionary history has not been completely resolved, despite the abundance of Cambrian ecdysozoans fossils in the Chengjiang and Burgess Shale biotas. We report the discovery of three-dimensionally preserved scalidophoran fossils from Fortunian (early Cambrian) rocks of South China. The new fossils preserve detailed anatomies about their proboscis, scalids, and pharyngeal teeth. The new fossils help us to resolve the sequence of character acquisitions along the evolutionary path toward modern scalidophorans.