Ontogeny, morphology and taxonomy of the soft‐bodied Cambrian ‘mollusc’ Wiwaxia

@article{Smith2014OntogenyMA,
  title={Ontogeny, morphology and taxonomy of the soft‐bodied Cambrian ‘mollusc’ Wiwaxia},
  author={Martin R. Smith},
  journal={Palaeontology},
  year={2014},
  volume={57}
}
The soft‐bodied Cambrian organism Wiwaxia poses a taxonomic conundrum. Its imbricated dorsal scleritome suggests a relationship with the polychaete annelid worms, whereas its mouthparts and naked ventral surface invite comparison with the molluscan radula and foot. 476 new and existing specimens from the 505‐Myr‐old Burgess Shale cast fresh light on Wiwaxia's sclerites and scleritome. My observations illuminate the diversity within the genus and demonstrate that Wiwaxia did not undergo discrete… 
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New reconstruction of the Wiwaxia scleritome, with data from Chengjiang juveniles

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The scleritome arrangement and constitution in this material corroborates the link between Orthrozanclus and Halkieria, but not with Wiwaxia — and calls into question its purported relationship with molluscs.

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Brachiopods hitching a ride: an early case of commensalism in the middle Cambrian Burgess Shale

This association of Nisusia with the motile Wiwaxia is interpreted as the oldest unambiguous example of a facultative ectosymbiosis between a sessile organism and a mobile benthic animal in the fossil record, and suggests that symbiotic associations were already well established and diversified by the “middle” Cambrian.

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