One or Three Cambrian Radiations?

@article{Balavoine1998OneOT,
  title={One or Three Cambrian Radiations?},
  author={Guillaume Balavoine and Andr{\'e} Adoutte},
  journal={Science},
  year={1998},
  volume={280},
  pages={397 - 398}
}
The Cambrian explosion was a time of great evolutionary change, especially in the appearance of organisms with bilateral symmetry. In their Research Commentary, Balavoine and Adoutte discuss recent findings that may allow a reinterpretation of animal phylogeny and may have a profound bearing on understanding of the Cambrian explosion. 
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Evo-Devo Course 2001 References
flatworms: Earliest extant bilaterian metazoans, not members of platyhelminthes.
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