The question of the developmental characters which conventionally define the vertebrates, neural crests and epidermal placodes, and their indirect identification in the fossil material is briefly discussed. Comments are made upon some presumed Cambrian vertebrate or vertebrate-related taxa, with particular reference to the most likely Cambrian vertebrates, Haikouichthys and Myllokunmingia.
Vertebrates, Cambrian, anatomy, phylogeny, neural crest, epidermal placodes