Molecular biology has re-opened the debate on metazoan diversification, including the vexing question of the origin of the major body plans (phyla). In particular, sequence analyses of rRNA have reconfigured significantly metazoan phylogeny, while homeobox genes suggest there could be an underlying similarity of developmental instructions in nominally disparate phyla. Despite this dramatic progress I argue that this renaissance of activity is lop-sided, but can be redressed by palaeontological data, especially from the Cambrian and immediately preceding Vendían. The fossil record complements and amplifies the conclusions derived from molecular biology, notably in the early radiation of cnidarians (Ediacaran faunas) and key steps in the diversification of the protostomes.

Keywords:
Cambrian, Ediacaran, evolution, fossil, Metazoa, phylogeny
© 1994 by Company of Biologists
1994
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