Abstract

The non-availability of biomineralized skeletons and low levels of predation led Vendian evolution along strange avenues. The Ediacara-type Vendobionta appear to represent a kingdom, in which foliate shapes, large sizes and the necessary compartmentalization were achieved by quilting of the skin rather than by multicellularity. Psammocorallia, in contrast, are interpreted as coelenterates that constructed an internal sand skeleton. Both were immobile soft-bottom dwellers that had high population densities, and both became preserved by obrutional accidents; thus they render ‘fossil snap shots’, in which the original distributional patterns, age structures and standing biomasses of populations are accurately recorded.