Skeletogenesis in problematic Late Proterozoic Lower Metazoa

Abstract

This paper discusses supporting structures in problematic Late Precambrian Lower Metazoa, sponge and cnidarian affinity. These structure include aggregates of agglutinated mineral particles; spicule-like elements; mineralized spicules, long fibrous fiberlike elements; dense covers-thecae(?); monolithic and module organic and mineralized structures. In clastic deposits, mineralized remains could probably be absent, due to anoxic conditions characteristic of the Late Proterozoic shelf environment. As a hard skeleton is part of the archetype of many Phanerozoic taxa, the analysis of such structures allows discussion of the body plans and phylogeny of some elements of the Ediacaran “fauna” interpreted as lower Metazoa.