Discussion of Precambrian metazoans

Among conservation deposits, the Vendian occurrences of Ediacara-type fossils stand out for reasons other than their formidable age. They are unique because soft-bodied organisms are preserved not as organic or permineralized films in fine-grained sediments, but as threedimensional impressions on (and sometimes in) sandstones. Also, they do not reflect unusual physiographic ‘accidents’, but occur in ordinary sediments, representing well agitated conditions, all over the world. Nor are they restricted to a certain sedimentary regime, since similar impressions have now been found in shallow-marine tempestites as well as deep-water turbidites. We deal rather with a time signature that has no counterparts in the Phanerozoic record