RECONSTRUCTING 3D EDIACARAN FRONDS

Soft-bodied fronds dominated late Ediacaran (575-538 Ma) marine ecosystems and their fossils provide iconic images of the world’s first large (dm- to m-scale), abundant and globally distributed, morphologically complex eucaryotes. Most Ediacaran frondose fossils worldwide are preserved as flattened 2D impressions on the soles of event beds of sandstone or volcanic ash, but some of these impressions can yield information about both sides of the frond through composite molding or partial flipping of the fronds during preservation. Rare occurrences of Ediacaran fronds preserved within or at the top of turbulent sandstone event beds in Newfoundland, Namibia, and Australia reveal key additional information about the three-dimensional shape and structure of Ediacaran fronds through injection of sand between petaloids of multifoliate fronds, partial to complete casting of the inside of fronds, and orientation of fronds preserved at different angles within beds of fluidized sand. Study of a previously perplexing collection of dm-scale fronds from Ediacara shows how elucidating the taphonomy and three-dimensional morphology of these Ediacaran fronds significantly enhances our understanding of their life habits and taxonomic relationships.