The Ediacaran Avalon biota: New insights from old fossils

Alex G. Liu
University of Cambridge

In recent years, substantial progress has been made in constraining the phylogenetic affinities of fossils of the Ediacaran macrobiota, with both metazoan and non-metazoan clades now recognised amongst latest Ediacaran global fossil assemblages. However, the oldest palaeocommunities of the Ediacaran macrobiota - those of the ~574-557Ma Avalon assemblage - have proven particularly challenging to interpret. Here I will summarise ongoing palaeontological, taphonomic, palaeoecological and palaeoenvironmental research from Newfoundland, Canada, showcasing the record of macroscopic life in the oceans prior to the appearance of the 'classic' Ediacara biota taxa of South Australia and the White Sea. Recent findings permit identification of trends in biodiversity and morphology through the frond-dominated, largely deep-water Avalonian palaeocommunities, and provide key lines of evidence for tracing the earliest stages of eumetazoan evolution. The implications of recent radiometric dates for our understanding of the links between Newfoundland's Ediacaran biota and broader regional and global environmental events, including the Gaskiers glaciation and the Shuram anomaly, will also be discussed.