PhD: The Ediacaran biota in miniature: palaeoecological and palaeobiological insights from sub-centimetre fossils

Fossils of the Ediacaran macrobiota are found globally in strata of ~580–539 million years in age, and offer a remarkable record of the early evolution of complex, macroscopic organisms. Determination of the precise phylogenetic positions of Ediacaran taxa is critical to our understanding of two major evolutionary events, namely the rise of complex multicellularity, and the origin and early diversification of animals. Some of the oldest known assemblages of Ediacaran macrofossils are found in Newfoundland (Canada). These fossils are particularly problematic, with many species possessing frondose body plans that share few morphological similarities with modern taxa. In recent years, novel studies into growth and palaeoecology have offered important insights into the biology of Ediacaran taxa, providing constraints on their potential phylogenetic positions. However, such studies rely on the availability of well-preserved juvenile specimens, which until now have been particularly rare components of the fossil assemblages.

This project will provide the most accurate picture of Ediacaran palaeocommunities yet obtained, via investigation of growth and palaeoecology within recently discovered, exceptionally preserved, fossil assemblages of small (less than 30mm length) specimens of Ediacaran macrofossil taxa from Newfoundland. Small specimens reflect a significant but largely undocumented component of Ediacaran marine palaeoenvironments, and include both known and undescribed taxa. This project will characterize intra- and inter-specific interactions within palaeocommunities, and test hypotheses regarding reproduction and community development. A primary focus will be to elucidate the role of filamentous connective structures in Ediacaran ecosystems. Additional assessment of ontogeny and development amongst specific taxa will aim to constrain their phylogenetic affinities.

The student will collect palaeobiological data from existing collections of casts and laser scan datasets at the University of Cambridge, and from field sites, to assess spatial and temporal ecological interactions amongst Ediacaran macrofossil taxa. Measurements of morphological features within populations will be used to investigate ontogeny and reproduction. Spatial Point Process Analyses (SPPA) will detect intra- and inter-specific competition, permitting assessment of the role of small specimens in community development. The project will involve visits to field sites in Newfoundland, Canada, including the Mistaken Point Ecological Reserve UNESCO World Heritage Site, and the Catalina Dome on the Bonavista Peninsula. Certain casts will be studied using x-ray tomography (micro-CT scanning) to obtain sub-millimetric morphological data. The project could potentially be expanded to consider local-scale biogeochemical interactions between these organisms and their environments.