Lead supervisor: Nicholas J. Butterfield, Earth Sciences
Co-supervisor: Alex Liu, Earth Sciences
Brief summary:
The evolution of eukaryotes was one of the defining transitions in the evolution of life on Earth, but their pre-Ediacaran fossil record remains deeply challenging
Importance of the area of research concerned:
Eukaryotes account for most of the morphological and ecological complexity observed in the Phanerozoic biosphere but their earlier, pre-Ediacaran, fossil record remains deeply problematic. The oldest convincing evidence for such organisms are complex microfossils from around the Palaeo-/Mesoproterozoic boundary (1600 Ma), though it remains to be seen what these represent phylogenetically (are they crown-group or stem-group eukaryotes, for example?) or how they made a living. At the same time, there are regular claims for substantially older fossil eukaryotes, both microscopic and macroscopic. What exactly are the criteria for recognizing such organisms in the fossil record? How can they be distinguished from prokaryotes, or even artefacts of diagenesis (pseudofossils)? This project will take a deep dive into the issue of recognizing and interpreting early eukaryotic fossils – with important implications for understanding the origin of this revolutionary new domain.
Project summary :
The project will focus on two iconic Proterozoic fossil biotas: the ~1900 Ma Gunflint Chert, and the ~1500 Ma Greyson Formation (Belt Supergroup). Both preserve abundant microfossils, but with differing levels of confidence in terms of recognizing a eukaryotic grade of organization. Large populations of fossils (and fossil-like structures) will be assembled and analysed in order to assess their biological credentials. Sedimentological, petrographic and geochemical analyses will be conducted with an eye to resolving details of their palaeoenvironment and taphonomy. Together with an appreciation of modern microbial diversity, ecology and phylogenetics, this high resolution interrogation of the early fossil record will yield a substantially more nuanced understanding of early eukaryotic evolution.
What will the student do?:
The student will conduct detailed petrographic and palynological analyses of fossil assemblages in both the Gunflint Chert and Greyson mudstones. Comparison with modern and fossil counterparts will be a primary focus. The project can be taken in a number of directions depending on initial results and student interest. There are also opportunities to extend the work into other Proterozoic biotas.
References - references should provide further reading about the project:
Butterfield, N.J. 2015. Early evolution of the Eukaryota. Palaeontology 58, 5–17.
Porter, S.M. 2020. Insights into eukaryogenesis from the fossil record. Interface Focus 10, 20190105.
Adam, Z.R., Skidmore, M.L., Mogk, D.W. & Butterfield, N.J. 2017. A Laurentian record of the earliest fossil eukaryotes. Geology 45, 387–390.
Applying
You can find out about applying for this project on the Department of Earth Sciences page.