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Cambridge NERC Doctoral Training Partnerships

Graduate Research Opportunities
 

Lead Supervisor: Alex Liu, Earth Sciences

Brief summary: 
This project seeks to resolve the phylogenetic affinities of problematic Cambrian fossils that bear morphological similarities to late Ediacaran taxa.
Importance of the area of research concerned: 
The rise and diversification of the major animal phyla across the Ediacaran–Cambrian boundary is one of the most important evolutionary events in the history of life on Earth. Many questions regarding the patterns and drivers of evolution across this interval remain unanswered, not least that of how, if at all, fossils of the historically enigmatic Ediacaran macrobiota relate to recognisable Cambrian animal phyla. A handful of fossils bearing either a frondose or modular body plan have been described from Cambrian successions, and compared to Ediacaran frondose taxa. The question of whether these are rare ‘survivors’, direct descendants from Ediacaran forms, or entirely unrelated organisms remains unanswered, but has direct implications for evolutionary hypotheses of biotic replacement and mass extinction across the Ediacaran–Cambrian transition. If these organisms are unrelated, their apparent convergent evolution of form raises interesting questions about ecological niche occupancy across this interval.
Project summary : 
This project will examine all previously described examples of Ediacaran ‘survivors’ from global Cambrian successions, including taxa such as Thaumaptilon (from the Burgess Shale), Stromatoveris (from Chengjiang), and un-named specimens from the USA and Australia, to determine their phylogenetic affinities and resolve their relationship, if any, to established Ediacaran and Cambrian taxa. Once the phylogenetic position of these organisms has been constrained, the implications of these findings for evolutionary and ecological convergence amongst early animals will be explored.
What will the student do?: 
After a thorough literature review to familiarise yourself with late Ediacaran and early Cambrian taxa and body plans, you will conduct a detailed morphological study of candidate ‘survivor’ specimens held in museum collections, through a combination of visits to those collections, and specimen loans. You will construct character matrices for these specimens, and conduct phylogenetic analyses to determine the likely relationships between these specimens and documented Ediacaran and Cambrian taxa, and extant animal clades. You will use the resulting information to explore changes in morphospace and ecospace occupation across the Ediacaran–Cambrian transition, and to investigate the implications of your findings for hypotheses of metazoan evolution across this interval. There will be opportunities for fieldwork in the USA and/or South Australia to gather environmental and taphonomic contextual data.
References - references should provide further reading about the project: 
Conway Morris, S. 1993. Ediacaran-like fossils in Cambrian Burgess Shale-type faunas of North America. Palaeontology, vol. 36, pp.593-635.
Jensen, S., Gehling, J.G. & Droser, M.L. 1998. Ediacara-type fossils in Cambrian sediments. Nature, vol. 393, pp.567-569.
Shu, D.G., Conway Morris, S., Han, J., Li, Y., Zhang, X.L., Hua, H., Zhang, Z.F., Liu, J.N., Guo, J.F., Yao, Y. & Yasui, K. 2006. Lower Cambrian vendobionts from China and early diploblast evolution. Science, vol. 312, pp.731-734.
Applying
You can find out about applying for this project on the Department of Earth Sciences page.
Dr Alex Liu
Department of Earth Sciences Graduate Administrator