PhD: Landscapes of Extinction and Evolution: The Global Sedimentary Record of Biotic-Abiotic Feedbacks in Mesozoic and Cenozoic River Systems

Amongst many abiotic-biotic feedbacks observable in modern environments, one crucial role is that which plants play in moderating processes and landforms in rivers. Studies into such modern interactions commonly cite a geological observation that ancient rivers left a fundamentally different sedimentary record prior to the evolution of land plants. However, Earth's oldest vegetation was dominated by extinct lineages, with physiological traits and environmental effects that may not fully be analogous to modern flora. The geological record of post-Palaeozoic vegetation controls is poorly understood, but this 250-Ma interval has seen a number of extinctions (e.g., the collapse of lyscopsid-dominated rainforests) and evolutionary events (e.g., the evolution of angiosperms and C4 grasslands) that should be expected to have resulted in shifts in the global ‘behaviour' and sedimentary products of ancient rivers. This research will quantify the sedimentary record during this prolonged and punctuated floral transition: with implications for the underlying role of plants in river processes and the physical-ecological impacts expected when vegetation is modified/removed from modern rivers.