The rise of the animals was a profound transition in the History of Life; for the first-time organisms were able to engineer the environment around them, altering geochemical cycles, building complex ecosystems and diversifying into myriad forms. However, the rise of the animals is also one of the most controversial episodes in Earth History. Most major animal groups appear in the fossil record during a major evolutionary radiation event between ~520 and 550 million years ago known as the Cambrian Explosion when the blueprints for the animal phyla (arthropods, vertebrates, cnidarians) were laid down and, remarkably, have remained more-or-less unchanged in the half a billion years since. My research is focused on the Period of time just before the Cambrian Explosion – the Ediacaran Period, and the Ediacaran-Cambrian transition.

While fossil representatives of the living animal phyla diversify in the Cambrian Period, the timing and nature of their earliest antecedents remains controversial. Fossil assemblages from the late Ediacaran Period preserve the remains of fossil organisms with long-extinct bodyplans, historically excluded from analyses of the early evolution of animals because of extreme uncertainty regarding their phylogenetic placement. My novel approach to the study of these organisms has been to investigate their growth and development across whole populations of taxa with non analogue frond-like bodyplans.

My work has revealed new developmental characters that can be used to rigorously constrain the phylogenetic position of these fossils. In this talk, I will introduce my work on the fossils of the Ediacaran Period and set out the case for an animal affinity, before discussing the demise of this unique way of building a body which, fossils from the Northwest Highlands, suggest was much later than previously thought.

Bio: Frankie Dunn is a palaeobiologist based at the University of Oxford. She received her undergraduate degree from the University of Warwick in 2015 and her PhD in 2019 from the University of Bristol, which focused on the Ediacaran Macrobiota – a strange group of organisms sometimes invoked as ancient animals but displaying non-analogue bodyplans. She subsequently moved to Oxford and after a number of early career fellowships is now a NERC Independent research fellow and a Senior Researcher at the Oxford University Museum of Natural History. Frankie’s research focuses on the origin and early evolution of animals and particularly on the fossil record of the late Ediacaran Period (approximately 570 – 540 million years ago). The aim of this research is to understand how animal bodyplans evolved in deep time.

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