Abstract
The origin of animals is one of the most profound events in the history of Earth, but our understanding of how and when animals diversified is patchy. While the Cambrian fossil record reveals that the overwhelming majority of animal bodyplans (i.e. the animal phyla) had been established by at least 520 million years ago, fossils from the late Ediacaran reveal assemblages of early animals with distinctive forms that have no counterparts among living species. This has meant that, despite holding crucial insights into some of the earliest phases of animal evolution, these fossils have, for the most part, been excluded from the debate. Among Ediacaran macrofossils, the rangeomorphs are amongst the most ancient, and therefore understanding their plesiomorphic condition may offer key insights for understanding the ancestral state of total-group Eumetazoa, the animal group to which they belong. The rangeomorphs record primary data on the evolution of tissue-grade animals before the origin of a gut; there are no living tissue-grade animals which are primarily gutless and so they represent an untapped resource for reconstructing this early and important stage in animal evolution. In this talk, I will introduce a new rangeomorph which allows us to polarise the rangeomorph tree of life and suggests that rangeomorphs evolved from a reclining, colony-like stoloniferous ancestor before incorporating other Ediacaran macrofossils into this pan-animal phylogenetic framework. Significantly, I recover the Ediacaran macrobiota as paraphyletic: rather than the unique Ediacaran bodyplan being a dead end, the modular anatomy these fossils exhibit was ancestral for much of the diversity of living animal life.
About Dr Frances Dunn
Frankie is an early career research fellow supported by the Royal Commission for the Exhibition of 1851 and Merton College, where she holds a Junior Research Fellowship. Her research interest focuses on understanding the origin and early evolution of animals. More specifically, she focuses on the Ediacaran Macrobiota, a group that may represent some of the earliest records of animal life. She is also interested in how the fossil record informs our views of these early events.
More information
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