Interpreting fossils of fly-speck fungi using comparative anatomy and phylogenetics

Critical interpretations of fossil fungi combined with phylogenies of living species have the potential to reveal patterns of character evolution and to inform estimates of the geological timing of fungal radiations. Some of the best fungal fossils are of thyriothecia, formed by fly-speck fungi. A thyriothecium is a minute fungal sporulating structure, with a flat scutellum and a shield-like upper surface. Scutella have distinctive cell patterns that are formed by a sequence of hyphal branching and septation. However, for thyriothecial species, phylogenies from DNA sequence data and illustrations of scutella remain have been limited. In Chapter 2, I present a comprehensive phylogeny of thyriothecial Dothideomycetes based on 4251 nucelotides for 320 taxa, contributing new nuclear rDNA sequence data for 14 thyriothecial fungi. I code character states for taxa including 60 thyriothecial species and then estimate ancestral character states using the Bayesian posterior distribution of topologies from my dataset to account for phylogenetic uncertainty. Radiate thyriothecia are only found in Class Dothideomycetes, where they seem to have evolved independently at least three times. In Chapters 3, 4 and 5, I describe new species of Cretaceous scutellum fossils. Scutella can be abundant on fossilized leaf cuticles and are well documented in deposits of Eocene age and younger (