Out from the shadow of the dinosaurs? Dietary diversity and niche partitioning in Cretaceous and Palaeocene mammals

This project will use new techniques to address one of the perennial questions in palaeontology: the impact of dinosaurs and their extinction on mammal evolutionary history. A number of recent studies have focussed on the timing of mammal diversification (e.g. Wilson et al. 2012, Close et al. 2015), but whether mammal diversity was supressed during the ‘reign’ of dinosaurs and released only after their demise is a question of more than just numbers of species – it’s a question of ecological diversity. Morphological analysis of well-preserved articulated mammal skeletons of Jurassic age is starting to paint a picture of mammals occupying a broader range of ecological niches than previously thought, but the majority of fossil mammals are known only from disarticulated remains and teeth, and are not amenable to this type of functional analysis. Consequently, the degree to which their ecological diversity was affected by the K-Pg extinction, and the pattern of ecological diversification during the Palaeocene, have been difficult issues to address.
This project will employ a new approach: textural analysis of tooth microwear. The application of this approach to early mammals was recently pioneered by the supervisors (Purnell et al. 2013, Gill et al. 2014). You will combine this with isotopic data and mesowear analysis of teeth, in phylogenetic context, to conduct the first such multidisciplinary investigation of the dietary diversity of mammals before and after the extinction, and of the subsequent patterns of trophic niche occupation and partitioning. You will establish the dietary guilds to which the early members of modern mammal lineages belong. Recently, this type of textural analysis of microwear has revealed hidden trophic diversity in Jurassic mammals, indicating that lineage splitting during the earliest stages of mammalian evolution was associated with ecomorphological specialization and niche partitioning (Gill et al. 2014). This project, applying the approach to Cretaceous and Palaeocene fossils, will similarly yield new insights into the evolutionary history of mammals.