Overview

Project Highlights:

  • Use new techniques to shed fresh light on a long-standing evolutionary question – the diversity of mammals after the extinction of dinosaurs
  • Acquire a suite of skills for quantitative statistical analysis of textures, morphology and evolutionary patterns
  • Opportunities to travel to collect data from fossil collections across Europe and the US, and conduct fieldwork in New Mexico

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 other dietary proxies (isotopic data, mesowear and shape analysis of teeth) in phylogenetic context, to conduct the first multidisciplinary, multiproxy 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. 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.

This project is ideal for applicants with a first degree in geological or biological sciences and an aptitude for quantitative analysis. At Leicester you will join a dynamic group of researchers, PhD and Masters students working on novel analyses of diet and trophic niche in fossil vertebrates.

Analysis of tooth microwear texture in early mammals provides new evidence of dietary specialization. The method reveals previously hidden trophic diversity (DEM inset from Gill et al. 2014).

Methodology

The project will focus on material from the San Juan Basin of New Mexico – one of the world’s premier localities for Palaeocene mammal fossils. The collections, held in the New Mexico Museum of Natural History, include new material recently excavated by the supervisors, and the project offers opportunities for fieldwork in New Mexico. Dietary analysis will employ quantitative 3D texture analysis of microwear using methods developed at Leicester (Purnell et al. 2013, Gill et al. 2014). Combining this with mesowear analysis, isotopic data, functional morphological analysis, and quantitative phylogenetic methods will allow robust analysis and hypothesis testing of the role of feeding and diet at different temporal and spatial scales. This approach will allow independent testing of dietary hypotheses, and evaluation of specific roles within broader dietary guilds, and has the potential to pick up dietary transtions that predate and potentially drive morphological adaptation of teeth to new functional roles.

Training and Skills

CENTA students benefit from 45 days training throughout their PhD including a 10 day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to the student's projects and themes.  Specialist training will include tooth microwear analysis, techniques for phylogenetic testing and analysis of macroevolutionary patterns, and anatomical analysis of Cretaceous-Paleogene mammals. The emphasis will be on robust quantitative analysis and statistical hypothesis testing.

Timeline

Year 1: basic research skills training; familiarisation with literature, existing datasets and tooth microwear techniques. Collection and analysis of tooth microwear data in extant comparator taxa following visits to collections in UK, Europe. Possible fieldwork in New Mexico.

Year 2: Complete collection and analysis of tooth microwear in fossil mammals following visits to collections, particularly in USA. Mesowear and functional morphological analysis, and integration of isotopic data.

Year 3: Synthesis of results and analysis of diet in phylogenetic and macroevolutionary context. Writing the thesis will take place during the final year, but papers will be published throughout the project. There will also be opportunties to give presentations at international meetings in the UK and overseas.

Partners and collaboration (including CASE)

Prof. Mark Purnell leads research on quantitative tooth microwear at Leicester and has developed new applications of the techniques to a variety of vertebrates, including small insectivores and primitive mammals. Dr Stephen Brusatte has published widely on fossil mammals and dinosaurs, and has extensive experience in the application of phylogenetic inferences and quantitative approaches to analysis of palaeontological data. Dr Thomas Williamson is an expert on Cretaceous and Palaeocene vertebrates, particularly from the San Juan Basin of New Mexico.

Further Details

Any questions? Contact Mark Purnell, University of Leicester, mark.purnell@le.ac.uk

http://www.le.ac.uk/people/map2