PhD: The origin and radiation of arthropods

The origin and diversification of arthropods is a major evolutionary event. It encompasses the construction of unique body plans of the major constituent clades, the pancrustaceans, chelicerates and myriapods. Furthermore, it occurs at a time of massive innovation of animal clades: the Cambrian explosion. The fossil record is fundamental to interpretations of these events. It allows us to reconstruct the sequence of morphological changes, and to reconstruct the timing of those events using the ages of fossil taxa. This is only possible with a robust evolutionary tree, but the phylogeny for this episode is far from stable. Ambiguity persists not only over the affinity of individual taxa, but also with respect to the relationships between major constituent clades. Furthermore, solutions look very different when derived using different phylogenetic methods (parsimony with implied weighting or Bayesian analyses). This project will directly tackle these challenges by developing new ways of working with morphological phylogenies. Comparisons between molecular and morphological datasets from modern groups of arthropods will be used to inform interpretations of fossil morphology through identification not only of the aspects of morphology that yield congruent results, but also the techniques that yield stable trees. Furthermore, integration of molecular, morphological and fossil data will provide a time-scaled phylogeny to test hypotheses about the rates and sequences of evolutionary events.