A can of worms-tracing the origins of Ecdysozoa using fossils, molecules and morphology in a Bayesian framework

Ecdysozoans comprise some of the most successful invertebrate phyla, such as the arthropods and nematodes. However, other members of the group are less abundant today than they used to be. An amazing fossil record with a focus on newly collected material from the Early Cambrian Sirius Passet may provide means to better understand the nature of the ancestral ecdysozoan and how these many different fossil worms are related to their extant counterparts. It has been debated whether many of these vermiform fossils are subtending various branches of the tree or mainly the group that they resemble the most, the priapulids. This project will seek to integrate fossils, morphology and molecular sequence data to investigate the phylogeny and evolution of the Ecdysozoa. Many new fossils have been discovered in the remote Sirius Passet in North Greenland. These new fossils feature unseen characters that may be useful in better understanding the nature of palaeoscolecid worms and their affiliation to living groups. Using these fossils as a template, we will explore the fossil record from different sites and compile their anatomy with modern forms to explore their phylogenetic placement. Furthermore, we will explore the use of combined morphology, molecules and fossils with stratigraphic ages to co-estimate phylogeny and divergence times which may help reveal incidences of convergent evolution that can result in erroneous placements of fossil taxa. Within the framework of thinking about Ecdysozoan evolution there are several levels of freedom within the student can explore different subject and take the project in new directions. These can range from exploration and description of new taxa, developing methods for visualization and reconstruction of fossils, development of phylogenetic methods or testing methods on other groups of organisms to compare and contrast with. A student with a personal perspective on how the project could evolve and develop is much welcomed.