VETULICOLIANS, CONODONTS, AND JAWLESS FISHES: RESOLVING THE INTERRELATIONSHIPS OF EARLY DEUTEROSTOMES USING BAYESIAN TIP-DATED PHYLOGENETICS

The phylogenetic position of vetulicolians within deuterostomes and conodonts within chordates has been controversial since these affinities were first proposed. No study has addressed these questions within a deuterostome framework, based on multiple OTUs (Operational Taxonomic Units) per taxon including representatives of all early chordate/hemichordate classes. We performed such an analysis using both maximum parsimony and Bayesian tip-dated phylogenetic inference. We fitted morphological characters of fossil taxa to a molecular scaffold of extant interrelationships under deuterostome monophyly and the recent proposal of deuterostome paraphyly. The results help to clarify the affinities of these problematic groups, and shed light on the ancestral condition of early chordates, deuterostomes, and bilaterians.