DEEP ORIGINS OF EXTANT BRYOZOAN CLADES: EVIDENCE USING A NEW, FOSSIL-CALIBRATED MOLECULAR PHYLOGENY

The fossil record of bryozoans is long and rich, starting in the Ordovician. It is amenable to integrated analyses with phylogenetic hypotheses generated using molecular sequence data from extant bryozoans. Yet, molecular phylogenetic studies of bryozoans are still rare. In this presentation, we present inferred topological relationships among c. 400 genera of extant cheilostome bryozoans, the most species-rich order of extant bryozoans today, together with a number of bryozoan and non-bryozoan outgroups, using newly generated-genome-skimmed data from 15 high copy mitochondrial and two nuclear (rRNA) genes. Using this inferred topology, we employ 19 fossil calibrations and a relaxed clock model implemented in MCMCTREE to estimate the node ages of key bryozoan clades. We find that cheilostome bryozoans have an origin that might be 200 million years earlier than its first definitive fossil record in the late Jurassic. We discuss the plausibility of this result in concert with other inferred node ages in the context of our taxon and gene sampling.