Total-evidence dating and the phylogenetic affinities of early fossil passerines

Passeriformes is the most diverse and globally widespread order of living birds. However, little work has been done on the phylogenetic relationships within their fossil record. Recent advances in total-evidence phylogenetic methods have improved topological and age estimation by using morphological, molecular and temporal data. This provides the opportunity to investigate the phylogenetic affinities of five recently described passerines from the early Oligocene of Europe, including some of the most complete and oldest passerine fossils described to date. We compare maximum parsimony, non-clock Bayesian inference, and total-evidence tip-dating Bayesian analysis to estimate relationships and divergence times of the fossil passerines. We find <i>Wieslochia weissi</i>, <i>Crosnoornis nargizia</i> and NT-LBR-0014 form a clade within Tyranni (suboscines) either in the stem or within Old-World suboscines (Eurylaimides). <i>Jamna szybiaki</i> is recovered as the sister lineage of crown Passeriformes. We confirmed the oscine affinities of <i>Resoviaornis jamrozi</i>. Its precise position within Passeri remains ambiguous, but affinities within Corvides or Passerides may be more likely considering the biogeographic history of the group. We emphasize the importance of an informative tree age prior in total-evidence dating analyses and appeal for the further development of models for phylogenetic inference using morphology.