TY - JOUR TI - A Bayesian approach to dynamic homology of morphological characters and the ancestral phenotype of jawed vertebrates AU - King, Benedict AU - Rücklin, Martin A2 - Zhu, Min A2 - Perry, George H A2 - Zhu, Min A2 - Ahlberg, Per E VL - 9 PY - 2020 DA - 2020/12/04 SP - e62374 C1 - eLife 2020;9:e62374 DO - 10.7554/eLife.62374 UR - https://doi.org/10.7554/eLife.62374 AB - Phylogenetic analysis of morphological data proceeds from a fixed set of primary homology statements, the character-by-taxon matrix. However, there are cases where multiple conflicting homology statements can be justified from comparative anatomy. The upper jaw bones of placoderms have traditionally been considered homologous to the palatal vomer-dermopalatine series of osteichthyans. The discovery of ‘maxillate’ placoderms led to the alternative hypothesis that ‘core’ placoderm jaw bones are premaxillae and maxillae lacking external (facial) laminae. We introduce a BEAST2 package for simultaneous inference of homology and phylogeny, and find strong evidence for the latter hypothesis. Phenetic analysis of reconstructed ancestors suggests that maxillate placoderms are the most plesiomorphic known gnathostomes, and the shared cranial architecture of arthrodire placoderms, maxillate placoderms and osteichthyans is inherited. We suggest that the gnathostome ancestor possessed maxillae and premaxillae with facial and palatal laminae, and that these bones underwent divergent evolutionary trajectories in placoderms and osteichthyans. KW - placoderm KW - homology KW - jaws KW - phylogeny KW - vertebrate KW - morphology JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -