Strong morphological support for the molecular evolutionary tree of placental mammals.

The emerging molecular evolutionary tree for placental mammals differs greatly from morphological trees, leading to repeated suggestions that morphology is uninformative at this level. This view is here refuted empirically, using an extensive morphological and molecular dataset totalling 17 431 characters. When analysed alone, morphology indeed is highly misleading, contradicting nearly every clade in the preferred tree (obtained from the molecular or the combined data). Widespread homoplasy overrides historical signal. However, when added to the molecular data, morphology surprisingly increases support for most clades in the preferred tree. The homoplasy in the morphology is incongruent with all aspects of the molecular signal, while the historical signal in the morphology is congruent with (and amplifies) the historical signal in the molecular data. Thus, morphology remains relevant in the genomic age, providing vital independent corroboration of the molecular tree of mammals.