Fig. 1

Integration of morphological characters from living and extinct species in a combined analysis with molecular data. The combined matrices contain morphological characters from both fossil (*) and living species, but no molecular data from fossil species. Red branch lengths are created due to the inclusion of extinct taxa and are estimated using non-molecular data. Intuitively, we expect t₃, t₄, and t₇ to be estimated well if the non-molecular data has a strong time structure. The inclusion of non-molecular data will only benefit if the time structure is concordant between molecular and non-molecular datasets. However, we emphasize the importance of using morphological data to infer the phylogenetic position of extinct taxa in the tree to determine which internal nodes are to be calibrated