Figure S4 from Probabilistic divergence time estimation without branch lengths: dating the origins of dinosaurs, avian flight and crown birds G. T. Lloyd D. W. Bapst M. Friedman K. E. Davis 10.6084/m9.figshare.4154250.v1 https://rs.figshare.com/articles/journal_contribution/Figure_S4_from_Probabilistic_divergence_time_estimation_without_branch_lengths_dating_the_origins_of_dinosaurs_avian_flight_and_crown_birds/4154250 Figure to demonstrate that the node-dating algorithm of Hedman is not generalisable to a tree-dating algorithm. Outgroup sequences for three nodes (X-Z) on a hypothetical phylogenetic tree of six fossil taxa (A-F) with sampled ages (T1-T6). Note that for the standard (non-conservative) Hedman approach taxon C is re-dated as T5, the same age as the oldest member (B) of its sister clade (AB), biasing the date of node Y towards a minimum possible age (invalidating the standard approach). Whereas under the conservative Hedman approach taxon C is ignored, as it is younger (T6) than the lower bound for Y set by node AB (T5). Under the conservative scenario the sequence of outgroup taxa for nodes X and Y are identical, meaning branch XY would have zero-length (invalidating the conservative approach). Due to these problems in the present paper only nodes X and Z are considered dateable using the Hedman algorithm (conservative approach), whereas node Y would be dated by making random draws from a uniform distribution bounded by separate random draws from the posterior distributions of nodes X and Z. 2016-11-01 11:00:23 birds dinosaurs divergence time phylogeny