Divergence time estimates using Penalized Likelihood. Mean age chronogram showing 95% confidence intervals of age nodes (bars), based on 1000 Bayesian trees from a post burn-in tree sample. The stars represent calibration points: C1, crown age of Asterales as estimated by Bremer et al. , fixed age = 93 Ma; C2, crown age of subfamily Campanuloideae, based on a fossil Campanula, minimal age = 5.33 Ma ; C3 -- C7, diversification of Hawaiian taxa, corresponding to the age of the oldest island of the Hawaiian Ridge (Kure) after which a continuous chain of islands has been available as 'stepping stones' for propagules of the Hawaiian biota, maximum age = 29.8 Ma .
Antonelli BMC Biology 2009 7:82 doi:10.1186/1741-7007-7-82