Deconstructing age estimates for angiosperms.

Estimates of the age of angiosperms from molecular phylogenies vary considerably. As in all estimates of evolutionary timescales from phylogenies, generating these estimates requires assumptions about the rate that molecular sequences are evolving (using clock models) and the time duration of the branches in a phylogeny (using fossil calibrations and branching processes). Often, it is difficult to demonstrate that these assumptions reflect current knowledge of molecular evolution or the fossil record. In this study we re-estimate the age of angiosperms using a minimal set of assumptions, therefore avoiding many of the assumptions inherent to other methods. The age estimates we generate are similar for each of the four datasets analysed, ranging from 130 to 400 Ma, but are far less precise than in previous studies. We demonstrate that this reduction in precision results from making less stringent assumptions about both rate and time, and that the analysed molecular dataset has very little effect on age estimates.