“TimeTree is a public knowledge-base for information on the evolutionary timescale of life. A search utility allows exploration of the thousands of divergence times among organisms in the published literature. A tree-based (hierarchical) system is used to identify all published molecular time estimates bearing on the divergence of two chosen taxa, such as species, compute summary statistics, and present the results. Names of two taxa to be compared are entered in the search window and the results are presented on a separate page. Alternatively the last name of an author is entered to find divergence times published by that person. For those interested in published summaries of relationships and divergence times of major groups of organisms (family level and above), see the authoritative synthesis The Timetree of Life. Those most likely to find the search utility in TimeTree useful will be researchers who already have some knowledge of evolutionary biology and wish to mine the available published data, which often require interpretation. For example, the taxonomy hierarchy used in TimeTree is NCBIs Taxonomy Browser with only limited adjustments (corrections) at present. For the vast majority of comparisons this will be adequate and not create errors. However, for some highly controversial parts of the Tree of Life (e.g., relationships of the families of lizards and snakes) NCBIs Taxonomy Browser tree may be incorrect, creating problems for corresponding time estimates. Future plans for TimeTree include a taxonomy tree that is more up-to-date and user-editable. For reviews of the history and methods of time estimation, and other useful information, see RESOURCES. TimeTree is jointly directed by Blair Hedges (Pennsylvania State University) and Sudhir Kumar (Arizona State University).”