Knowledge of the evolutionary timescale of life is increasing at a rapid pace. The TimeTree database uses a hierarchical system (NCBI's Taxonomy Browser) to identify all published molecular time estimates bearing on the divergence of two taxa (e.g., species). Scientific and common names may be used for searching, and the results include time estimates and their standard errors, numbers of genes, the type of molecular data used (e.g., amino acid or nucleotide), cellular location (e.g., nuclear, mitochondrial, etc.), year of publication, and the PubMed-linked reference. Summary statistics are provided for divergences involving multiple studies and time estimates. Also, all studies and time estimates published by a particular author may be searched. The taxonomic scope, limited in this initial release to tetrapods, will be expanded in the future. The TimeTree Consortium brings together experts of different taxonomic groups for guidance and review of data submitted to the database.

The TimeTree project is jointly directed by Blair Hedges and Sudhir Kumar. Joel Dudley is the Database Expert. Other members of the Hedges and Kumar laboratories who are currently assisting with this project are Angela Graham and Wayne Parkhurst (Multimedia Specialists), and Graziela Valente, Vinod Swarna, and Matthew Heinicke (Data Research and Assembly). During the development phase of TimeTree, we were also assisted by Tina Dennison, Prachi Shaw, and Davide Pisani. We continue to receive helpful feedback from our colleagues in the evolutionary biology community. This project was supported, in part, by grants from the National Science Foundation and the NASA Astrobiology Institute.