This will give the age of the most recent common ancestor of a set of taxa, or stretch an input tree, based on available time-calibrated trees. It is still actively in development, so it may break at times. Currently it mostly has mammals in the database, but we are actively adding taxa. See the FAQ page for more info on this project, and the Phylotastic page for more info. This was started at a NESCent hackathon, added to at others, and eventually NSF-funded as part of Phylotastic.
Note source code is available at https://bitbucket.org/bomeara/datelife
We currently use the PhyloOrchard R package to store trees but are transitioning (late 2015) to use OpenTree's tree store. If you want PhyloOrchard, you can install it by doing
DateLife is part of the Phylotastic project, funded by NSF. It uses resources from the Open Tree of Life project, rOpenSci, and TreeBase. To help, please add trees to OpenTree's database! [they can be yours or others']