This has the core functionality of DateLife, part of Phylotastic (NSF-funded). It is still under rapid development. With this package, you can get ages of clades or even chronograms using information in OpenTree's tree store. Newick strings or phylo objects can also be dated using these trees and the congruifier, part of Geiger (Eastman et al. 2013, Harmon et al. 2008).
For now, requires github version of rotl:
Then install datelife: