TimeTreeHD: an App 2.5 billion years in the making

I feel that one of of my weaknesses is a poor memory for facts and figures. Although I tend to learn principles and concepts pretty well, I can easily start to doubt arbitrary pieces of information. This is particularly true when the information itself is subject to change; am I thinking of the new number, or the old one?

One such situation is the age of divergence of different species. As a lecturer of evolutionary biology, this can be a bit embarrassing and awkward. Fortunately, this is not something that I need to worry about (too much) any more, thanks to the TimeTreeHD App for my iPad. Want to know when a cat and a squirrel last shared a common ancestor? (And who wouldn't?!) Simple!


It's 95.2 million years ago (Mya), plus or minus. Probably plus - the "expert opinion" is 97.4Mya. At first, it gives you the mean estimate but down the timeline on the left all the different estimates are marked. The estimates themselves come from all pairwise estimates (in the TimeTree database) featuring species from each side of the tree; cat versus squirrel, for example, includes cow (closer to cat) and mouse (closer to squirrel). Tapping for details allows you to drill down further into different age estimates and see the source publications. Sorted! Well done, TimeTree.Org! (NB. The website might be even better!)