Fig. 1
From: Fast algorithms for computing phylogenetic divergence time
Divergence Time of the Ground Squirrels. The annotations on each branch refer to the length of the branch calibrated to millions of years. For example, the node marked with a star shows that the prairie dogs diverged from the groundhog/golden squirrel linage 5.92 million years ago. Geological era’s are shown to allow for correlation of species divergence to geological events