the most complete family tree compiled for mammals. It shows how different groups, such as primates and rodents, are related and when they diverged. An international team compiled the mammal "supertree" from existing fossil data and from genetic analyses.
Under this model, placental mammals split into major sub-groupings, which originated and rapidly diversified after the mass extinction event - thought to have been caused by an asteroid or comet striking Earth 65 million years ago (a point in time recorded in rocks and referred to by geologists as the K-T boundary).
clipped from: www.visualcomplexity.com 
