One theory had suggested the rise of the mammals was directly linked to the disappearance of the dinosaurs. The evidence challenging the connection comes from 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.

As Kate Jones, a co-author of the project explained: "The supertree is a new way of showing all the mammal species on the planet, starting with a common ancestor. Species relationships can be inferred from morphological characteristics and genetic sequences". And she continues by saying: "If we had done this from scratch, we would have had to get molecular and morphological data for 4,000 different species. (...) What we did instead was use already published information from hundreds of researchers around the world. We used a new technique called supertree construction which allows us to get all the information that's out there, re-code it and re-analyse it as if it's all part of one dataset."