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They let scientists trace the evolution of groups of species and map the relationships among organisms. With the growth of molecular analytic techniques, the construction and study of supertrees has required ever-greater computing power, as well as contributions from an increasingly diverse group of scientists.

The group publishing in Nature includes bioinformaticians, who gathered and analysed the data needed to construct the mammalian supertree, as well as palaeontologists and ecologists, who helped put the information into context.

"The big question now is what took the ancestors of modern mammals so long to diversify," said MacPhee. "It's as though they came to the party after the dinosaurs left, but just hung around while all their distant relatives were having a good time. Evidently we know very little about the macroecological mechanisms that play out after mass extinctions."

In collaboration with other researchers around the world, the team is now using the supertree to answer a whole range of questions about the evolution of mammals.

"The supertree itself is really just the first stage," says Mr Beck. "The information it provides allows us to look at the overall pattern of mammalian evolution in far greater detail than before. It has applications in ecology, conservation, physiology, palaeontology, amongst other fields, and it will also shed new light on the evolution of our own species - it's a big step forward."