Abstract: Palaeontologists have always had something to say about the origins of biodiversity. However, until recently, most of what they had to say was somewhat speculative. Following the inspirational suggestions by Simpson in the 1940s, the American ‘paleobiological revolution’ of the 1970s encouraged palaeontologists to think numerically and in terms of hypothesis testing. What was lacking from that revolution was phylogeny, and this provides the basis of informative analyses that truly link deep time fossil data with molecular trees and extant taxa.