Unifying fossils and phylogenies for comparative analyses of diversification and trait evolution

1. The aim of macroevolutionary research is to understand pattern and process in phenotypic evolution and lineage diversification at and above the species level. Historically, this kind of research has been tackled separately by palaeontologists, using the fossil record, and by evolutionary biologists, using phylogenetic comparative methods. 2. Although both approaches have strengths, researchers gain most power to understand macroevolution when data from living and fossil species are analysed together in a phylogenetic framework. This merger sets up a series of challenges - for many fossil clades, well-resolved phylogenies based on morphological data are not available, while placing fossils into phylogenies of extant taxa and determining their branching times is equally challenging. Once methods for building such trees are available, modelling phenotypic and lineage diversification using combined data presents its own set of challenges. 3. The five papers in this Special Feature tackle a disparate range of topics in macroevolutionary research, from time calibration of trees to modelling phenotypic evolution. All are united, however, in implementing novel phylogenetic approaches to understand macroevolutionary pattern and process in or using the fossil record. This Special Feature highlights the benefits that may be reaped by integrating data from living and extinct species and, we hope, will spur further integrative work by empiricists and theoreticians from both sides of the macroevolutionary divide.