This comprehensive overview of the behavioural and ecological diversity of the colobines shows that we have greatly expanded our understanding of the taxonomy, phylogeny, morphology, natural history, behaviour and conservation status of this subfamily since Glyn Davies and John Oates (1994) published the first book on them. Nonetheless, there remain many gaps in our knowledge. In Chapter 2, Roos highlights that our current understanding of the taxonomy of colobines should be considered preliminary because classifications are still largely based on phenotypic differences between museum specimens. Changes will likely need to be implemented as data become available on ecology, behaviour, morphology and especially genetics of many species and subspecies. Roos also notes that relative to the cercopithecines, colobines are neglected in study effort and thus new findings have the potential to expand our understanding of their taxonomic diversity, especially in genera such as Piliocolobus, Colobus, Presbytis, Trachypithecus and Semnopithecus that are found over large geographic areas and are species-rich.