Overall, the results of this study – particularly our reconstruction of Ateles marginatus as basal within the Ateles radiation and the older divergence dates we calculated for most species-level splits in the phylogeny – were somewhat unexpected and challenge previous ideas about the evolutionary history of spider monkeys. For the future, of course, it will be important to add additional loci besides just mtDNA to the dataset. Additionally, adding sequence data from more samples of A. marginatus as well as samples from additional populations of other species of spider monkeys would improve our understanding of genetic diversity within each species as well shed light on possible hybridization between species in areas suggested by Froehlich et al. (1991).