Phylogenies and distributions of extant species are often used to test competing historical biogeographic scenarios and elucidate diversification processes. As such, inferences are only as good as the robustness of the trees and the accuracy of the ranges. What is more, both datasets are inherently problematic because of their temporal variability: phylogenies based on sequence data must account for coalescent processes and thoroughness of sampling, while biogeographic ranges are dynamic with range expansions via dispersal and contractions leading to relictualism and ultimately extinction. When interpreting historical events from present perspectives, we must be certain to check assumptions, accommodate this variation, and have a clear understanding of null hypotheses. Should we expect sister pairs to behave equally on the same evolutionary stage if they have equivalent attributes? How much can variability affect resulting patterns? Given a well-supported phylogeny and good range data, how many alternative biogeographic scenarios are possible? Are probable? How do we take account of the coalescent process in polarizing biogeographic events? Are conclusions vulnerable based on incomplete sampling? What additional information can increase confidence in explanations? I will address each of these points using data from various molluscan groups including cowries, cones, limpets, and turbinids.