The study of vicariance events is a key issue in evolutionary biology. Numerous articles have been written on the importance of vicariance versus dispersal. Usually, molecular trees are calibrated using estimates on the timing of continental break-up provided by geologists. Van Boxclaer and co-authors now reverse this argumentation by using a molecular time tree to date not exactly the break-up of Gondwana land but rather the time when over land dispersal was still possible. To this end, they have performed a large scale phylogenetic analysis of two world-wide distributed groups of frogs. Frogs are an ideal choice for such analyses as almost all species are highly intolerant to salt water and hardly any example exists for oceanic dispersal of frogs. Using long DNA sequences and several calibration points they are not only able to resolve the phylogenetic tree with high support, they are also able to date the divergence between many continental groups, e.g. Africa vs. South America or India vs. Australia. In fact due to the choice of species’ they are able to date divergence events between all southern regions which resulted from the break-up of Gondwana land, and the estimates support the notion that over land – or very short oceanic distances – dispersal was possible much longer than estimated to date. This work shows beautiful, how a reversal of the normal order of arguments can lead to new insights and revise long accepted views. It also shows the power of large scale phylogenetic analyses for investigating events far back in time and the importance of knowledge about the biology of the organisms studied. Without the careful choice of a salt-intolerable species group, the arguments would be much less powerful. Certainly, there are some caveats in such analyses. First, they depend heavily on the choice of calibration points – even though this problem can be, as done in this work, ameliorated using several calibration points. Second, frogs represent only one of many species groups and other species may give other dates. Thus, it would be great to have some more analyses using other species groups – which faces the problem that they would need to be as salt intolerable as frogs. Overall, the analysis presented by Van Boxclaer and co-authors no doubt is a welcome and carefully performed contribution to the discussion about vicariance. Hopefully, more such analyses that combine knowledge about a species’ biology with a thoughtful reversal of the common order of argument will be performed in the future as they have the potential to shed new light on many issues believed to represent accepted facts.