The role of the Eastern Mountains of the Iberian Central System (EMICS) as both a barrier to the dispersion of, and ecologic refuge for, Scarabaeoidea dung beetles is studied. An Ecogeographic Patterns comparison method (EP = set of ecologic features common to, and present geographic range shared by, a group of species) to weight the historical and ecological causes of geographic distribution is proposed. This method is based on the assumption that species now sharing geographic ranges, with common structural and nonstructural features, also have a (to some extent) common evolutionary history. The data studied indicate that (i) fauna of the N and S slopes are identical. Euroturanian and Mediterranean species, and those which belong to the Scarabaeidae family, predominated in all samples. Except for very few species, the EMICS have not impeded dispersal of Scarabaeoidea dung beetles; minor regional differences should be explained in terms of ecological causes. (ii) The variation in abundance,