Abstract A new method of environmental inference is presented. This method uses the climatic restriction index (CRI) for each mammal species, based on its geographical range within different climatic regimes, and a set of calculated summary indexes known as the bioclimatic spectrum. Analysis of 50 faunas throughout the world shows that terrestrial mammal communities are effective tools for accurate climatic inference at large spatial scale. The results also indicate that the use of entire mammalian fauna is the best inference system, followed by those based on separate groups such as Insectivora, Rodentia, micromammals and macromammals. Removing Chiroptera from the analysis does not change the results significantly. Bioclimatic analysis appears to be a good method for environmental interpretation. This new method ensures a high qualitative precision. It provides an empirical model for mammal community characterization that must be taken into account for palaeoclimatic reconstructions of continental environments.