The introduction of European domestic fauna in the process of Spanish conquest represented a major change in the cultural use of animals, with influence on the kind of acquisition and processing. Although this item has been recognized, in fact has been poorly documented. The initial hypothesis of this paper assume that the introduction of domestic animals induce a reduction in faunal diversity on human settlements. To measure these changes were used numerical approaches, such as index of Shannon and Taxonomic Distinctness, either Seriation, which facilitated the search of patterns. Those analyzes were applied in two sites located in the Basin of México with evidences of both prehispanic and post conquest settlements, both were studied previously and the excavation units allow a detailed and differential analysis of the faunal findings. The results of both sites suggest a faunal use pattern, were the most radical change was the introduction of European domestic fauna, mainly cattle, sheep and, to a lesser extent, poultry; while persistence, representing local resources, was the use of wild turkey and, to a lesser extent, of some fish and waterfowl. It was observed a tendency to a lower faunal diversity at post-conquest sites. Those elements allow us to suggest a differential impact on the introduction of European domestic fauna and also a time period where it was used both introduced and local fauna, but finally the former predominate. [ABSTRACT FROM AUTHOR]