The paleontological sites of Toril 3A and B (Upper Aragonian, Biozone C3, MN 7/8) posses an exceptional and abundant fauna of vertebrates. From 1997 until 2001 these two localities have been object of systematic paleontological excavations. Up to now 36 species of large and small mammals have been found in these localities; the association of vertebrates also includes amphibians, reptiles and birds, among the remains of fossils birds it is frequent to found egg shell fragments. There are not significant differences in the qualitative and quantitative faunistic composition of the two sites; in both the undetermined bone fragments and the remains of chelonians, most of them dermal bones, are the dominant fossils. An important characteristic is the abundance of small size hornless ruminants, which are quite scarce in the stratified sites of the Spanish Aragonian. Neither there are differences in the composition of the micromammals, the association is overwhelmingly dominated (more than 95%) for different cricetid species; in Toril 3A beavers reappears for the first time during the Aragonian, and they will be frequent in younger faunas of the same basin. The fossils were deposited in different sedimentary environments, related with alluvial and shallow lacustrine environments.