This evolution consists, first in the elaboration of the underground net systems, then in a long polyphased process of filling – emptying the karstic voids, according to the up and down base level changes that occurred almost continuously during the first half of the Tertiary era. The filling sediments are mostly vadose clay deposits, the various ages of which being established from the study of their fossil vertebrate contents (for latest accounts see Pélissié & Sigé 2006). Then, since latest Oligocene times, the Quercy platform was covered with prograding lacustrine sediments of the Aquitaine Basin. Finally, the whole structure was strongly worn down by the so- called Plio-Pleistocene erosional phase: the previously deep underground system became closer to the surface, and was exposed both to erosion and widening, but also Plio-Pleistocene fillings occurred as shown by the fossils they include (Crochet et al. 2006). Among the latter are rare Late Pliocene and Plio-Pleistocene tooth specimens.