The big cats of the fossil site Château Breccia Northern Section (Saône-et-Loire, Burgundy, France): stratigraphy, palaeoenvironment, ethology and biochronological dating

International audienceThe Château site, known since 1863, was rediscovered in 1968 and new excavations were carried out there between 1997 and 2006. Bear remains largely dominated the Château Breccia fossil assemblage, but the characteristic peculiarity of this site was the abundance of big cats. The old karstic system, including the Château Breccia fossil site, has been completely destroyed, primarily by erosion, but later by quarrying. During the Pleistocene the cave served as hibernation dens for bears. This was most likely also the birthplace for bear cubs. These bear cubs, whether alive or dead, could be a significant source of food for big cats during the winter. The stratigraphy of the infill (Northern Section) reveals successive phases of occupation. The two main fossiliferous layers were labelled Breccia 4 (Br. 4) and Breccia 2 (Br. 2), the former being the earliest. In both cases, we noticed different, though equivalent, animal associations: a bear (Ursus deningeri), a big cat (Panthera gombaszoegensis, Panthera spelaea fossilis), a canid (Canis lupus mosbachensis), and constantly Arvicola cantianus (= A. mosbachensis). Palynological analysis indicates a milieu of moderately cold temperatures for the two breccias. It suggests an open landscape with grassy areas and a forest of pine, fir, oak and other broadleaved trees. Thus far, all attempts to obtain absolute dates for the Northern Section of the site have been unsuccessful: 14 C and thermoluminescence cannot be used, U/Th and Uranium series dating has failed up to now and ESR is not possible because of the absence of herbivore molars with thick enamel. Therefore, only Ursus deningeri, Panthera gombaszoegensis, Panthera spelaea fossilis, lagomorphs and microfauna with Arvicola cantianus biochronologies allow us to suggest an early Middle Pleistocene age for Breccia 4 and a mid Middle Pleistocene age for Breccia 2. The Château Breccia stratigraphy permits biochronologic dating but also the reliable reconstruction of the evolution of two big cats. Panthera gombaszoegensis is found in the Breccia 4 sediments, the oldest from the site. P. spelaea fossilis and P. gombaszoegensis probably coexisted in Breccia 3. Breccia 2 contains only P. spelaea fossilis, which conforms exactly to what is known about its first appearance in Europe