Valbro : un nouveau site à vertébrés de l'Oligocène inférieur (MP22) de France (Quercy). I - Contexte géologique ; Mammalia : Rodentia, Hyaenodontida, Carnivora

The locality Valbro (Quercy, France) has yielded a rich fossil vertebrate fauna. Here are presented the geological context, a preliminary faunal list and the systematics of the Rodentia and carnivores, the most abundant taxa of the fauna. The Rodentia are known from 11 taxa: the Theridomyidae Blainvillimys gregarius Schlosser, 1884, Blainvillimys ?gemellus Vianey-Liaud, 1989, Issiodoromys medius (Vianey-Liaud, 1976) and S. cayluxi Schlosser, 1884, the Aplodontidae Plesispermophilus angustidens Filhol, 1882, the Gliridae Butseloglis tenuis (Bahlo, 1975), Butseloglis micio (Misonne, 1957) and Bransatoglis planus (Bahlo, 1975), the Sciuridae Palaeosciurus goti Vianey-Liaud, 1974 and cf. Oligopetes sp., and the Cricetidae Atavocricetodon sp. aff. A. nanus (Pelaez-Campomanes, 1995). Thirteen taxa of carnivores are present at Valbro; among the Hyaenodontida: Hyaenodon leptorhynchus Laizer et Parieu, 1838 and cf. Apterodon sp.; among the Carnivora: a Feliformia gen. et sp. indet., the Nimravidae Nimravus intermedius (Filhol, 1872), Dinailurictis bonali Helbing, 1922 and Nimravidae gen. et sp. indet. (Certainly belonging to one the two already identified species), the Ursida Pachycynodon crassirostris Schlosser, 1888, Pachycynodon sp., Amphicynodon sp. 1 cf. A. typicus (Schlosser, 1888), Amphicynodon ? sp. 2 and Ursida gen. et sp. indet. cf. Pachycynodon boriei (Filhol, 1876), the Mustelida M. olivieri Bonis, 1997, the Carnivora incertae sedis Palaeogale sectoria (Gervais, 1848-1852), the Arctoidea gen. et sp. indet. and Carnivora gen. et sp. indet. (probably representing taxa already identified at lower taxonomic levels). The evolutionary grade of B. gregarius of Valbro compares to that of the species from Mas de Got, La Plante 2 and Cavalé, which supports an MP22 age for Valbro. This datation is further supported by the association of Theridomyinae yielded by the locality (B. gregarius, B. gemellus, I. medius and S. cayluxi), and by the presence of a N. intermedius that well compares the material of the species from Villebramar, La Plante et Mas de Got, of D. bonali, P. sectoria, M. olivieri (species known only from Mas de Got), and by additional evidence from the remaining vertebrates from Valbro, especially the squamates. Despite a limited amount of specimens (341 specimens have been studied), the faunas of rodents and carnivores from Valbro are the most speciose and diverse known for the MP22 level and, for the Carnivora fauna in particular, for the Oligocene of the Old World.