New paroxyclaenid mammals from the early Eocene of the Paris Basin (France) shed light on the origin and evolution of these endemic European cimolestans

We present new species of an enigmatic family of mammals, which is endemic to Europe, the Paroxyclaenidae: Merialus bruneti sp. nov., Fratrodon tresvauxi gen. et sp. nov., Paraspaniella gunnelli gen. et sp. nov., and Sororodon tresvauxae gen. et sp. nov. The fossils described come from six localities of the Ypresian of the Paris Basin (France): Pourcy (MP7), Mutigny, Avenay, Condé-en-Brie (MP8 + 9), Grauves and Prémontré (MP10). They allow the description of three new genera and four new species belonging to the subfamilies Merialinae and Paroxyclaeninae. Two of these new species represent the earliest occurrence of each subfamily. Fossils from Mutigny, Avenay and Condé-en-Brie indicate that merialines were more abundant than paroxyclaenines during the Ypresian. Surprisingly, merialines disappeared from the fossil record at the end of the Ypresian – the youngest records are close to MP10 – while the paroxyclaenines were present in Europe until the end of the middle Eocene. Based on comparison with the data presently available for European mammals during the Ypresian, we suggest the existence of two periods of faunal turnover that must be more extensively studied in the future in order to be fully characterized: the ‘Intra-Ypresian Mammal Turnover’ and the ‘Ypresian–Lutetian Mammal Turnover’. Finally, because the oldest paroxyclaenids appear morphologically closer to cimolestids such as Procerberus than to pantolestans, it is suggested that similarities between paroxyclaenids and pantolestans could be due to convergence

Les lézards fossiles du Paléocène de Montchenot (Bassin de Paris, MP6)

Les faunes de lézards trouvées dans la localité de Montchenot (Paléocène supérieur, MP6, Est du Bassin de Paris) sont décrites. Ce matériel se répartit entre plusieurs groupes : Scincoidea, Lacertoidea (?Lacertidae), Amphisbaenia, Anguimorpha (?Anguidae et Shinisauridae). L’assemblage de Montchenot est dominé par des spécimens de petite taille, certainement le résultat d’un tri sélectif marqué. L’action de prédateurs peut produire de tels assemblages. Les taxons présents à Montchenot sont aussi présents, pour la plupart, dans deux gisements de même niveau (MP6) : ceux de Cernay-lès-Reims et de Rivecourt dans l’Est du Bassin de Paris. D’autre part, la faune de Montchenot diffère nettement (en composition et diversité) de celles reconnues dans les gisements de l’Éocène ancien (MP7) de la même zone géographique (Bassin parisien et belge). Ces diffèrences mettent en relief le fort impact de la transition Paléocène/Éocène sur les faunes de lézards.Here we describe the lizard fauna from the locality of Montchenot (Paris Basin, late Paleocene, MP6). This material can be allocated to five major clades: Scincoidea, Lacertoidea (?Lacertidae), Amphisbaenia, Anguimorpha (?Anguidae and Shinisauridae). The assemblage from Monchenot is dominated by small lizard specimens and appears as highly sorted. Predation could produce such biased assemblages. The composition of the lizard fauna from Monchenot is rather similar to those of Cernay-lès-Reims and Rivecourt, two coeval localities (MP6) in the Paris Basin. However, these faunas sharply contrast (in diversity and composition) with the lizard fauna found in the early Eocene of the same area (Paris Basin and Belgian Basin). These differences highlight the impact of the Paleocene/Eocene transition on the lizard fauna of Europe.</p