A revision of the late early Eocene mammal faunas from Mas de Gimel and Naples (Montpellier, Southern France) and the description of a new theridomorph rodent

European terrestrial mammal sites dated from the late Ypresian are predominantly known from the Paris Basin. In Southern Europe (France and Spain), some localities are also known, but all have only yielded small faunas, composed by few taxa. An exception is the rich locality of Mas de Gimel (city of Montpellier, Hérault, France), which has long been considered the reference fauna of the late Ypresian in Southern Europe. Curiously however, only the rodents, artiodactyls and metatherians from this key locality have been studied in detail since the 1960s. Here, based on the original collection housed in the University of Montpellier, we revise the entire mammal taxa, which leads us to identify 38 species among 12 orders. We also study the close and co-eval localities of Naples and Naples 2, where we identify 23 species among 10 orders. Among the species identified from the three localities, we describe the new theridomorph rodent Hartenbergeromys pailladensis n. sp., characterized by numerous thin high extra ridges on upper and lower molars. Compared with the four standard MP (Mammal Paleogene) reference-levels for the European Early Eocene (MP7, MP8+9, MP10a, and the putative ‘MP10b’), the faunal assemblage from Mas de Gimel and Naples is attributed to the MP10a, representing a major European reference for this period. This study also supports the idea that, during the late Ypresian, the mammal faunas from North- and Southwestern Europe are quite homogeneous.