Field research in the Petites Pyrénées (France) yielded new Late Cretaceous continental microvertebrates, including some of the few known mammals from Europe from this time. They come from the well-dated late Maastrichtian Auzas Marls Formation which has yielded some of the latest European Mesozoic vertebrates. Here, we report new discoveries, including for the first time a co-occurrence of multituberculate and eutherian mammals in the Cretaceous of Western Europe, breaking previously known strong provincialism of Late Cretaceous mammals in Europe. Two new mammals are described. The kogaionid species Hainina cassagnauensis n. sp. is the first multituberculate known from the Late Cretaceous of Western Europe and the earliest record of Hainina. It makes Hainina one of the only known vertebrate genera crossing the K/Pg boundary in Europe. H. cassagnauensis n. sp. is the first described evidence for a mammal dispersal between the Eastern and Western parts of the European Archipelago at the end of the Cretaceous. Mammals from Tricouté also include an upper molar of the new eutherian cf. Azilestes yvettae n. sp. It exhibits an advanced morphology showing affinities to other specialized endemic eutherians from the Cretaceous of Europe such as Valentinella vitrollense and Azilestes ragei. These three European species have a basic zhelestid dental morphology, but their specializations suggest a new, at least subfamilial, European clade. As with other vertebrates from the European Archipelago, the kogaionid multituberculates and the zhelestid eutherians are ancient relict lineages that belong to the «old European faunal core».