PALM TRUNK IN THE CAMPANIAN OF NEUQUÉN GROUP, NEUQUÉN PROVINCE, ARGENTINA. In this paper a new species of fossil palm is described from the Auca Mahuevo locality, where the Anacleto Formation (Campanian) crops out, in the Neuquén province, Argentina. The described fossils correspond to palm trunks, referred to the genus Palmoxylon Schenk. These stems were compared with other species of this genus and with extant representatives of the family Arecaceae, and such comparisons allowed to assign it to a new species, Palmoxylon garridoi sp. nov. Martínez. The fossil record of palms in the Anacleto Formation suggests warm climate conditions in the Campanian of the Neuquén Group, and also extends the biochron of this genus in Argentina.