This study deals with the paleoenvironmental changes in northern Greece during the late Vallesian and the early Turolian, before and after the last occurrence of the hominoid Ouranopithecus macedoniensis. Dental microwear of fossil bovids yields information on paleodiet; thus, inferences can be drawn about floristic composition and paleoenvironmental changes. The microwear pattern of the fossil species is compared with that of extant species from the database “Ungulates” (20 extant species and 471 wild-shot specimens) in a multivariate analysis. The bovids of the late Vallesian “Ravin de la Pluie” locality show a dental microwear pattern similar to that of the extant grazers. This attests to the presence of open landscapes with an important grassy herbaceous layer in northern Greece during the late Vallesian. The bovids from the early Turolian also grazed. Nevertheless, Tragoportax rugosifrons, which constitutes the largest sample from the Turolian “Ravin des Zouaves 5” locality, was a mixed feeder. These dietary adaptations indicate an environment of bushy and/or wooded areas with a grassy herbaceous layer. The abundance of the mixed feeders in the ungulate assemblage of this latter locality also points out strong seasonal fluctuations in food availabilities.