The Beira Litoral area, in Portugal, which has yielded three main Late Cretaceous vertebrate localities was, at that time, an island. It thus constitutes a choice area for studying the role of insularity in extinction phenomena. It is clear that, in this area, faunal impoverishment and dwarfing, resulting from the reduction of terrestrial surface, were the prelude to the extinction, first of the large dinosaurs, and later, by climatic deterioration, of the small remaining forms. Consequently, in this case at least, it is not necessary to evoke catastrophic events to account for the extinctions observed.
Portugal, dinosaurs, Maastrichtian, insularity, extinction