One of the several aims of evolutionary biology is to recognize the evolutionary branching order of organisms by means of phylogenetic reconstruction methods. In the last 20 years, other fields of evolutionary biology have undergone a dramatic progress. This is especially true for the study of the developmental basis of evolution (Raff & Kaufman, 1983; Raff, 1996), which has stressed the significance of development for evolution and vice versa. However, this new synthesis between developmental and evolutionary biology, prompted by the publication of Gould's (1977) Ontogeny and Phylogeny, has not yet been applied to phylogenetic studies of hominoid evolution. In our opinion, this situation cannot be maintained any longer, because morphological evolution cannot be properly understood without considering the constraining effect of development upon evolution. This raises the question of whether or not current widely used methods of phylogenetic reconstruction (i.e. cladistics), based on the use of extensive datasets instead of a deep understanding of individual characters, are reliable. After reviewing the significance of developmental constraints in evolution, we will argue that the reasons underlying the appearance of characters are absolutely relevant for phylogenetic analysis, and will try to exemplify their significance through the example of Oreopithecus bambolii, an extinct orthograde great ape of the late Miocene (c. 8 Ma) of the Tusco-Sardinian paleobioprovince. It is our contention that cladistic methodology is seriously flawed in several aspects and can give quite erroneous insights of phylogenetic relationships when evolutionary constraints as well as morpho-functional considerations are not taken into account.