Questions of comparative nature in biology require a systematic hypothesis. Prere- quisites are that the hypotheses are based on characters polarized by the cladistic methodology of outgroup comparison and that homologous structures are compared. Furthermore, both functional-experimental and comparative-evolutionary explana- tions can be incorporated into the phylogenetic hypotheses. Cladistics therefore, remains a potent tool for morphologists in order to deduce evolutionary explanations of structures. A posteriori hypotheses on evolutionary adaptations, convergent adap- tations, exaptations and non-adaptations of structures are then permissible.