During his nearly 50-year long career Louis de Bonis has positively and markedly influenced many generations of paleontologists. In this introduction to the volume celebrating the 75th birthday of this French outstanding scientist, we present and discuss the significance of his many contributions to the study of mammalian evolution, focusing especially on his works on primate and carnivoran systematics and evolution, and on his involvement in field excavations in northern Greece Ouranopithecus-bearing sites.