This book provides insight on the osteology, myology, phylogeny and evolution of Osteichthyes. It not only provides an extensive cladistic analysis of osteichthyan higher-level inter-relationships based on a phylogenetic comparison of 356 characters in 80 extant and fossil terminal taxa representing all major groups of Osteichthyes, but also analyses various terminal taxa and osteological characters. And also provides a general discussion on issues such as the comparative anatomy, homologies and evolution of osteichthyan cranial and pectoral muscles, the development of zebrafish cephalic muscles and the implications for evolutionary developmental studies, the origin homologies and evolution of one of the most peculiar and enigmatic structural complexes of osteichthyans, the Weberian apparatus, and the use of myological versus osteological characters in phylogenetic reconstructions.This work may stimulate, and pave the way for, future studies on the comparative anatomy, functional morphology, phylogeny and evolution of osteichthyans and of vertebrates in general.