Chapter 4 concentrated mainly on the results relevant to the actinopterygians (the group that includes extant cladistians, chondrosteans, ginglymods, halecomorphs and teleosts), but it also compared the head and neck muscles of those fi sh with the musculature of some sarcopterygians. Chapter 5 focuses mainly on sarcopterygians (the group that includes extant actinistians, dipnoans and tetrapods: see Fig. 5.1) and particularly on how the head and neck muscles evolved during the transitions from sarcopterygian fi sh and non-mammalian tetrapods to monotreme and therian mammals, including modern humans. Tables 5.1-5.8 summarize the best-supported hypotheses of homology for the head and neck muscles of the sarcopterygian taxa listed in those tables. Importantly, Tables 5.1, 5.3, 5.5 and 5.7 also include comments about the development and muscular variations/abnormalities of our own species, Homo sapiens, which are presented mainly, but not exclusively, in the righthand columns of these tables.