This article describes the anatomy of the dorsal and ventral cephalic musculature of Gymnura marmorata, G. micrura, Aetobatus narinari, Myliobatis californica, M. longirostris, Rhinoptera steindachneri, Mobula munkiana, and M. thurstoni. It was observed that muscles of the dorsal cephalic region showed little variation among species, with the exception of the dorsal longitudinal bundles and the cucullaris muscle. The ventral cephalic musculature showed wider differences, mainly in the depressor hyomandibulae, coracomandibularis, and mandibular adductor muscles. M. munkiana and M. thurstoni revealed a significant muscle reduction, while M. californica, M. longirostris, A. narinari, and R. steindachneri showed a significant development of the ventral cephalic musculature. The species in this comparative study were clearly grouped based on their feeding habits. Data gathered on the muscle arrangements correspond to other taxonomy studies conducted on these groups. However, the results of this study agree only partially with those from previously described phylogenetic models. Therefore, further phylogenetic research is recommended. Anat Rec Part A 271A:259–272, 2003. © 2003 Wiley-Liss, Inc.