By comparing the neurocranium of the "butterfly ray" Gymnura micrura with representative species of five families of Batoidea, it is recognized that it corresponds to the anatomical pattern of the order Myliobatiformes, because of the absence of the rostrum, the presence of a single fontanelle and the development of the postorbital processes. The species under study differs from the Urotrygonidae and Dasyatidae by having subdivided postorbital processes. The organization of the encephalon of G. micrura corresponds to the anatomical pattern of the Batoidea. However, unlike the Rhinobatidae, Urotrygonidae, and Dasyatidae, the cerebellum is symmetrical; in contrast with the Myliobatidae, the cerebral hemispheres are reduced; and, the main difference in relation to the Narcinidae, is the absence of electrical lobes.
KEY WORDS: Elasmobranchii; Cranium; Brain; Cranial nerves; Sensory organs.