Skull
All Mexican eleutherodactyline frogs have quadratojugal-maxillary articulations, completely roofed skulls in adults, median contact of the nasals, separated occipital condyles, and large prevomers. The premaxillae of all species are visible when the skulls are viewed from directly above. The pterygoid lacks a medioventral flange and does not meet the palatine. In no species is the anterior arm of the squamosal in contact with the maxillary. Of the numerous species examined (30 Eleutherodactylus, four Syrrhophus, and four Tomodactylus), the species in the Eleutherodactylus augusti group are unique in having a sphenethmoid with a blunt anterior edge.