Ceratophrys cornuta is a striking frog due to the presence of its large mouth that is approximately 1.6 times wider than the length of the body. Adult females are larger (up to 120 mm and 130g) than adult males (up to 72 mm and 60g). (Duellman and Lizana, 1994). Color patterns are variable greens, browns, and beige with darker streaks of greens and browns. The ventral side shows a light colored body with uniform dark pigmentation on the throat (Lynch 1982). Like other members of the genus, C. cornuta possesses heavy calcification, ornamentation, casquing, and a hyperossified cranium. The skull is strong and akinetic, with all bones but the premaxilla, columellae, and the septomaxilla fused. A pronounced interocular crest characterizes this species. Other autapomorphies include the absence of a carina from the zygomatic region to the maxilla below the eye, the absence of vomerine teeth, pointed tubercles on flanks, smooth face, extensively webbed outer toes, and a slender, elongated tubercle on eyelids. (See Wild (1997) for detailed osteology).