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Rhinophrynus dorsalis is the only living member of the family Rhinophrynidae. It is one of the strangest of frogs. This animal is highly fossorial (adapted for burrowing) and apparently only comes to the surface to breed, and then only during very heavy rains. The head is small and cone-shaped, and not surprisingly, the skull resembles that of a mole (Spalax). The skin is quite thick, and an early naturalist described the frog (in French) as a bag of bones. It ranges through the southern Rio Grande Valley of Texas to Costa Rica. This frog is 5-7 cm long. There is usually a broad red or orange stripe down the middle of the back. There is a spade, used for digging, on the inner edge of the foot; the first toe is also modified to extend the functional edge of the spade.
Rhinophrynus dorsalis is specialized for eating termites, and the tongue seems to be particularly modified for this activity. Instead of being flipped out over itself, as in most frogs, the tongue is projected straight out of the mouth (Trueb, 1983).
Many small eggs are laid in water, and the tadpoles aggregate and form large schools. They are specialized for filter-feeding on small particles suspended in the water, rather than grazing on algae or eating detritus from the bottom of the pond. Correlated with this behavior, the larvae lack beaks and denticles; they also have paired spiracles like most pipid tadpoles. This type of tadpole (Orton Type 1) is evidence of a close phylogenetic relationship between Rhinophrynidae and Pipidae.