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a genus of gigantic extinct amphibians of the superorder Labyrinthodontia. The body measured up to 5 m long. The triangular head was disproportionately large and had an elongated snout and very large orbits. The body was broad and flat, and the extremities were short. Mastodonsaurus lived in the Middle and Upper Triassic epochs in Central Europe and in the southern foothills of the Urals. It was a bottomfeeding predator, dwelling in freshwater.