The purpose of this application, under Article 23.9.3 of the Code, is to conserve at both the family and superfamily level the widely used family-group name Tyrannosauridae (-oidea) Osborn, 1906 (Dinosauria, Theropoda), which is threatened by its senior subjective synonyms Deinodontidae (-oidea) Cope, 1866 and Dryptosauridae (-oidea) Marsh, 1890. Strict application of the Code would result in unnecessary confusion in dinosaur taxonomy since the names Tyrannosauridae and Tyrannosauroidea have been used consistently in the vertebrate paleontological literature since the 1970s with only a very few exceptions.