Superclasses are an intermediate classification rank directly above a class. They rank below a phylum or subphylum and contain one or more classes. The tetrapods are a superclass that includes the amphibian, reptile, bird, mammal and dinosaur classes.
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories. The rank of species, and specification of the genus to which the species belongs is basic, which means that it may not be necessary to specify ranks other than these.