The order of the Struthioniformes has only the family Struthionidae which include 2 species, The Common Ostrich and Somali Ostrich. A time ago also the Cassowary, Emu and Rheas were included. Nowadays the ornithological biologists have placed the Rheas into the order of the Rheiformes and the Cassowary and the Emu into that of the Casuariiformes.