The Order Struthioniformes comprises of large, flightless birds that includes the ostrich, emu, kiwi, and rhea. This group of birds have many synonyms, such as Ratites, which is derived from the fact that they lack a keeled sternum which is needed to anchor the wing muscles required for flight. Another synonym is the Palaeognathous birds, which identifies that these birds have a unique palate structure compared to other birds. Additionally, Struthioniformes is also referred to as the Struthionids, which is derived from one family within the order composed of the ostriches. Despite having different names, all of these synonyms unequivocally identify this flightless group of avians.