A ratite is any of a diverse group of large, flightless birds of the order palaeognathae originating on the supercontinent Pangea. There is still some controversy regarding the systematics involved. Some sources state that Ratites are synonymous with Struthioiniformes, while other sources state that Ratites are the same group, only that the order Struthioniformes contains only the Ostrich and possibly the Elephant Bird. Ratites belong to the modern bird family Palaeognathe which consists of ratites and tinamous (compare to Neognathae) . Unlike other flightless birds, the ratites have no keel on their sternum—hence the name from the Latin ratis (for raft). Without this to anchor their wing muscles, they could not fly even if they were to develop suitable wings.
Most parts of the former Gondwana have ratites, or did have until the fairly recent past. Their closest living relatives are the tinamous of South America.
Some taxonomical systems consider the various families of ratites to be orders, but the system used here uses the order "Struthioniformes" to refer to all ratites.
Read more about Ratite: Evolution and Classification, Physical Characteristics, Ratites and Humans