Ordine degli uccelli suddiviso in quattro sottordini:
Bibliografia G. R. de Beer “The evolutions of ratites” Bull. British Museum Natural History (1956) A. H. Bledsoe “A phylogenetical analysis of postcranial skeletal characters of the ratite birds” Ann. Carneg. Mus. (1988) W. J. Bock „The cranial evidence for ratites affinities“ (1963) P. Cho, R. Brown, M. Anderson “Comparative Gross Anatomy of Ratites” (1984) J. Cracraft “Phylogeny and evolution of ratites bird” (1974) Ernst Mayr “Struthioniformes” (1979) C. Tyler, K. Simkiss “A study of the egg shells of ratide birds” (1959) Vedi anche: Uccelli/Classificazione