 The ratites are mostly large and long-legged, flightless birds, lacking a keeled sternum.Traditionally, all the ratites were place in the order Struthioniformes.However, recent genetic analysis has found that the group is not monophyletic, as it is paraphyletic with respect to the tinamous, so the ostriches are classified as the only members of the order Struthioniformes and other rattites placed in other orders.