TECHNICALLY speaking, the Crane-like birds, to go no further afield, may be said to possess, in common with the Galliformes on one side and the Charadriiformes on the other, the split (schizognathous) or incomplete band (desmognathous) form of palate, a double head to the quadrate bone, the distal ends of the ilium and ischium united, and no slip to the accessory femorocaudal muscle above the sciatic foramen. From the Fowl-like birds (Galliformes) the other two orders differ in having the basal end of the coracoids separate instead of united and crossed, in the absence of the spina interna sterni muscle, and in the bill not being decurved or vaulted, while the two orders are themselves diagnosed by the heteroccelous dorsal vertebra and 2-notched or entire sternum in the Gruiformes, and opisthocoelous dorsal vertebra and 4-notched sternum in the Charadriiformes.
In less technical language it may be stated that a majority of the forms included within the limits of this order are waders, though the Bustards, Wekas, Kagu, and others are preeminently terrestrial. All appear to agree, however, in the absence of a true crop, and in possessing an elevated hind toe, and always incompletely webbed front toes. But even admitting these relatively important points of agreement, the various groups differ quite widely in certain other structural characters, and the order seems on the whole a rather heterogeneous one, though it is perhaps as satisfactory a disposition as can be made at present. It embraces seven families.