The stegosaurian shoulder girdle was very robust. In "Huayangosaurus", the acromion, a process on the lower front edge of the shoulderblade, was moderately developed; the coracoid was about as wide as the lower end of the scapula, with which it formed the shoulder joint. Later forms tend to have a strongly expanded acromion, while the coracoid, largely attached to the acromion, no longer extends to the rear lower corner of the scapula. Ossified sternal plates have never been found with Stegosauria and perhaps the sternum was completely absent.