The trunk is relatively small, with few slender ribs and a keeled breastbone (sternum).
The technique in children over one year of age is the same as in adults, except that the amount of force used is less than that used with adults in order to avoid damaging the child's ribs, breastbone, and internal organs.
The fists are placed against the middle of the breastbone, and the motion of the chest thrust is in and downward, rather than upward.
In many birds the spaces between the metasternum and the posterior processes and again the spaces between this and the oblique process are filled up by proceeding ossification and either remain as notches, or as fenestrae, or they are completely abolished so that the breastbone is turned into one solid more or less oblong plate.
In conformity with these reductions the breastbone of the moas is devoid of any coracoidal facets; there is no trace of a keel, and the number of sternal ribs is reduced to three or even two pairs.