The morphogenesis of the manubrium sterni was studied in a series of dated embryos of Tupaia belangeri. In addition to the sternal bands, the "paired suprasternal Anlage" takes part in the shaping of the manubrium sterni as reported by Klima (1968) for other mammals. It forms skeletal elements that mediate between the clavicle and the manubrium: the sternocalvicular ligament and the paired prominence on the dorsal surface of the manubrium, which underlies the clavicles. The paired prominence corresponds to the praeclavium present in some therians. Very probably, the discus articularis of the sternoclavicular articulation of some primates can be attributed to the suprasternal Anlage. There was, however, no indication that the ossa suprasternalia of primates develop from the suprasternal Anlagen: In Tupaia these Anlagen do not form the cranial part of the manubrium. Klima's "unpaired Anlage" develops differently in Tupaia than in other therians. It consists of connective tissue and is not integrated into the manubrium. It presents an insertion surface for the M. pectoralis major, which shifts its origin onto the manubrium, after the sternal bands have fused. The homology of the "unpaired Anlage" and the "pars chondralis interclaviculae" is doubtful.

The therian scapula was until now thought to show very primitive features during early morphogenesis, as are found in the scapula of adult monotremes (elevated position of the scapula, lack of a spina and a fossa supraspinata, laterally directed cavitas glenoidalis). A morphogenetic study of the scapula of Tupaia belangeri has proved some of these assumptions to be wrong. The scapula undergoes a tilting which shifts its angulus articularis cranially, but no descent of the scapula could be found. The supraspinous fossa, which was supposed to develop very late in ontogeny from the anterior border of the scapula (Lewis 1902, Cheng 1955), is present in Tapaiai from the start. Part of it ossifies in membrane. The scapular spine does not develop as a cartilaginous outgrowth from the anterior border, but is formed mainly as an appositional bone along the lateral surface of the scapula. The glenoid cavity and the humerus are initially directed laterally. They attain their definitive form after the heart has migrated downward and the arms have been adducted. This represents a true plesiomorphous character state in therian ontogeny.