This research focused on the developmental patterns of crania, dentition, and postcrania among wild Pongo pygameus. Skeletal parts investigated in this study were as follows : tooth eruption and wear progress, cranial sutures, proximal and distal joints of long bones, clavicle, pelvis. As size variables, size of dentition, cranial, and long bones were also measured. Analysis of developmental stages of teeth and several skeletal joints revealed the several distinct aspects of orangutan development. Those are listed below.
1. Development, maturing and aging of teeth, crania, postcrania occur more or less independently, especially in males. Therefore, the definition of adult should be done carefully. 2. Basal cranial suture (spheno-occipital synchondorosis) closes only after the completion of eruption of permanent dentition, and sometimes, molars show heavy wear by then. 3. The last postcranial parts to finish development are distal ends of forelimbs. The line of distal end of ulna and radius happens after the closure of basal cranial suture. Development, maturing and aging of crania and postcranial are supposed to be controlled by endocrinological factors which are in turn related probably with social behavior. In order to have better understanding of these interactions, it is necessary to carry out longitudinal study on captive orangutans in which morphological, endocrinological and behavioral variables should be studied at the same time. In addition, in order to approach the evolutionary, and adaptive significance of such developmental patterns of orangutans, a study of wild orangutans in which association between morphology and reproductive success is necessary.