Sex differences of the hipbone were compared among closely-related 5 species of Macaca; M. fuscata, M. mulatta, M. fascicularis, M. cyclopis and M. radiata. Nine measurements were taken from the hipbones and eight indices were obtained by standardization using the maximum pelvic height. Sex differences of the measurements and indices were tested by Student's t-test and a principal component analysis (PCA) was conducted using the eight indices to examine general patterns of sex difference in these species. The results showed that male measurements were larger than females except the pubic length. The maximum pelvic height, the maximum acetabulum diameter, and the length of the ischium were significantly larger in males than females in the examined species except for M. fascicularis. The relative length of the ilium and the relative pubic length were both significantly larger in females than males. The relative length of the ischium was significantly larger in males for all the examined species. The pattern of the sex differences was common among the examined Macaca species. The first principal component of the PCA represented sex differences. The second principal component separated macaque species, though some overlaps were observed. Therefore, the shape variation of the hipbone among Macaca was largely explained by the intraspecific sex difference (33%) rather than the interspecific difference (20%). It is suggested that the external shape of the hipbone among macaques is more influenced by obstetrical functions rather than locomotory functions.

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The maxillary sinus communicates with the middle meatus of the nasal cavity through a narrow ostium. Here, I have surveyed variations in the maxillary sinus anatomy of extant and fossil anthropoids which have been examined using computed tomography (CT). The CT studies have identi.ed the sinus by its ostium that opens exclusively to the middle nasal meatus, because the ostium marks site from which the pneumatization to form the sinus begins. A sinus pneumatizing the entire maxilla is shared by all extant hominoids. In contrast, cancellous bone completely .lls the maxilla in extant cercopithecoids, with the exception of macaque monkeys which have a small sinus. Among platyrrhines, the entire maxilla is pneumatized by the sinus in the Atelidae, Cebus, and Callicebus, whereas only the medial part of the maxilla is pneumatized by the sinus in the Callitrichinae and Aotus. Pithecia exhibits a unique conformation in which the maxillary sinus and another cavity expands from the inferior meatus pneumatize the posteromedial and anterolateral parts of the entire maxilla, respectively. Saimiri has no sinus, as in the case of cercopithecoids excluding macaques. In Chiropotes and maybe Cacajao, the inferior meatus expands into the area between the middle meatus and medial surface of the maxilla thereby disturbing sinus formation. The sinus was lost independently in Saimiri and Cacajao-Chiropotes clades, and in the common ancestor of cercopithecoids. The sinus pneumatizing the entire maxilla is argued to be a primitive feature in anthropoids. This hypothesis is supported by the results from studies of fossil anthropoids. This information may be relevant to the phylogenetic analyses of unclassi.ed fossil anthropoids. I hope this paper will also stimulate future studies on the variations in sinus anatomy in prosimians and other mammals, and on other inner structures of the cranium in primates. Potentially, such information probably will further facilitate the phylogenetic analyses of fossil specimens.

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