A Comparison of Eight Macaque Species According to Four Kinds of Cranial Nerve Perforations

Abstract

Eight species of macaques are compared according to the partitions observed in four kinds of cranial nerve perforations: hypoglossal canal, infraorbital foramen, stylomastoid foramen and mental foramen. Chi-square tests using 256 Japanese macaque crania showed virtual absence of a significant influence of age, sex and side factors on the cranial nerve perforations, which permits the maximization of sample sizes. Cluster analysis of a correlation matrix among right and left sides of the four characters and sex and age factors reveals that the characters segregate into "gnathic" and "basicranial" clusters and that sex and age factors join with "gnathic" cluster before the final overall connection. It is, however, concluded that the partitions of the cranial nerve perforations in macaques are virtually independent of age, sex and side factors and that intercharacter correlations among the four kinds of cranial nerve foramina are generally low except for the bilateral correlations.Though the overall pattern of the interspecific comparison through cluster analyses is not stable across the distance measures and clustering procedures applied, the derived positions of Macaca fascicularis among the four species of the fascicularis group and M. nemestrina among the eight species compared are repeatedly obtained. This interspecific pattern is also confirmed by principal component analysis.