Mitsuo Iwamoto

Two macaque fossil teeth from the Japanese Pleistocene

Two fossil teeth of the Pleistocene macaque of Japan are stated to be those ofMacaca cf.fuscata. One of them is a lower canine tooth found in the Shiriya mine in northern Japan. It has been thought that the fossil assemblage of the Shiriya mine is of the late Pleistocene. The canine concerned is not distinguishable from the lower right one of the living female Japanese monkey. The other is a lower molar taken from the Ando quarry in western Japan. The fossil assemblage from the Ando quarry or from sites neighbouring the quarry indicates that the age of the molar can be traced back to the middle Pleistocene. The molar concerned has a somewhat buccolingually depressed crown as compared with that of the living Japanese monkey (Macaca fuscata).

Somatometrical features of Japanese monkeys in the Koshima islet: In viewpoint of somatometry, growth, and sexual maturation

The Japanese monkeys inhabiting Koshima islet were investigated morphologically, and compared with those living in other areas of Japan. The morphological features of the Koshima monkeys are thought to reflect many interrelated factors. Their body size is the smallest inMacaca fuscata fuscata. The lower latitude and the warmer winter of the islet represent the major factors in this small body size. Another physical characteristic is their longer limbs, which may be related to the same environmental factors. The adult males of the Koshima troop show the widest variation, while the variation in the adult females is the narrowest, among the troops ofMacaca fuscata examined. This may be explained either by sexually differentiated growth, that is, males continue to grow considerably after 8 years of age, whereas females do not; or by isolation, that is, males sometimes immigrate into or emigrate from the islet, whereas almost of all the females remain there. It was found that the influence of food limitations on body weight depends on sex and age; babies and juveniles, and adult males did not lose their body weight, but monkeys aged from 3 to 7 years and adult females had lost much weight compared to those of the same ages and sexes measured in 1963 (feeding was not limited). This fact may support the idea of “sex-age-class selection” proposed byMori (1979), but the weight loss pattern could be explained by changes of body composition with growth. The growth of the anterior trunk length, too, was restrained. Sexual maturation in males was delayed by at least one year.

Morphological studies ofMacaca fuscata

Dermatoglyphics of the foot of two groups of Japanese monkey (Macaca fuscata fuscata of Takasakiyama, Oita Prefecture andMacaca fuscata yakui of Yakushima, Kagoshima Prefecture) were examined. All the fingerprints of the foot consist of a whorl type. Concerning plantar patterns and ridge directions in the sole, there are some differences between both groups. Common to both groups, we find that three kinds of interdigital pattern (II, III, and IV) and proximal thenar pattern (Thp) are usually of the non-whirling type. This comparatively low frequency of occurrence of a whirling type may be regarded as a characteristic of this species (Macaca fuscata).

On a skull of a fossil macaque from the shikimizu limestone quarry in the Shikoku district, Japan

An almost complete calvaria of an adult macaque was found among remain from the Shikimizu limestone quarry at Hijikawa-cho, Kita-gun, Ehime Pref., Shikoku, Japan. Its exact age is unknown, but probably Pleistocene because mammalian bones from this quarry include not only recent but some Pleistocene elements. The Shikimizu skull has a somewhat different feature as compared with the skull of livingMacaca fuscata, mainly in that its facial region is much broader. In this feature, the Shikimizu skull seems to somewhat resembleMacaca robustus from China, suggesting that the older the lineage offuscata is traced back in the Pleistocene, the more its ancestral type would becomerobustus-like in the morphology.

Morphological studies ofMacaca fuscata: VI. Somatometry

Measurements of various parts of the head and body and weighing the body were carried out on about 170 adult Japanese monkeys (Macaca fuscata) and the results are noted with separate statistics for respective local groups. Intraspecific comparisons in the Japanese monkey and interspecific comparisons in macaques are discussed from the somatometrical point of view. Among macaques, the Japanese monkey has a comparatively large body, a very short tail, relatively wide biacromial and biiliac breadths, and markedly la ge intermembral and intercrural indices. The Japanese monkey itself shows various local variations. The most conspicuous difference is to be found between the so-called Yaku monkey living on Yaku islet (Yakushima), south of Kyushu, and the monkeys living in other parts of Japan, and, therefore, it is understandable that the Yaku monkey has been distinguished as a subspecies (M. f. yakui) of the Japanese monkey. The Yaku monkey has a somewhat small body, a relatively large head, wide hips, and slender hands and feet.

A fossil baboon skull from the lower Omo basin, southwest Ethiopia

A well-preserved fossil skull assignable to the genusPapio was discovered in the late Pliocene deposits at the “White Sands locality” of the lower Omo basin, southwest Ethiopia in November 1978. This skull obviously belongs to a male baboon which is morphologically somewhat different from the extant species ofPapio and closely resemblesPapio baringensisR. E. F. Leakey, 1969. Its muzzle is not only long but comparatively wide and robust with a very flat dorsum, an almost quadrate vertical cross section, short and obtuse maxillary ridges and virtually absent maxillary fossae, and its zygomatic portion flares laterally to widen the large temporal process of the zygomatic bone. The post-orbital constriction is very marked, the temporal fossa is squarish in basal view, and the sagittal crest is placed rather posteriorly and meets a large nuchal crest, all of which suggest heavy temporal musculature. The incisors are lacking but were probably not as small as inP. baringensis. As a result of morphological comparisons with extant and fossil species ofPapio, this newly discovered skull was considered to represent a new species,Papio quadratirostris.

Case report on a Japanese monkey with congenital malformation of the limbs

The case of an extremely limb-malformed Japanese monkey born in the Miyajima troop in 1970 is described. The limb defect is almost symmetrical on both sides. The forelimb lacks its hand, and the hindlimb appears as if it were only a small wart. No marked chromosomal abnormalities for this malformed monkey could be found.

The pterion in crab-eating macaques

The cephalic index increases steadily to adult in this survey, as well in other primate, contrasting with man, but the length-height and breadth-height indices decrease with age. The facial and upper facial indices increase during growth, whereas the nasal and interocular indices decrease with age. In comparing the body proportions of the Japanese monkey with those of other primates, particularily, in comparing those of the adult stage, the body build, head shape and facial type of the Japanese monkey approaches most closely to those of the macaque monkeys (Macaca irus, Macaca mulatta).