霊長類マカク属の大臼歯についての比較形態学的研究
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概要
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Morphological studies of teeth of primates are very important for elucidation of phylogenic aspects of teeth of mammals. Among the primates, catarrhina, in particular, along with anthropoid has a dental formula similar to human's and presents morphological similarities. For this study, rhesus monkeys, Japanese monkeys, and crab-eating monkeys of Macaca genus were selected and the crowns of the upper and lower molars were measured. The measurements were then compared with those of other primates and examined from a morphological standpoint. The results were as follows : 1. Mesiodistal diameters, buccolingual diameters, and occlusal surface areas of the upper and lower first molars were significantly larger in Japanese monkeys than in crab-eating monkeys or rhesus monkeys. A similar tendency was seen for the second and third molars. 2. Among the primates, the sizes of the teeth of Macaca genus fell within the same range of the teeth of other catarrhina, and were larger than platyrrhina's and smaller than hominidae's. 3. The crown indexes for the upper and lower molars of Macaca genus were all larger than 100 and the mesiodistal diameters were larger than buccolingual diameters. The mesiodistal diameters for the lower jaw in particular were significantly larger than those for the upper jaw. Catarrhina showed larger indexes as compared with platyrrhina and hominidae. In contrast with catarrhina, most species of platyrrhina and hominidae showed indexes less than 100 especially for the upper jaw, and the buccolingual diameters were larger than the mesiodistal diameters. 4. Examination by the distal crown diminution index of the difference between the mesio-buccolingual diameter and disto-buccolingual diameter shows that the mesial side is generally larger than the distal side. The diminution rates of the distal side were more marked for the upper jaw than for the lower jaw. The more posteriorly positioned a tooth was, the greater the diminution rate was, as the third molar was greater in value than the second molar, which in turn was greater than the first molar. The diminution indexes for Macaca genus tended to be slightly larger than those for other primates although the differences were small. 5. In Macaca genus, second and third molars were larger in size as compared with first molar. However, there was some difference between the upper and lower jaw in the trend for the teeth on the distal side to increase their size. In the upper jaw, although second molars were larger than first molars, there was little difference between second and third molars. In crab-eating monkeys, third molars were more diminished in size than second molars. In the lower jaw successive increase in size was seen from first molar to second molar and to third molar. 6. Although the teeth positioned posteriorly to first molar increase thier size in Macaca genus, the teeth on the posterior side in anthropoid and hominidae tend to diminish. This tendency is quite marked especially in human. In other words, regression of molars from the posterior side is seen in hominidae, while such occurrence has not yet been recognized in Macaca genus.
- 九州歯科学会の論文
- 1983-12-25