ホンドキツネ (Vulpes vulpes japonicus) の歯と下顎骨についての比較解剖学的研究

概要

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A comparative anatomical study was made of the upper and lower teeth and mandibula with use of 35 skulls of the Japanese fox captured in Kyushu. The results were as follows : 1. As the characteristics in tooth size of carnivorous animals, canine teeth were large and strong and carnassial teeth were well developed. Among the incisor teeth, I_3 was the largest followed by I_2 and I_1. As to molars, the carnassial tooth was the largest and further away from it anteriorly, and posteriorly the teeth were successively smaller. 2. The mesial and distal tubercles located on the lingual surface of incisor teeth were less developed than those of the dog family but were well developed as compared with those of the members of the cat family. 3. Metaconus located on the occlusal surface of the upper premolar teeth was hardly developed at P_1, P_2, and P_3, but was quite developed at P_4. The upper carnassial tooth, a tritubercular tooth which is large mesiodistally, was quite similar in the form of the occlusal surface to that of other members of the dog family. This form differs from that of racoons whose P_4 is a quadritubercular tooth, and differs also from that of the members of the cat family whose P_4 has sharply pointed cusps. 4. The mesial and distal tubercles at the lower premolar tooth were poorly developed as compared with other members of the dog family. Development of the mesial tubercle was especially poor. The distal tubercle was most developed at P_4. Hypoconid hardly appeared at P_1, P_2, and P_3, but its appearance was seen in 71.4% of P_4. The size of hypoconid was larger as compared with other members of the dog family. 5. The crown of upper distomolar teeth consisted of four main cusps. The highest was paracone for M_1 and protocone for M_2. The lowest was hypocone for all. The proportion of talon to the whole crown was lower for both M_1 and M_2 than that of racoon dogs. 6. As to lower distomolar teeth, the occlusal surface of M_1 which is a carnassial tooth consisted of five main susps. Of these, protoconid was the most developed. Paraconid was next in size. Entoconid was the least developed of all. For M_2, however, paraconid had disappeared and for M_3 only protoconid and metaconid were found and other cusps were not observed. 7. In size, the mandibula was smaller in length and height than that of the beagle dog but greater than that of the racoon dog. In comparison between coronoid process and condylar process, the former was markedry higher, as in other carnivourous animals. 8. The form of the mandibular head was elliptic, elongated in the right-left direction, as in other carnivorous animals. Its index was 36.8, which is not greately different from that of other members of the dog family but greater than 28.1 of the bobcat of the cat family. A comparison with omnivorous pigs and wild boars with an index of 100 or over indicates a significantly different form. 9. The mandibular notch showed an index of 22.8, indicating marked shallowness. As compared with other members of the dog family and other herbivorous and omnivorous animals, the Japanese fox has a very shallow mandibular notch. 10. Three mental foramens were found. Of these, the middle foramen with an average diameter of 1.82 mm was the largest and was located around a point below P_1. Vertically, it was located at a point slightly below the center and its direction of opening was toward the front in most cases.
九州歯科学会の論文
1985-10-25

著者

杉原瑛治
九州歯科大学口腔解剖第一講座

ホンドキツネ (Vulpes vulpes japonicus) の歯と下顎骨についての比較解剖学的研究

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