SKELETAL SYSTEM ANALYSIS OF ASIAN GIANT SOFT-SHELLED TURTLES AND COMPARISON WITH CHINESE SOFT-SHELL TURTLE

Asian giant soft-shelled turtle is one of the first class protected animals in China, and is an extremely endangered species. Now, there are only 13 sexually mature Asian giant soft-shelled turtles in captivity in China. Due to fill the blank in the study of Asian giant soft-shelled turtle skeleton system, this study described the morphological characteristics of the complete skeletal system of Asian giant soft-shelled turtles and Chinese soft-shell turtles, and draws a diagram. The frozen samples of two Asian giant soft-shelled turtles and one Chinese soft-shell turtle were studied in this study. After the processes such asdefrosting and dissection, we used larva of Tenebrio molitor to manufactured skull specimen of the turtles. Removed the bones and rinsed with water to dry them. Then the vernier calipers were used to measured each bone structure and take photos, and the shapes were hand-drawn with reference to the bone entities and photos. A total of 169 bone fragments were found, consisting of exoskeleton of dorsal and ventral armor, endoskeleton of midshaft bone and appendage bone. Meanwhile, the skeletal structure of Asian giant soft-shelled turtle and Chinese soft-shell turtle had significant differences in snout length and the third cervical spine structure. The ratio of the length from the anterior orbit of soft-sheller to the most tip of the muzzle to the total length of skull was 0.082 for Asian giant soft-shelled turtle and 0.570 for the Chinese soft-shell turtle. Although the number of cervical vertebrae bones of Asian giant soft-shelled turtle and Chinese soft-shell turtle was 9, the transverse process of the third to ninth cervical vertebrae of Chinese soft-shell turtle was more obvious, the cone of the seventh cervical vertebrae was obviously warped upward, and the front end of the abdominal cone of the ninth cervical vertebrae was pointed. From the whole cervical spine, the ratio of the length of the spine of to the length of its back armor is 0.66 for the Asian giant soft-shelled turtle and 1.07 for the Chinese soft-shell turtle. These results provide the basis for the identification of Asian giant soft-shelled turtles, the phylogenetic evolution and ecological adaptability of turtles, indicating that Asian giant soft-shelled turtles are primitive reptiles with an important role in animal evolution.