Possibilities of determining the age of the raccoon dog (Nyctereutes procyonoides Gray) on the morphological variability of the skull
Chashchukhin V.А., DSc in biology, professor, leading researcher,
Solov'ev V.A., PhD in biology, senior researcher,
Lipatnikova S.V., engineer-researcher
Russian Research Institute Of Game Management And Fur Farming
Skulls of 53 raccoon dogs were examined. Skulls were distributed in ranks according to the degree of transformation of the chewing surfaces of molars in the upper and lower jaw. In each row skulls were selected with the most typical age-related changes of the chewing surfaces of molars. Then the age of raccoon dogs was determine by counting of annual layers in the cement on the cross sections of the upper canines. Transformation of the chewing surfaces begins from the second year of life raccoon dogs is visually noticeable. Initially the top of the mounds and ridges on the lingual side of the molars of the upper jaw begin to wear. From the fourth year of life tubercles in the center molars begin to fade. In individuals of seven-year age chewing surface of the molars is almost flat from the lingual side. On the buccal side the base paracone and metacone survived. In the lower jaw chewing surface transformation is most noticeable on the example of predatory teeth M1. The results of the laboratory determination of the age logically correlated with the variability of molars form in individuals up to the age of four years. The results of age determining in more adults were questionable because of the high individual variability of the form and the chewing surfaces of teeth. Peculiarities of development of the ridges on the lateral surface of the mandible were registered. It was noted the specificity of formation of the occipital and sagittal ridges due to the age of the chewing muscles. These results open the possibility of reliable determination of the age of juveniles which are usually prevalent in populations of raccoon dogs.
Keywords: raccoon dog, skull, teeth, age
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