Numerical vertebral variations and characteristics of deformed first lumbar vertebrae and lumbosacral regions in the Japanese black bear (<i>Ursus thibetanus japonicus</i>)

Nakamura Sachiko, Yokoyama Mayumi, Saita Erina, Morimitsu Yoshiki

doi:10.11238/mammalianscience.54.43

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ツキノワグマ（<i>Ursus thibetanus japonicus</i>）における椎骨の基本数と第一腰椎および腰仙結合部における形態変異
ツキノワグマ(Ursus thibetanus japonicus)における椎骨の基本数と第一腰椎および腰仙結合部における形態変異
ツキノワグマ(Ursus thibetanus japonicus)ニオケルツイコツノキホンスウトダイイチヨウツイオヨビヨウセンケツゴウブニオケルケイタイヘンイ

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Abstract

Japanese black bears (Ursus thibetanus japonicus) in Hyogo Prefecture exhibit abnormal bone morphology with high frequency. Basic knowledge about the bones of the Japanese black bear is necessary for diagnosis, for cause identification, and for evaluation of the influences of these abnormally formed bones on populations. This study analyzed the regular number and morphology of Japanese black bears vertebrae by comparison with those from three areas: Higashi-chugoku, Kita-kinki, and Iwate. The normal number of vertebrae in Japanese black bears is 7 cervical vertebrae, 14 thoracic vertebrae, 6 lumbar vertebrae, and 5 sacral vertebrae. When vertebrae of three kinds other than the sacral vertebrae were analyzed, three irregular patterns of vertebral combinations were observed. Each was found to be regionally idiosyncratic. Vertebral deformation of two types was identified. One type included extension of the transverse process of the first lumbar vertebrae. It was found more frequently in Kita-kinki. Another type included lumbosacral transitional vertebrae. It was found in Higashi-chugoku and Kita-kinki. Numerical variation of the vertebrae and vertebral deformation might be the result of different genetic characteristics of the three populations.

Journal

Honyurui Kagaku (Mammalian Science)

Honyurui Kagaku (Mammalian Science) 54 (1), 43-51, 2014

The Mammal Society of Japan

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