科研之友
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摘要
Skulls from 1,085 California sea lions (Zalophus californianus) were examined macroscopically according to defined criteria. The museum specimens, 61.8% male and 37.3% female, were acquired from strandings and varied in age from juvenile to adult. The majority of teeth were available for examination (95.7%); 3.8% of teeth were artefactually absent, 0.4% deemed absent due to acquired tooth loss and 0.1% were congenitally absent. Acquired tooth loss was associated significantly with sex (P = 0.004) with males having more tooth loss than females and total ante-mortem tooth loss was associated significantly with age (P <0.0001) with adults having more tooth loss than young adults and juveniles. Eleven teeth were malformed and 81 teeth were observed to have two roots. Supernumerary teeth (usually maxillary molar teeth) were associated with 1.3% of teeth, some specimens demonstrating up to four supernumerary teeth. Thirteen persistent deciduous teeth were identified. A total of 713 specimens showed attrition or abrasion, with 42.4% of teeth affected. A significant association was detected between sex and incidence of abrasion and age and the incidence of abrasion (P <0.0001 for both associations). Males showed more abrasion than females and adults showed more abrasion than young adults or juveniles. Two hundred and sixteen fractured teeth were observed, with root fractures being most prevalent. Fractures were associated significantly with sex and with age (P <0.0001 for each association). Males had more fractures than females and adults had more fractures than young adults and juveniles. Bony changes consistent with periodontitis were found, affecting 19.4% of teeth. Males were shown to have more periodontitis than females and adults were shown to have more periodontitis than young adults and juveniles. Sixty-three periapical lesions were noted.
- 出版日期2014-7
