Christiansen Per
Zoological Museum, Universitetsparken 15, 2100 Copenhagen Ø, Denmark.
J Morphol. 2008 Jul;269(7):896-908. doi: 10.1002/jmor.10643.
The morphology and mechanical strength of the upper canines in all eight extant species of ursids is analyzed, and the findings are discussed in relation to feeding ecology. Ursids have proportionally smaller canines than other large carnivores with a specialized feeding ecology, such as large felids, and the upper canine morphology is both canid-like and felid-like. The giant panda is the most divergent species, and its short, blunt, and cone-like canines appear well adapted for tearing into bamboo. The almost equally herbivorous spectacled bear has a less derived canine morphology. The large canines of the sun bear are divergent from other ursine ursids, and may be an adaptation for tearing open tree trunks in search of insects. Discriminant Analysis is successful in separating ursid species on the basis of canine morphology, but the canines of ursine ursids, and also of the spectacled bear, show greater resemblance among the species than the marked differences in feeding ecology would suggest. This could be in part due to a short evolutionary history, and in part due to canines not having been subjected to much evolutionary selection as has been the case among other large carnivores, such as large felids. Ursids are probably evolutionarily and ecologically successful due to physical size and strength rather than a derived craniodental anatomy.
分析了现存8种熊科动物上犬齿的形态和机械强度，并结合觅食生态学对研究结果进行了讨论。与其他具有特殊觅食生态学的大型食肉动物（如大型猫科动物）相比，熊科动物的犬齿相对较小，并且上犬齿的形态既类似犬科又类似猫科。大熊猫是差异最大的物种，其短而钝的锥形犬齿似乎非常适合撕咬竹子。几乎同样以草食为主的眼镜熊的犬齿形态则没有那么特化。马来貘的大犬齿与其他熊科动物不同，可能是为了撕开树干寻找昆虫而形成的适应特征。判别分析成功地根据犬齿形态区分了熊科物种，但熊科动物以及眼镜熊的犬齿在物种之间的相似性比觅食生态学上的显著差异所表明的要大。这可能部分是由于进化历史较短，部分是由于犬齿没有像其他大型食肉动物（如大型猫科动物）那样受到太多的进化选择。熊科动物在进化和生态上可能是成功的，这得益于其体型和力量，而非特化的颅齿解剖结构。
