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1 June 2014 Functional osteology of the forelimb digging apparatus of badgers
Jacob Rose, Alexis Moore, Anthony Russell, Michael Butcher
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Badgers (Carnivora, Mustelidae) constitute a nonmonophyletic assemblage of mammals that are characterized by a general similarity of appearance and a broad geographic distribution. A comparative analysis of the forelimb osteology of badgers was performed to assess how observed differences in their scratch-digging behavior are related to variation of forelimb structure. We measured forelimb bone proportions of 87 skeletal specimens and calculated 8 functional indexes that were analyzed using analysis of variance and principal component analysis to identify the osteological correlates of fossorial ability in this clade. The indexes that best characterize forelimb specialization for scratch-digging in badgers are related to a robust humerus, large humeral epicondyles, and a long olecranon process, and these features increase from digger to semifossorial forms. A large scapular area for muscle attachment and a robust ulna also are correlated with fossorial ability. Semifossorial forms are indicated to have greater forelimb muscle mass, increased mechanical advantage of the elbow extensors, and the ability of the elbow extensor and carpal and digital flexor muscles to apply high out-force to the substrate. Digger forms are indicated to have relatively less robust and longer distal limb bones, and lower limb out-force capability. This study reveals that for badgers there is a distinct relationship between the proportions of the forelimb bones and fossorial ability. The indexes tested that relate to mechanical advantage of the elbow extensors and mass and force production capacity of the musculature have the discriminatory ability to distinguish between degrees of forelimb specialization and fossorial ability of badgers.

Jacob Rose, Alexis Moore, Anthony Russell, and Michael Butcher "Functional osteology of the forelimb digging apparatus of badgers," Journal of Mammalogy 95(3), 543-558, (1 June 2014).
Received: 15 July 2013; Accepted: 1 February 2014; Published: 1 June 2014

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