The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Comparing Forelimb Skeletal Anatomy in Gray Squirrels and Primates


Anthropology, Hunter College

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Studies of primate locomotor anatomy and kinematics have demonstrated that arboreal primates have highly mobile shoulder joints and use greater forelimb protraction during quadrupedal locomotion compared to terrestrial mammals; these traits are argued to reflect adaptations for terminal branch foraging and locomotion. Eastern grey squirrels (Sciurus carolinensis) have recently been shown to engage in terminal branch foraging similar to arboreal primates, despite a lack of orbital convergence, opposable first rays, and other primate traits. Here, we examine the skeletal morphology of the gray squirrel forelimb to test for functional convergence with arboreal primates. Morphological characteristics of the scapula, humerus, and ulna, including the size of the humeral head, the size of the supraspinatus and subscapularis facets on the humerus, the length of forelimb bones, width and angle of the bicipital groove, the spinoglenoid angle and the supraspinatus facet angle, were examined in small-bodied arboreal primates and gray squirrels. Results suggest that the squirrel shoulder is similar in some ways to that of other small bodied primates, but reveal possible functional differences in the elbow.

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