SWIDERSKI, D.L.; SHEETS, H.D.; University of Michigan, Ann Arbor; Canisius College, Buffalo, NY: Divergence of scapula shape in Neotropical bats (Chiroptera: Phyllostomidae): inferences from combining landmarks and outlines

Phyllostomid bats have diverse diets (flying insects, fruit, nectar, small vertebrates, blood) and exhibit corresponding diversity in modes of flight used during foraging. Studies on many other mammals have shown that differences in forelimb function are reflected by differences in scapula shape. In this study, we investigate the relationship between scapula shape and modes of flight in selected phyllostomids. Twelve landmarks can be recognized consistently on the scapulae of these bats. Most of these landmarks are near the articulation with the humerus, and provide limited information about shape changes along the vertebral and axillary margins where landmarks are sparse. Differences between nectar feeding bats (which frequently hover) and vampire bats (which frequently take-off from the ground) are easily detected using only these landmarks, partly because they involve substantial differences in the acromion and the articulation surfaces of the joint, where landmarks are dense. Newly developed methods allow coordinates of semi-landmarks along the edge to be combined with coordinates of landmarks in geometric morphometric analyses. Analyses using a combination of landmarks and semi-landmarks along one edge discriminate among the same taxa and demonstrate that changes in relative widths of muscle attachment fossae on the blade are associated with changes in the curvatures of the edges of those fossa.