Size, but not shape, would reflect mandibular differences in two spear-nosed bats (Phyllostomus Lacépède, 1799) (Chiroptera, Phyllostomidae)
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The mandible is a model for the evolution of complex morphological structures because it presents a developmental integration of its different parts. Unlike other parts of the skull that harbour different functions (protect-ing the brain and sensory organs), the mandible's main functional demands are
related to feeding, and dietary changes are expected to be the main selective agent for its structure. Here it is presented a geometric morpho-metric study of mandibles belonging to two species of New World leaf-nosed bats, Phyllostomidae: Pale Spear-nosed Bat (Phyllostomus discolor Wagner, 1843) (n= 29) and Greater Spear-nosed Bat [Phyllostomus hastatus (Pallas, 1767)] (n= 6), both of them with an omnivorous with a nectarivorous shift feeding habit. Differences in size and shape of mandible were examined using 13 landmarks plotted on lateral aspect. The results revealed species differences for size but not for shape, being allometry an unimportant component of interspecific varia-tion. It is concluded that similar feeding specialization in both species would have evolved towards similar man-dibular shape, with size having evolved quite independently in both species.