Reptilian ear 3D morphometric data

Reptiles, including birds, exhibit a range of behaviorally significant adaptations reflected in changes to the structure of the inner ear. These adaptations include capacity for flight and sensitivity to high-frequency sound. We used 3D morphometric analyses of a large sample of extant and extinct reptiles to investigate inner-ear correlates of locomotor ability and hearing acuity. Statistical analyses revealed three vestibular morphotypes, best explained by locomotor categories: quadrupeds, bipeds and simple fliers (including bipedal non-avialan dinosaurs), and high-maneuverability fliers. Troodontids fall with Archaeopteryx among extant low-maneuverability fliers. Analyses of cochlear shape revealed a single instance of elongation, on the stem of Archosauria. We suggest that this transformation coincided with the origin of high-pitched juvenile location, alarm, and hatching-synchronization calls, and adult responses to them.