Meeting Abstract
Because they are obligate bipeds that exploit a variety of ecological niches, modern birds experience a great deal of variation in the intensity of the biomechanical stresses experienced by their feet, which, in turn, influences pedal (foot) morphology. Increased pedal grasping capabilities are consistently associated with relative shortening of proximal phalanges, the elements of the foot which are nearest the articulation with the tarsometatarsus. To quantify the relationships between behavior, inferred biomechanical stress, and pedal morphology, we binned modern birds into raptorial, clinging, perching, and ground/water dwelling classifications based on intensity and frequency of grasping behavior and collected morphological data for species in each bin. Using current Avian phylogenic trees, we employed Bayesian statistics to model, for each behavioral bin, the relationships between the length of the penultimate and proximal phalangeals of digits II to IV. We found significant differences in each of the regression models between these four bins and suggest a timeline for the evolution of grasping behavior in modern Aves. In addition, we applied the morphology-behavior relationships observed in modern birds to extinct groups. We measured fossil specimens of Enantiornithines (Mesozoic toothed birds), basal birds, and non-avian theropods in an effort to infer behavior and diet of these lineages during the Mesozoic. With these analyses, we found evidence for evolution of raptorial and perching behavior in Enantiornithines independent from modern Aves. By inferring feeding mode from pedal morphology, we can add depth and detail to our understanding of the predator-prey relationships of the Mesozoic.
