Meeting Abstract
Movement among intracranial joints, cranial kinesis, is a fundamental function of the feeding apparatus of parrots. The skulls of parrots possess a mobile quadrate which drives movement of the mandible, palate, and rostrum. These kinetic movements are facilitated by a mixture of joint tissues at the otic, palatobasal, palatomaxillary, and craniofacial joints of the skull. Because of the anatomical similarity of the feeding apparatus, the soft and bony tissues of the linkage system are hypothesized to mitigate stresses and strains associated with feeding in similar patterns across parrots despite disparate dietary niches. Here we test this hypothesis in taxa exhibiting diverse dietary regimens by mapping stress and strain propagations within the skull and across joints. Using the BoneLoad workflow, jaw muscle forces were estimated using volumetric properties and bite forces estimated using 3D lever mechanics. Finite element models were loaded using flexible joints with anatomically accurate sutural material properties and anatomically informed constraints. Estimated bite forces were then applied to homologous points of the maxilla across all four taxa to generate a simulated load on the feeding apparatus. Resulting mechanical properties were qualitatively analyzed across the skull. Regions of interest were sampled in the pterygoid, palatine, and quadrate bones to quantitatively compare models. Our results indicate that feeding-generated forces and strains about kinetic joints are similar among the sampled parrots. This suggests dietary preferences of parrots may be better reflected by their feeding behaviors and other features such as beak shape, or tongues. Regardless, the kinetic linkage remains an innovation underlying parrot feeding behavior and new details will improve future ecomorphological and evolutionary hypotheses in extant and extinct kinetic birds and archosaurs.
