Meeting Abstract
Although many species of vertebrates evolved feeding behaviors that employ cranial kinesis, little is known about the loading environment of the palate and other parts of the suspensory apparatus responsible for this movement. Additionally, the role protractor muscles play in controlling palatal excursion or insulating the braincase and sensory capsules via palatocranial joints is challenging to test in vivo and equally unclear. We explored the morphology of jaw musculature, kinetic joints and cranial bones using diffusible iodine-contrast CT and histology of Varanus exanethematicus, a modestly kinetic anguimorph lepidosaur. DiceCT imaging and fiber tracking analysis shed new light on the muscular anatomy and architecture of these muscles. Finite Element Modeling was employed to test the effects of muscle activation and joint material properties on the loading environment of the palate, braincase, and skull. We found different joint material properties have only minor effects on the loading environment of the skull. Complex interactions between m. levator pterygoideus and m. protractor pterygoideus work to stabilize the palate about the palatocranial joints and ultimately diminish the strains experiences by the braincase. The tubular cross-section and second moment properties of the pterygoid bone reflect l the bending and torsional environment developed during biting. These data will inform future studies of cranial function and illustrate how morphological complexity of cranial bones, joints, and muscles evolve in different lineage of lepidosaurs and reptiles in general. New understanding of the biomechanics of the jaw muscles, bony linkages and connecting joints reveals a better understanding of skeletal adaptation, physiology and evolution.
