Meeting Abstract
The skulls of many lizards form an open framework of bars and openings, which differ radically from the shell-like, bony skull of mammals. These morphological differences have biomechanical implications. In lizards, strains are generally significantly higher than those of mammals, with less variation between anterior and posterior skull regions. The lightly-built, more flexible skulls of lizards are also supported by more extensive soft tissues than the mammalian skull, such as sheets of fascia over temporal openings, and thick palatal fascia in the oral cavity. Yet, the role of these tissues has been little studied in lizards, despite their likely impact on the strain regime of the skull. For instance, the palatal fascia might allow for the strains to be dissipated from the snout through the palate to the postorbital skull, hence reducing peak strains over the thin bones of the palate. Using the lizard species Salvator merianae and Varanus ornatus as model organisms, we explore the biomechanical significance of these structures by employing 3D computer-based mechanical simulations based on detailed muscle dissections, and in vivo data. First, we simulated muscle activity and joint-reaction forces during biting using Multibody Dynamics Analysis. Next, the forces calculated from these models were used as an input for Finite Element Analysis, to investigate and compare the strains of the skull in these two species. The role of structures, such as the palatal fascia, quadratojugal ligament and post-orbital ligament/bar is investigated and compared between Salvator and Varanus. In a broader context, these results will serve to determine the relative significance of different soft tissues in reptiles versus mammals.
