Macropus rufus, Red Kangaroo skull

cults3d

Marsupial herbivores display a diverse array of skull shapes and sizes in order to exploit different ecological niches effectively. Research on teeth, dentaries, and jaw adductor muscles reveals that marsupial herbivores exhibit distinct specializations for grazing and browsing. Despite this, no studies have yet examined the skulls of marsupial herbivores to establish a connection between stress and strain, and the evolution of skull shape. A relationship was tested between skull morphology, biomechanical performance, and diet by applying the finite element method to the skulls of four marsupial herbivores: the common wombat (Vombatus ursinus), koala (Phascolarctos cinereus), swamp wallaby (Wallabia bicolor), and red kangaroo (Macropus rufus). It was predicted that grazers, requiring stronger skulls to process tougher food, would possess higher biomechanical performance than browsers. This prediction held true when comparing the koala and wallaby (browsers) to the wombat (a grazer). The cranial model of the wombat produced low stress and high mechanical efficiency relative to a robust skull capable of generating high bite forces. However, the kangaroo, also a grazer, has evolved a different strategy to process tough food. The cranium is much more gracile and experiences higher stress and lower mechanical efficiency, but they employ a different method of processing food by having a curved tooth row to concentrate force in a smaller area and molar progression to remove worn teeth from the tooth row. Therefore, the position of the bite plays a crucial role in the structural performance of the kangaroo skull, whereas it does not for the wombat which processes food along the entire tooth row. In agreement with previous studies, the results from this study confirm that the mammalian skull is optimized to resist forces generated during feeding. However, other factors, including the lifestyle of the animal and its environment, also influence selection for skull morphology to meet multiple functional demands.