Food webs play important roles in hypotheses relating to Pleistocene vertebrate evolution, such as megafauna evolution, insular dwarfism and gigantism, and Late Pleistocene extinctions. However, food webs reconstructions of Australasian Pleistocene fauna have been hindered by the lack of suitable trophic level proxies. This thesis aimed to improve our understanding of food webs of Pleistocene Australian megafauna and island fauna from Flores (Indonesia) through calcium (Ca) and strontium (Sr) isotope geochemistry.