Some researchers have speculated that the replacement of nutritious, fire-sensitive plants with less flammable, less nutritious flora brought about by human, fire-based deforestation in Australia played a large role in "P. goliah" and other Australian megafaunal extinctions about 50 thousand years ago (kya). However, the diet of "P. goliah", primarily chenopods and "Atriplex" in particular, were less flammable and remained largely unaffected by fire. These diet patterns disprove theories that "P. goliah"'s extinction was due in large part to a reduction in food supply from fire. At the same time, because of the kangaroos' elongated breeding cycles, their ability to increase population numbers after human predation was highly limited.