Australian megafauna died out due to climate change. Humans did not help, but they were already on the way out due to food shortages.
Mounting evidence points to the loss of most species before the peopling of Sahul (circa 50–45 ka) and a significant role for climate change in the disappearance of the continent’s megafauna.
A study of the fossil teeth of megafauna from Cuddie Springs in NSW suggests that climate change had a significant impact on the diets of these giant animals and may well have been a primary factor in their extinction.
Australian megafauna died out due to climate change. Humans did not help, but they were already on the way out due to food shortages.
https://www.pnas.org/doi/10.1073/pnas.1302698110
https://www.unsw.edu.au/newsroom/news/2017/01/climate-change-helped-kill-off-super-sized-ice-age-animals-in-au