AP Photo

Around 40,000 years ago, the giant kangaroo disappeared from Australia. So did Diprotodon (rhinoceros-size wombats) and Palorchestes (tapirlike marsupials) as well as supersize birds, reptiles and some 50 other so-called megafauna—big animals. And now a record of fungal spores pulled from the swamp at Lynch's Crater in the northeastern corner of the continent reveals humans as the culprit.