Marco: Giant kangaroos - one of several extinct species of mammals (megafauna) - went extinct around 46,000 years ago. The deposits and wear patterns on the teeth of these animals from around the time of their extinction indicate that they fed mostly on saltbrush and shrubs. Saltbrush thrives in arid climates, so it is not likely that the kangaroos' food supply was adversely affected by the increasing aridity of the climate at that time. Thus, something else would have to account for their extinction, and the best candidate for that cause is predation by humans.
Fatima: That argument alone is not likely to satisfy many researchers in this filed. Have you found any other evidence to bolster your conclusion?
A. Giant kangaroos became extinct during a period that was less arid than previous periods they endured.
B. Many researchers believe humans first arrived in Australia around 40,000 years ago.
C. Approximately 60 different species in Australia died out in the wave of extinctions around 46,000 years ago.
D. Fossils of giant kangaroos also sho evidence that those animals' diets routinely included plants other than saltbrush.
E. Several types of megafauna larger than the giant kangaroo went extinct around 46,000 years ago.