▶ Your Answer :
In the lecture, the professor refutes three theories on the extinction of Diprotodon presented in the reading.
First, he describes that the first theory, which explains that the extinction of Diprotodon is due to its low reproductive rate, has a hole. He uses an example of Koala bears, which produce less offsprings than Diprotodon over the course of its life. This casts a doubt on the reading passage that Diprotodon became extinct because it produced too few young to sustain itself.
Second, the speaker disproves the second theory, which finds the cause of Diprotodonn's extinction from a sudden and severe shortage of food. He explains that in fact, fire set up by early humans didn't eliminate Diprotodon's primary food, but made the land fertile. In addition, he says that Diproton had alternative foods to eat when saltbush was scarce, so it is doubtful to theorize that Diprotodon extincted due to the lack of food.
Third, the lecturer rejects the theory that Diprotodon was killed of by predators. While the article describes Diprotodon as a peaceful herbivore, which can't move quickly or hide easily due to its enormous size, he states that only few predators would had been able to prey on Diprotodon due to its hugeness. He also argues that if Diprotodon was an easy prey for other predators, it should died off much earlier.
For these reasons, the professor disagrees with the three theories proposed in the article. |