tpo39

The reading and the listening passage have a debate on factors which are responsible for mass-extinction at the end of the Triassic time. The writer puts forward 3 main points which are refuted by following speaker.

First, the writer suggests that sea levels were decreased and shallow ocean creatures were died; as a result, shortage of food in coastal areas leaded to extinction. The speaker views this issue from opposite angle. According to her, coastal fluctuation was gradual. For decreasing the mass population in Triassic period, this chenge in sea levels should happen sudden. Thus, it is not advisable that reducing sea levels take part in that extinction.

The second reason offered by the writer is weather cooling because of volcanic activity. Huge amount of SO2 led to reducing in world temperatures which consequently damages to living species. The speaker casts doubt on this assumption by saying that excess SO2 in the air in the present of water could clear and return to the earth as acidic rains. So, the short period of abound SO2 could not produce such problem.

Last, the writer proposes that asteroid strike may result large amount of dust and prevent receiving sunlight to earth. This event destroyed plants and made trouble for other species. On contrary, the speaker holds an opposite view. She claims that very few scientist believes asteroid strike and they could not find asteroid creature. In addition, this event happene 12 million years before mass extinction. Furthermore, it can not be related to this matter.