TPO 39 integrated writing skill

According to the reading passage, author lists three explanations to show why there was a mass-extinction in Triassic period 200 million years ago. However, speaker holds opposite ideas and states that none of the passage's arguments were good explanations, also, she mentioned other competing theories that contradict passage's ideas.
At first, the essay assumes that decline of sea levels probably caused destruction of shallow-ocean and land species that lived on the coast. While, writer supposes that although sea levels was fluctuating, but coastal species and shallow-ocean animals were able to adapt, so, changes should have to be much more sudden to affect those species.
Second, author indicates that massive climate cooling due to volcanic activity in Triassic period is another theory, because released large amounts of sulfur dioxide caused a lowering in global temperatures. In contrast, lecturer points out that sulfur dioxide already existed in atmosphere and even it combined with water, thus stationary existed SO2 did not affect seriously.
Finally, the essay discusses that asteroid strike often displace large amount of soil and crushed rock, leaving behind a depression, or crater. Contrarily, speaker admits that although we find crater, but it belongs to 12 million years before the mass-extinction, thus it was too long ago to cause the mass-extinction
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