task1task2 E rater Both the reading passage and the lecture discuss the possible explanations of mass extinction in the Triassic period The passage proposes three explanations to account this phenomenon However the professor in the lecture casts doubt on

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Both the reading passage and the lecture discuss the possible explanations of mass extinction in the Triassic period. The passage proposes three explanations to account this phenomenon. However, the professor in the lecture casts doubt on all the explanations mentioned in the passage.

First of all, the passage states that the decline of sea levels could be the cause of the mass extinctions, since the fluctuation of the sea levels could destroyed the habitats for ocean populations. Nevertheless, the professor counters the passage by arguing that species that live in the costal ecosystem are good at adapting the fluctuation of sea levels. Moreover, the decline of sea levels happened gradually, yet only sudden decline was able to cause mass extinction.

Secondly, the passage claims that massive climate cooling could be the reason for mass extinctions, since the Triassic period was marked by widespread volcanic activity, and volcanoes released large amounts of sulfur dioxide, which is known to cause a lowering in global temperatures. Notwithstanding, the professor disagrees with the passage. Since sulfur dioxide clear out quickly from the atmosphere, it is unlikely that sulfur dioxide could stay long enough to cause massive climate cooling.

Finally, the passage mentions that asteroid strike is the candidate that caused mass extinctions. Since the collision from asteroid could displace large amounts of soil and crushed rock, those displaced debris can block out sunlight for a long time. However, the professor refutes the passage by pointing out that most of craters found by scientists were formed two to three million earlier than the mass extinction. Thus, asteroid strike cannot be the convincing reason.
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At the end of the Triassic period 200 million years ago, there was a mass-extinction event that caused the extinction of more than half of all living species. It was this extinction event that allowed dinosaurs to become the dominant species for the next 145 million years. We do not know exactly what happened that eliminated so many species in a relatively short period of time, but there are several possible explanations.

One theory involves the decline of sea levels. Near the end of the Triassic period, sea levels were fluctuating. When sea levels fall, the habitats for ocean populations that live in the shallows and land species that live on the coast are destroyed. The destruction of coastal and shallow-ocean species would have had a profound effect on food chains worldwide, leading to mass extinctions.

Another theory involves massive climate cooling. The end of the Triassic period was marked by widespread volcanic activity. The volcanoes released large amounts of sulfur dioxide (SO2). A rise in atmospheric SO2 is known to cause a lowering in global temperatures. Such climate change could have devastated many species and led to the extinctions.

The third theory involves an asteroid strike. Asteroids (objects from outer space) occasionally collide with Earth. When an asteroid hits Earth’s surface, it often displaces large amounts of soil and crushed rock, leaving behind a depression, or crater. The displaced debris is thrown up into the atmosphere where it can block out sunlight for many months or even a few years. A sufficiently massive asteroid impact at the end of the Triassic period may have blocked sunlight long enough for most plants to die and many animal species to then starve.