The reading mainly presents that there are three theories why many species eliminated in a relatively short period of time. However, the lecturer challenges what are stated in the passage by providing three strong evidences.
Firstly, in the reading, the decline of sea levels is factor that many species eliminated in a relatively short period of time. In contrast, the lecturer holds an opposing view, saying that the fluctuation of sea level allow species to adapt gradually to environment change. Also, the fluctuation of sea level appear suddenly rather it change slowly and take a lot of time.
Secondly, the passage asserts that massive climate cooling lead to mass extinction s because the volcanoes released SO2 that cause a lowering in global temperature.However, the professor also maintain the it is true that the volcanoes release large amount of sulfur dioxide such as SO2. However, SO2 disappear quickly because SO2 combine with water in cloud and rain included SO2 fall out of ground. For this reason, SO2 do not stay a long time in atmosphere.
Finally, the author of the reading passage believe that an asteroid strike is sufficiently evident that many species eliminated in relatively short of time. On the other hand, the lecturer disagrees in with the point that few researchers believe an asteroid strike theory supporting an evident such as craters does not find anywhere. Other researchers find a crater and it created before species extinction. For this reasons, an asteroid strike theory is not sufficiently an evident.