In an attempt to explain the development of toucans’ characteristic bills, the author presents three plausible theories, which are critically reevaluated in the lecture.
First of all, the writer mentions the destructive function of toucans’ bills. In the author’s perspective, the big bills could have been used to damage the predators while protecting toucan themselves. On the other hand, the professor casts doubt on such argument presented in the reading passage, since bills are too vulnerable to surroundings. To be specific, the professor mentions that the light and airy qualities of bills would have made them easily damaged during the fight.
Furthermore, the author claims that the bills could have been used to camouflage toucans in the deep forests. Since the colors of tropical environment and toucans’ bills match perfectly, toucans could have utilized the bills to hide themselves. Nevertheless, the instructor believes that toucans have no need to camouflage. Indeed, toucans always flock together, making loud noises, quite identifiable to their enemies.
Last but not least, the writer argues that the bills enable toucans to lose their temperature by effectively pumping blood. However, the lecturer rebuts the author's idea by suggesting that toucans cannot (cannot보다는 should not이 의미상 더 맞을 것 같아요) lose their temperature due to cold nights in the tropical areas because losing temperature through bills can possibly be lethal to toucans.
In short, the author and the professor have contradictory opinions concerning the theories on the development of toucans’ bills.
전반적으로 author의 point of view와 lecturer의 point of view가 잘 비교되고 있는 것 같아요. 하지만 문장간의 transition에 조금 더 신경 써 주시는 게 좋을 것 같아요.