According to the reading passage, the author claims that large pterosaurs were incapable of powered flight. The professor, however, holds the opposed viewpoint because of three reasons.
  Firstly, the reading passage points out that ancient reptiles such as pterosaurs were probably cold blooded and were incapable of producing enough energy to fly. But the professor disagree with it because pterosaurs have a dense, feathers covering which was typical of warm blooded animals whose metabolism was able to supply the energy require for powered flight.
  Secondly, the reading passage expressed that pterosaurs were too heavy to stay aloft for any length of time. But the professor give the opposite viewpoint that the bones of pterosaurs were hollow instead of solid. So, although they had large body frames, the pterosaurs' weight was low enough to allow them to keep themselves in to the air by flapping wings.
  Thirdly, the author states that pterosaurs were lack in muscles to run fast enough or jump high enough to launch themselves into the sky. The professor disagree with it because the