The reading passage and the lecture are both about whether pterosaurs were capable of powered flight. The author of the reading presents three claims explanations for why pterosaurs couldn't fly. However, the lecturer casts doubt on these claims. She points out serval contradictory recent discoveries.

First of all, the author notes that pterosaurs as cold-blooded animal do not have high metabolism to produce enough energy for powered flight. This point is challenged by the lecturer. She says that recent discoveries of the dense hair like covering of pterosaurs can be a indication of warm-blooded. Since warm-blooded animals typically have high metabolism to keep themselves warm in cold environments. Then the pterosaurs certainly can supply enough energy needed with their high metabolism. 

Secondly, the author states that pterosaurs may be too heavy in weight to fly. This argument is rebutted by the lecturer. She suggests that pterosaurs with their special features can be light in weight even with their enormous sizes. Because the bones of pterosaurs are likely to be hollow instead of solid. Which drastically reduce their weight, and enable them to powered flight even with their big sizes.

Finally, the author mentions that taking off can be an issue for pterosaurs. It is mentioned that with their weight, their weak back leg muscles were not able to allow them take off from powered flights. The lecturer, on the other hand, posits that pterosaurs may not take off in the same way as birds at all. Birds take off and walk by using their two back legs, yet pterosaurs walk, jump, and take off by using four full legs. So these four legs should be definitely enough to enable pterosaurs to take off successfully.