Student or Learner
The lecture talks differently from the reading in that it defies the reasons the reading uses to support the idea that dinosaurs are endotherms. It does not agree that the region dinosaurs used to live, their leg position and their bone structure can demonstrate that they are endotherms.
To begin with, dinosaurs did live in Polar Regions but they didn't have to develop a system to sustain constant body temperature as stated in the reading. In fact, those areas were much warmer during the time when dinosaurs lived there, according to lecture. Even though there were periods that were cold, dinosaurs can also migrate or hibernate to escape that cold.
Then, the evidence cited in the reading that legs are under dinosaurs' bodies like other endotherms doesn't suffice to show they are one of them. Because endotherms basically use that leg position to maintain the effectiveness when running, whereas dinosaurs, as said in the lecture used their legs to support their unprecedented body weight, which is only possible when legs are under their bodies.
In the third place, bone structure, which was used in the reading as another evidence, can also be cited to show the just opposite. Bones of dinosaur do not only contain Haversian, but their growth rings uncover the truth that they did not grow fast all over the year. They actually had to lower their growth speed to adapt to the cold weather like reptiles.
THANKS,Gil! I've learnt a lot.