The reading and the lecture are both about whether dinosaurs were endotherms. While the author of the article argues that there are three possible reasons for support that dinosaurs were endotherms, the lecturer disputes the arguments made in the article. His position is that the theories do not prove that dinosaurs were endotherms.
According to the reading, fossils have been discovered in Polar regions. The article mentions that this fact supports that dinosaurs lived in cooler zones. Thus, dinosaurs should maintain their internal temperature well above that of the surrounding environment. This specific argument is challenged by the lecturer. She claims that actual polar regions were warmer zones as a result dinosaurs did not need to be endotherms in order to live in these zones. Additionally, she points out that when the temperature in polar regions increased. Dinosaurs migrated to other warmer zones. Consequently, this argument does not support the idea of dinosaurs as endotherms.
Secondly, the author claims a connection between the endothermy and the position and movement of the legs. Since the dinosaur's leg is positioned underneath its body this fact allowed it to be able to do sustained physical activities, such as running. This fact suggests that dinosaurs were endotherms. The lecturer, however, asserts that the reason for the position of dinosaur’s legs does mean that they were endothermic. She goes on to say that the dinosaur's leg position allowed it to support more weight. Consequently, they could grow to a very large size.
Finally, the author puts forth the idea that there is a connection between endothermy and bone structure. The author contends that dinosaurs had Haversian canals in their bones. These canals allow the animal to grow quickly, and a rapid body is a characteristic of endothermy. In contrast, the lecture said dinosaur's bones also had growth rings. Growth rings indicate a period of times where dinosaurs were not rapidly growing. She notes that these growth rings show that dinosaurs stopped growing or grew more slowly in cooler environments. Thus, dinosaurs were not endotherms since endotherms grow quickly even if their environment is cooler.