Endotherms are animals such as modern birds and mammals that keep their body temperatures constant For instance humans are endotherms and maintain an internal temperature of 37 C no matter whether the environment is warm or cold Because dinosaurs were

Both the reading and the lecture discusses whether dinosaurs were endotherms or not. The author of the reading passage argues that dinosaurs were endotherms—animals that can maintain body temperature—and provides three supporting reasons, but the professor challenges each of these points.
First of all, the writer contents that dinosaurs were endotherms because fossils of them were found in the polar region lately which implies that they lived there a long time back and could have survived cold weather only by maintaining body temperature, that only endotherms can do. However, the lecturer challenges this reasoning and says that polar regions were much warmer in the past than they are now and thus dinosaurs could have survived there without the need of maintaining body temperature. She even goes to say that even if it were too cold in winter, the dinosaurs could have just migrated to warmer a place and returned to polar region later.
Secondly, the author of the reading passage asserts that presence of legs underneath, rather than on the sides, of bodies of dinosaurs implies that they were endotherms. In contrast, the professor challenges this supporting reason and says that they had legs on sides in order to support more body mass. According to the professor, having higher body mass was advantageous, and it could only be supported by having legs on sides.
Finally, the author claims that the presence of Haversian canals in the bone structure of dinosaurs suggests that they were endotherms. Nevertheless, like the two reasons above, the professors rebuts the point too and says that dinosaurs also had growth rings which the writer failed to acknowledge. Presence of growth rings means that dinosaur’s growth, unlike growth of endotherms, was not steady, but had alternating periods of high growth and low growth.