The question about dinosaurs being endotherms or not have been always a crucial issue among scientists. more specifically the writer put forth the idea that dinosaurs were endotherms. however, the lecturer points out there are some serious flaws in the writer's claim. She more or less addresses the problem with each point made in the reading.
First of all, the writer claims that dinosaur fossils have been discovered in Polar Regions. And only endotherms animals can maintain their body temperature above that of the surrounding environment. But the lecturer refutes whit that point and says that back then polar regions were not this cold and dinosaurs didn't have to maintain their body heat to live there.
secondly, the reading states since there were dinosaurs with legs under their bodies and there is a connection between legs position and physical activities such as running and the physiology of endothermy allows sustained physical activity, then dinosaurs must have been endotherms. But the lecturer believes that supporting dinosaur's heavy body can be the reason for their legs position under their bodies.
Finally, the author wraps up the topic by claiming that the evidence of Haversian canals in fossilized bones of dinosaurs is another reason that proves that dinosaurs were endotherms since bones of endotherms usually include structures called Haversian canals. but again, the lecturer stays on the other side of the argument and says that there were also growth rings in the fossilized bones of dinosaurs that show the slow growth of dinosaurs.
In conclusion, the author and lecturer obviously hold opposing views about dinosaurs being endotherms.