TOEFL Sample essay : integrated essay from TPO4

The reading passage asserts that dinosaurs differ from modern reptiles and are endothermic. It also brings up three reasons to support this. However, the lecturer finds all the ideas dubious. She claims that scientists have problem with the arguments mentioned in the passage and presents some evidence to refute them all.

First, the author of the passage takes the polar dinosaurs to prove that these animals were endotherms since they lived in a cold region where only warm-blooded animals could live there. In contrast, the speaker disproves this idea and explains that pole’s weather was warm enough for animals that were not endotherms to live there during the period that dinosaurs lived. In addition, the non-warm-blooded animals could have migrated or hibernated during cold months, the same as modern reptiles. The speaker deduces that polar dinosaurs mentioned in the passage weren't the reason to prove that they were endotherms.

Second, it is mentioned in the article that the analogy of leg position in dinosaurs and modern endotherms strongly shows that dinosaurs were endotherms. Conversely, the lecturer rejects the idea by bringing up a logical reason that the legs located underneath its body were not necessarily used for running. She states that the position of the legs helped the animal to bear more weight. Therefore, this body structure made the dinosaurs could grow a very large size. The lecturer draws conclusion that this body structure and being large have some advantages that there is no need to run.

Finally, the reading passage claims that dinosaurs are endotherms since the Haversian canals have been found in fossilized bones of dinosaurs which allow the endothermic animals to grow quickly. On the contrary, the professor disagrees with the idea that dinosaurs were endotherms. She pinpoints the fact that the bone structure found in fossils is true but the growth rings were found in the fossils as well. The growth rings show the velocity of thickening of the bone. The evidence found in fossilized bones of dinosaurs expose several growth periods including both rapid and slow growth. They disclose that they stopped growing during cold periods. Therefore, the speaker concludes that dinosaurs weren't endotherms because the endothermic animals grow rapidly even the weather becomes cold.