TPO综合写作4

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(1-5 TPO4)The lecturer challenges the idea that dinosaurs are endothems favored by the passage.
Firstly, the lecturer contends that the dinosaur fossils found in the polar regions could not be a reason to support that dinosaurs are endotherms. The lecturer gives the following reasons. First, the climate of the polar area was much warmer when the dinosaurs lived so they did not have to be endotherms as the passage maintained. Second, even the climate was as cold as today is, dinosaurs could migratee to warmer places or hibernated like other reptiles do.
Secondly, the fact that dinosaur's legs were under its body not necessarily means that it is evolved for high energy activities. The lecturer gives an alternative explanation. He argues that legs under the body could support more weight which could bring benefits to the dinosaur for growing into large size.
Thirdly, the lecturer also takes issues with the argument that dinosaur had haversian canals in its bone structure which is characteristic of endothermy. Instead, he points out that there were also growth rings in dinosaur's bone structure which were signals of periods that bones won’t grow rapidly. The growth rings showed that during cooler periods, the bone stopped growing or growed at a very slow speed. This phenomenon was not typical of endotherms whose bones grow rapidly even when the climate is cool.
In conclusion, the lecturer completely refutes the three arguments that the author of the passage cited to support his idea that dinosaurs are endotherms. Therefore, based on the evidence provided by the passage, the idea dinosaur was endothermy is unconvincing.