Integrated essay about Endotherms from the book of (ETS official TOEFL iBT TESTS)

The lecture casts doubt on the passage's points about the dinosaurs to be endotherms.

Firstly it denies the point about the fossil found in the polar region to be the prove for dinosaurs to be endotherms.As the polar region was warmer than today.So they not necessarily to be endotherms to change their body temperature according to the environment.In addition to that the lecture states migration as the possible reason for the fossils found in the polar regions.

Secondly,it states that legs under the body is not an evidence of being endotherm, as dinosaurs were big in size, so it was itself an advantage for them and the major point is it supports a big size body.So it doesn't prove that it helped them to be high energy animal to run faster.Hence it's not an evidence that dinosaurs are endotherms.

Third and final point is that though presence of havernesian canal is true for endotherms, yet it does not prove that dinosaurs are endotherms.As dinosaurs had growth rings which shows the period of time.In contrast to the passage, the lecturer's opinion is that the growth rings show rapid growth followed by no growth or slow growth, which is not true for endotherms.