The researchers in the argument argue that at least some dinosaurs might have been warm-blooded. It is very important to note that this is a cause and effect argument.
The observed effect that these researchers are trying to explain is the discovery of dinosaur fossils in the northern arctic. The proposed cause is that at least some dinosaurs might have been warm-blooded because only warm-blooded animals could have withstood the frigid temperatures that are characteristic of arctic winters, whereas cold-blooded animals would have frozen to death in such extreme cold.
Remember that there are three ways to weaken a cause and effect argument: (1) alternate cause, (2) cause without effect, or (3) effect without cause.
(A) is incorrect because information about today's reptiles will not help us weaken the researchers claim that some dinosaurs might have been warm-blooded. Notice that, if anything, (A) seems to strengthen the researcher's argument that at least some dinosaurs might have been warm-blooded because even today, cold-blooded animals are generally confined to regions of temperate or even tropical climates (i.e. cold-blooded animals cannot survive in extreme cold).
(B) is incorrect because size is irrelevant to the discussion of cold-blooded animals being able to survive arctic winters.
(C) is incorrect because, if anything, it helps to strengthen the claim made by the researchers. If the arctic dinosaur fossils were found alongside fossils of plants known for their ability to withstand extremely cold temperatures, it strengthens the researchers' argument by helping to establish that arctic winters during the time of the dinosaurs were also extremely cold.
(D) is CORRECT because it presents an alternate cause that weakens the researchers' argument. The reason we have discovered dinosaur fossils in the northern arctic is not because some dinosaurs might have been warm-blooded, but rather because these dinosaurs were migrating in search of a continual food supply. Notice that with this evidence, the discovery of dinosaur fossils in the northern arctic is entirely consistent with dinosaurs being cold-blooded because these dinosaurs could have migrated to the northern arctic in search of food and died there because they were unable to withstand the arctic winter.
(E) is incorrect because it does not help us weaken the researchers claim about arctic dinosaurs being warm-blooded. It actually strengthens their argument by eliminating the possibility that arctic winters may not have been as cold as they are today, which would have given cold-blooded animals a chance of survival. The experts remove all doubt that the arctic winters have stayed the same, meaning only warm-blooded animals could have survived them.
Hope that was helpful! Please let us know if you have any other questions.
BatmanNovember 14, 2013
Many thanks!!! I was curious how the herds of it that have cold blood immigrate to extremely cold weather region even if they need to find food. But now I understand I need to tackle the point within the stimulus, not in my thoughts or knowledge. Thanks again!!!
