PrepTest 142, Section 4, Question 4
Paleontologists had long supposed that the dinosaur Diplodocus(68 more words not shown)
Which one of the following(7 more words not shown)
- AThe same type(9 more words not shown)
- BDiplodocus was not(14 more words not shown)
- CIt would be(15 more words not shown)
- DDiplodocus had no(15 more words not shown)
- EDiplodocus was not(17 more words not shown)
Reading the argument
A long neck makes reaching high leaves sound plausible. But perhaps the neck served some other purpose, such as attracting a mate. Its length alone doesn't settle what the dinosaur ate.
Let's accept the computer models: Diplodocus couldn't raise its neck in the way paleontologists had imagined. It could lower its head, even reaching underwater plants while standing on dry land. I can picture the dinosaur beside a lake, dipping its head down to feed.
Being able to do that isn't a record of an actual meal. Still, read the conclusion carefully: it allows plants on the ground, near the ground, or underwater. Eating grass would fit this conclusion; we shouldn't object as though the author had insisted on underwater feeding alone.
What we’re looking for
We're looking for something the argument needs in order to restrict feeding to those low locations. The useful question is whether the facts about the neck really justify that restriction. Keep that question open as we consider the choices.
Working the answers
- A
Modern animals don't have to share this neck structure. Diplodocus could have fed near the ground even if its particular structure disappeared with the dinosaurs. The argument concerns what this animal could reach, not whether that anatomy survives today.
- B
We don't need a limitation on its vision. Diplodocus might have been able to see straight ahead while still feeding on low plants. Whether its head had to angle downward to see isn't a condition the reasoning requires.
- C
The argument already gives a structural reason its neck couldn't rise as imagined. It doesn't also need a separate claim about blood flow. Perhaps its circulatory system could have supplied an elevated brain even though its neck bones prevented that particular movement.
- DCorrect
What if it stood on its hind legs? That could raise the whole animal and bring high leaves within reach without the neck bending upward in the prohibited way.
Now we can see what the argument assumes: ruling out one way of reaching high vegetation rules out high vegetation altogether. To support that restriction, it needs to exclude other ways of reaching those plants. D supplies that requirement. If another route were available, the neck model would no longer justify limiting the dinosaur to low or underwater food.
- E
Kneeling beside water or walking into it would be additional ways to obtain underwater plants. Those possibilities fit the conclusion rather than threaten it. The author doesn't need standing on dry land to be the dinosaur's only way of feeding underwater.
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