PrepTest 132, Section 2, Question 12
Paleontologist: Plesiosauromorphs were gigantic, long-necked marine reptiles that(47 more words not shown)
Which one of the following(9 more words not shown)
- ABirds and reptiles(11 more words not shown)
- BDuring the age(13 more words not shown)
- CA gigantic marine(30 more words not shown)
- DMost marine animals(11 more words not shown)
- EThe shape of(27 more words not shown)
Reading the argument
Long, thin fins look like long, thin wings. Do they work the same way?
I'm open to the idea that these huge marine reptiles chased prey over long distances. But the paleontologist needs evidence for that hunting style. The evidence offered is a similarity to birds built for long-distance flight. That comparison helps only if fin shape affects swimming in the relevant way that wing shape affects flying. Water and air aren't interchangeable just because two body parts look alike.
What we’re looking for
There's another question too. Even if the fins helped these animals travel long distances, maybe they traveled that way to migrate or breed, rather than to hunt. The argument hasn't settled every issue about their behavior. For the assumption question, though, the comparison gives us a clear place to focus: the paleontologist needs the bird evidence to tell us something about how the reptiles swam.
Working the answers
- A
Shared ancestry isn't required for a comparison about function. The argument could use similarities in how fins and wings work even if those similarities had developed separately. We need the physical comparison to be relevant, not a particular account of its evolutionary origin.
- B
Why must these reptiles be unique? Other marine reptiles could also have had long, thin fins without undermining the argument about this species. Exclusivity contributes nothing essential to the comparison with birds.
- C
This would give us a strong additional reason to expect long-distance hunting: the animals supposedly couldn't get enough food any other way. But the argument doesn't need that claim. They could have been able to meet their food needs by ambushing prey and still have chosen or evolved to hunt by chasing it.
The question asks what the reasoning depends on. A new route to supporting the conclusion isn't automatically a requirement of the route actually used.
- D
This makes a claim about most marine animals that chase prey over long distances. The argument concerns these reptiles and the evidence supplied by their fins. Other animals could swim long distances without specialized bodies, and that wouldn't by itself destroy the proposed comparison here.
- ECorrect
Fin shape must affect swimming in the same relevant way that wing shape affects flight for the bird comparison to support this conclusion. Otherwise, long, thin bird wings could tell us nothing about what long, thin reptile fins allowed their owners to do.
Try removing that connection: similar shapes could have different effects in water and air. The paleontologist would then lose the evidence offered for long-distance hunting. That is why this assumption matters to the argument.
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