PrepTest 102, Section 4, Question 15
The southern half of a certain region of(55 more words not shown)
If the statements in the(11 more words not shown)
- ADinosaurs inhabited the(10 more words not shown)
- BPlesiosaurs did not(11 more words not shown)
- CPlesiosaurs did not(11 more words not shown)
- DDinosaurs did not(11 more words not shown)
- EDinosaurs inhabited the(10 more words not shown)
Reading the argument
The location and the time both matter here.
During the Cretaceous period, the southern half of this region was entirely underwater. The passage also tells us dinosaurs lived only on land. So dinosaurs couldn't live in that southern area during that period. We don't need outside knowledge about ancient animals; those are the rules this question gives us.
Could dinosaurs have lived there at another time? Possibly. The passage describes the water coverage during the Cretaceous, not every moment of the longer Mesozoic era. And the swimming plesiosaurs are explicitly excluded from the dinosaur category, so they don't provide an exception to the land-only rule.
What we’re looking for
The question asks what could be true EXCEPT. Four answers need only be possible; one must conflict with the given facts. An answer about a place or period we haven't settled can remain possible. We need a direct contradiction, so keep the southern water coverage, the land-only rule, and the Cretaceous's place within the Mesozoic together.
Working the answers
- A
We haven't been told what happened in the northern half. Dinosaurs could have lived there throughout the Mesozoic. The statement that no single dinosaur species lasted through the entire era doesn't prevent different species from inhabiting that area successively. A doesn't require the same species to be there the whole time.
- B
The southern half was water, so plesiosaurs could have lived there. But a suitable watery location doesn't prove they actually occupied it. They might have lived elsewhere instead. Therefore, their absence from that particular area during the Cretaceous is also possible. B needn't be established; it only needs to remain compatible with the facts.
- C
This is actually required by the passage. Plesiosaurs lived exclusively during the Cretaceous, so they couldn't have occupied the southern half before that period. Something that must be true certainly could be true, which makes it wrong for this EXCEPT task.
- D
Again, we have no information settling dinosaur presence in the northern half. They could have been absent there during the Cretaceous. This doesn't conflict with the fact that dinosaurs existed elsewhere or at other times.
- ECorrect
“Throughout the entire Mesozoic” includes the Cretaceous, its final period. During that part of the era, the southern half was completely underwater and dinosaurs lived only on land. So dinosaurs couldn't inhabit the southern half for the entire era. We have a specific interval that rules out the uninterrupted presence E claims.
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