LR Drill Set 9, Question 11
Dromaeosaurs, which date to about the time of(61 more words not shown)
The statements above, if true,(10 more words not shown)
- ADromaeosaurs were(1 more words not shown)
- BSome flying dinosaurs(4 more words not shown)
- CDromaeosaurs were ancestors(3 more words not shown)
- DDromaeosaurs were(1 more words not shown)
- EMost dinosaurs were(1 more words not shown)
Reading the argument
Feathers don't have to mean flight. A flightless bird can still use them to retain body heat.
That helps us understand why the passage mentions feathers on dromaeosaurs even though their forelimbs were too short for flight. The feathers could have served another purpose. The passage gives us a temperature explanation: feathers retain heat in warm-blooded animals, while cold-blooded animals need to absorb heat and therefore cannot have feathers under the rule we're given.
Now put that rule beside the fossils. The fossils indicate feathers, and feathers rule out being cold-blooded. Within the warm-blooded/cold-blooded distinction the passage uses, that points to dromaeosaurs being warm-blooded.
What we’re looking for
The question asks what the information supports. Follow the connection between the feathers and temperature regulation; that is the information we can actually use.
Working the answers
- A
This conflicts with the combination of facts we're given. Dromaeosaurs apparently had feathers, and cold-blooded animals cannot have feathers under the stated rule. Their inability to fly doesn't make them cold-blooded; flight and temperature regulation are different matters.
- B
We aren't given information establishing a group of flying dinosaurs without feathers. The dinosaurs discussed here could not fly and apparently did have feathers. We cannot use this example to establish both of the different traits B describes.
- C
Being around at about the time of the earliest birds does not establish ancestry. Dromaeosaurs could share feathers with birds without being their ancestors. We'd need evidence connecting the groups through descent, which the passage doesn't provide.
- DCorrect
The apparent feathers are the key. According to the passage, cold-blooded animals cannot have them because feathers would interfere with the heat absorption those animals need. Dromaeosaurs therefore fit the warm-blooded side of the distinction.
This also gives the feathers a useful role even without flight: retaining body heat. The conclusion follows the evidence about temperature regulation rather than assuming that any animal with feathers must be able to fly.
- E
We have information about dromaeosaurs, not a count of how many dinosaurs were cold-blooded. Even if this evidence settles how to classify dromaeosaurs, it doesn't tell us whether they were typical or unusual among dinosaurs. A conclusion about most dinosaurs needs a much broader basis.
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