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For much of the 20th century, paleontologists theorized that dinosaurs, like reptiles, were ectothermic, their body temperature regulated externally. These scientists, however, based their conclusions on faulty reasoning, claiming that scaly skin was common to all ectotherms (birds, which are ectothermic, do not have scaly skin) and that the dinosaur’s size could account for ectothermy (some adult dinosaurs weighed as little as ten pounds). Supplanting this theory is an entirely new line of thought: dinosaurs were actually mesothermic, neither warm- nor cold-blooded. By taking this middle ground, some paleontologists maintain that dinosaurs were faster than a similar-sized reptile yet did not require as much food as a similar-sized mammal. To substantiate this theory, paleontologists intend to study how birds, the dinosaur’s closest extant relative, might have at one time been mesothermic.
Which of the following does the passage imply regarding birds?
Title
Mesothermy
Your Result
Correct
Difficulty
Medium
Your Pace
0:01
Others' Pace
1:42
Video Explanation
Text Explanation
The passage mentions that some scientists claimed that all ectotherms have scaly skin, However, according to this faulty reasoning, birds, which are ectotherms, do not have scaly skin. Therefore, they have certain features that they do not share with other ectotherms, i.e., the lack of scaly skin. Answer: [A].
The passage mentions that dinosaurs require less food than a similar-sized mammal. However, there is no mention about how much food a bird requires. Sure, birds, like dinosaurs, might have been mesothermic, but mesothermy relates to body temperature regulation, not to the amount of food consumed.
The last sentence states that birds “might have at one time been mesothermic.” That is, they might have changed from mesotherms to ectotherms. From the first sentence, we learn that "ectothermic" describes body regulation. Therefore, birds possibly changed the way they regulate body temperate. Answer [C].
Frequently Asked Questions:
FAQ: The passage states that the fact that "scaly skin is common to all ectotherms" is based on faulty reasoning. So, how is (A) be correct?
A: This is the path of logic that we can take to address this:
- Birds are ectotherms
- Birds do not have scaly skin, but other ectotherms do
- Therefore, birds have traits (lack of scaly skin) that are not common to all ectotherms. In other words, other ectotherms have a trait that birds do not have.
What is based on faulty reasoning is the idea that all ectotherms have scaly skin. This isn't true: birds do not have scaly skin, but are ectotherms. Therefore, birds possess certain traits that are not common to all ectotherms, which is what (A) states. =D
Related Lessons
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