Examkin

Question

Difficulty: MediumNecessary Assumption

Paleontologist: The recently unearthed fossil of *Aerovenator*, a small theropod dinosaur, clearly shows impressions of asymmetrical feathers surrounding its forelimbs. In all modern bird species, asymmetrical feathers are essential for generating the aerodynamic lift required for sustained, powered flight. Therefore, unlike its close evolutionary relatives which were only capable of gliding, *Aerovenator* possessed the ability to engage in sustained, powered flight.

Which of the following are assumptions on which the paleontologist's argument depends? (Select all that apply.)

  1. *Aerovenator* possessed the muscular and skeletal anatomy necessary to utilize its forelimbs to generate aerodynamic lift.Answer
  2. B
    All extinct theropod dinosaurs that possessed asymmetrical feathers were capable of engaging in sustained, powered flight.
  3. The asymmetrical feather impressions preserved alongside the *Aerovenator* fossil did not originate from a different, flying species that was fossilized at the same site.Answer
  4. D
    Sustained, powered flight was the primary evolutionary advantage that allowed *Aerovenator* to outcompete its gliding relatives.
  5. E
    The presence of asymmetrical feathers in modern birds is the direct evolutionary result of their descent from *Aerovenator*.

Answer

The correct answers are the statements that *Aerovenator* possessed the necessary muscular and skeletal anatomy to utilize its forelimbs for lift, and that the asymmetrical feather impressions genuinely belong to the *Aerovenator* fossil rather than another species.
The correct statements represent necessary assumptions because applying the logical Negation Test to them destroys the paleontologist's argument. The argument leaps from the presence of asymmetrical feathers directly to the capability of powered flight. For this leap to be valid, the dinosaur must have possessed all other physiological prerequisites for flight (such as suitable musculature), and the fossil evidence itself must be untainted (the feathers must actually belong to the specimen in question).

Step-by-Step Solution

1
Identify the conclusion and the premises.
Conclusion: *Aerovenator* was capable of sustained, powered flight. Premises: The fossil has asymmetrical feather impressions; modern birds require asymmetrical feathers for powered flight.
Deconstructing the argument is the first critical step to evaluating the logical gap between the evidence and the claim.
2
Identify potential gaps or vulnerabilities in the reasoning.
The argument assumes that having flight feathers is the only requirement for flight, ignoring other physiological needs. It also assumes the physical evidence definitively belongs to this specific dinosaur.
Anticipating logical gaps helps in identifying both 'supporter' and 'defender' assumptions.
3
Apply the Negation Test to candidate answers.
Negating the correct options destroys the conclusion. Negating 'It possessed the necessary anatomy' means it couldn't flap effectively. Negating 'The feathers didn't belong to another species' means there is no evidence *Aerovenator* had the feathers at all.
The Negation Test is the definitive method for confirming whether an assumption is strictly logically necessary.

Key Concept

Necessary Assumption and the Negation Test
Estimated Time:1m 30s
Rate this question

Topics

Necessary Assumption

More questions from this topic