Ornithologist: The curvature of the claws of modem tree-dwelling birds

Question

Ornithologist: The curvature of the claws of modem tree-dwelling birds enables them to perch in trees. The claws of Archeopteryx, the earliest known birdlike creature, show
similar curvature that must have enabled the creature to perch on tree limbs. Therefore, Archeopteryx was probably a tree‑dwelling creature.

Paleontologist: No, the ability to perch in trees is not good evidence that Archeopteryx was a tree‑dwelling bird. Chickens also spend time perched in trees, yet chickens are primarily ground‑dwelling.

Which one of the following is an assumption on which the ornithologist’s reasoning depends?

(A) Modem tree‑dwelling birds are the direct descendants of Archeopteryx.

(B) Archeopteryx made use of the curvature of its claws.

(C) There have never been tree‑dwelling birds without curved claws.

(D) Archeopteryx was in fact the earliest birdlike creature.

(E) The curvature of the claws is the only available evidence for the claim that Archeopteryx was tree‑dwelling.

sudarshan22 · Answer

+1 for   B  .

Stimulus   :
Archaeopteryx was tree-dwelling, and was involved perching in trees by making use of the curvature of its claws.

(B) Archeopteryx  made use of the curvature of its claws . -->  Correct, Negate the statement and see how it affects the conclusion

Hence,   B  .

lfc · Answer

Hi,

A) No such relationship is mentioned.
B)  Correct  If you negate this assumption, the ornithologist’s argument falls apart.
C) The ornithologist’s argument says that the curved claws enabled the Archeopteryx to sit on trees, this option uses the reverse logic. You can also use the negation test to see that even if there are tree dwelling birds with curved claws, the argument still stands.
D) Does not make a difference to the reasoning.
E) Does not make a difference to the reasoning.

Jatinjhalani · Answer

Approach - 
1) Eliminate A --> out of scope
2) Negating B --> destroys the argument. Therefore, B is correct
3) Eliminate C --> doesn't exclude the possibility that "not tree dwelling but have curved claws"
4) Eliminate D --> out of scope
5) Eliminate E --> negating implies something else other than curved claws can also lead to tree dwelling.

Maha Lina · Answer

A. Modern tree-dwelling birds are the direct descendants of Archeopteryx. This statement gives no relationship to the conclusion
B. Archeopteryx made use of the curvature of its claws. The negation is that Archeopteryx did not use the curvature of its claws -> thus breaking the conclusion (correct option).
C. The negation of the statement "There have never been tree-dwelling birds without curved claws" is "There have been tree-dwelling birds without curved claws." which does not break the conclusion.
D. Archeopteryx was the earliest birdlike creature. This statement gives no relationship to conclusion
E. The curvature of the claws is the only available evidence for the claim that Archeopteryx was tree-dwelling. This assumption ignores other potential evidence that could refute the claim, such as chickens with claws but living on the ground. Therefore, it is not a logically valid assumption to consider the curvature of the claws as the sole evidence for the tree-dwelling nature of Archeopteryx.

Ornithologist: The curvature of the claws of modem tree-dwelling birds

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Ornithologist: The curvature of the claws of modem tree-dwelling birds

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