Ornithologist: The curvature of the claws

Answer choices

1. A

   Too Strong8% picked this

   Modern tree-dwelling birds are the direct descendants

   If modern tree-dwelling birds were indirect descendants of Archeo, is that going to be a big objection? No. The author is only establishing that Archeo is birdlike to add plausibility to the idea that Archeo used its curved claws to perch in trees like modern birds. She isn't trying to claim that modern birds descended directly from Archeo.

   8%
2. B

   Correct68% picked this

   Archeopteryx made use of the curvature of

   Why this is right

   Haha, what a jerky correct answer. This falls into the category of "something that would have to be true for the author's story to be plausible". If we negate this, and Archeo "made no use of the curvature of its claws", then it would pretty much destroy the argument, since you can't really perch on a tree branch unless you curve your claws around the branch. The author was assuming a similarity between Archeo and modern birds -- we know they both have curved claws, and since modern birds use those curved claws to perch in trees, the author was assuming that Archeo similarly used its curved claws to perch in trees (which is how she arrived at the conclusion that it was probably a tree-dwelling creature). If Archeo never even used the curvature of its claws, then that assumption breaks down.

   Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.

   68%
3. C

   Too Strong16% picked this

   There have never been tree-dwelling birds without

   The author's argument isn't going to be ruined if we negate this and say, "there was at least one species of bird that dwelled in trees but didn't have curved claws". The author is coming closer to assuming that "there has never been a bird that didn't dwell in trees that did have curved claws", but that would still be phrased too strongly.

   16%
4. D

   Irrelevant1% picked this

   Archeopteryx was in fact the earliest

   It doesn't make any difference to the author's argument whether Archeo turns out to actually be the earliest birdlike creature. Whether it's the earliest or the 2nd earliest wouldn't change the argument in the slightest.

   1%
5. E

   Too Strong8% picked this

   The curvature of the claws is the only available evidence for the claim that

   Too Strong: only Only Thing Mentioned ≠ Only Thing In addition to curved claws, Archeo is identified as a birdlike creature (and many/most birds dwell in trees), so it's almost contradicted to say that curved claws are the only available evidence. But even if the paragraph hadn't said "birdlike creature" -- just because curvature of claws is the only evidence the author mentioned doesn't mean she's assuming it's the only evidence that exists. If we negate this, and say that "there is additional evidence for the claim that Archeo was tree-dwelling", that would help the author's argument, not hurt it.

   8%