Q9 - Ornithologist: The curvature of the claws

[carly.applebaum]

i'm just really confused as to how to approach this question.
i started with:

MTD bird claw curve --> perch

Archeopteryx claw curve --> perch --> TD creature

...but then i didn't know where to go from here

by POE i got the correct answer because the rest seemed irrelevant and in (E) sounded too extreme since the ornithologist's conclusion said "probably" and not "must be"

thanks in advance!

[timmydoeslsat]

It looks like your instincts took over after formal diagramming did not really lend itself to much use. And this issue is common. It is better to see what is going on from an abstract perspective.

In this argument, what is at issue is the idea that a creature actually dwells on trees simply because it has the ability to do so.

We also have the issue that the paleontologist brings up which is that we know a characteristic of tree dwelling birds. However, this does not mean that the tree dwelling birds alone have this characteristic. As the paleontologist showed us, other animals have the same characteristic, yet are not tree dwelling birds.

It is necessary to assume (B). If the Archeopteryx did not make use of its claws, then we would not be able to conclude that it was a tree dwelling creature.

This was the earliest known birdlike creature. It may be true that it had the consistency of those curved claws, but did it put them to use at that time? Perhaps it took thousands of years before birds put them to use.

Answer choices:

A) We are told that Archeopteryx is the earliest known birdlike creature. The argument does not depend on it being a direct heritage to tree dwelling birds.

C) We do not need to know that there have never been tree dwelling birds without curved claws. Some of the dwelling birds can have curved claws and it does not harm our reasoning, which is that if you the curved claws....you probably are a dweller.

D) We do not need to know if it is the earliest. Even if it is not the earliest, the reasoning is not harmed. Its the issue of the curved claws and concluding probability of that creature being a tree dweller on that fact.

E) We do not need this to be the only evidence. You could bring along more evidence to support this assertion of the Archeopteryx probably being a tree dwelling creature and this argument would be fine.

[ManhattanPrepLSAT1]

Nice work Timmy!

One way to think about answer choice (B) is that it protects the argument from the provided evidence quickly becoming irrelevant. If the Archeopteryx did not use the curvature of it's claws and we don't have any further evidence, then it's not probable that the Archeopteryx was tree-dwelling.

[WaltGrace1983]

I would actually say that (C) is a reversal of what we want. The Ornithologist is basically assuming: Claws → Tree-Dwelling. (C) is saying Tree-Dwelling → Claws. However, do notice that in the argument we are talking about one, specific, bird and (C) is talking about the birds in general.

[SJK493]

I was able to identify the correct answer using the process of elimination. While I did manage to answer correctly, I feel that I need clarification on the correct answer, specifically on why it is the necessary assumption.

It has been established that because the Archeopteryx shows curvature of the claws, it probably must have been able to perch on tree limbs. And the gap in the argument is that the ability to perch on tree limbs does not mean that it was tree-dwelling. But the answer says ‘Archeopteryx made use of the curvature of its claws,’ not particularly anything about it being tree-dwelling. Can you provide clarification on this?