PT5.S3.Q06 - whale's skeleton

Grace...

I had a hard time understanding why (A) is the right answer. After thinking about it for a day on and off, I came up with this reasoning. Please take a look if my logic behind getting the right answer is correct.

I wonder if this this question can be viewed as Resolve Reconcile type; the premise says the land-dwelling whales needed hind limbs capable of supporting its weight, and conclusion says the fragile limbs of whale found in the fossil is the remnant of whale once lived on land. But I tried to solve it as strengthen question.

This question talks about whales from three different periods; ancient whale (lived before fossilized whale skeleton), fossilized whale, and modern whale.

Premise:
1. Whales once must have needed hind limbs capable of supporting the weight on land.
2. Evolved whales now have only bare remnants of pelvis. (The implication is that it had a more substantial pelvis before)
3. Fossilized whale skeleton had only a partial pelvis and very fragile hind limbs not enough to support its weight.
Conclusion: The fragile hind limbs are remnants of limbs that land-dwelling whale once had.

I initially misunderstood the conclusion as the fragile hind limbs found in the fossil is the remains the whale that was living on land. So land-dwelling whale having fragile limbs is contradiction within the premise... but the correct understanding is the fragile hind limbs newly found in fossil is how the ancient whale evolved to be. The key was a correct understanding of the word "remnant."

So, to summarize it... whale evolution is like this chronologically.

Ancient Whale (ones lived before the newly found fossilized skeleton)
- pelvis? Premise doesn't say it yet.
- had strong hind limbs enough to support its weight on land

Fossilized Whale
- had partial pelvis
- had fragile hind limbs not capable of supporting its weight on land

Modern Whale
- has only bare remnants of pelvis

So, we need to strengthen the conclusion that the fossilized whale skeleton that has fragile limbs is the evolved form of whales limbs that lived on land at one point.

(A) is correct. The confirmation that ancient whale had a full pelvis would strengthen that by evolution it became a partial pelvis (as found in fossil) and now only bare remnant of pelvis.
(B) This weakens the conclusion
(C) irrelevant
(D) I initially chose this answer and that was because I misunderstood what the conclusion meant precisely.
(E) irrelevant.

It became a quite long explanation... I wonder if I am overthinking when it is really a simple question. I would appreciate any confirmation or correction on my reasoning. Thanks!!

Sami

I think you are on to something here but I wouldn't call it a complete resolve reconcile question. I think what's happening is that you are seeing an issue with the stimulus -you identified that at present the whales only have remnants of this pelvis, you also identified that this fossilized whale only had a partial pelvis with fragile limbs. We also know that at one point it was necessary for whales to have a full pelvis to support their weight on land.

So if our task is to strengthen, answer choice "A" fit's in perfectly. If older skeleton had a full pelvis, then this fossilized skeleton of partial pelvis must be a remnant of that.

Often times you will come across stimulus where you will see something slightly wrong with it. It could be the stimulus had a flaw or an issue and the correct answer choice a lot of times will fix that issue. So in that case in a strengthening answer choice it seems like its resolving the issue. While if you had to weaken it, you would make that gap worse! Maybe the older skeleton discovered did not have a pelvis!

I hope this helped. Great job at seeing the issue in the stimulus.

Grace...

Thank you, Sami. Your explanation was very concise and easy to understand.