Logical Reasoning

PT5 · S3 · Q6 As air-breathing mammals, whales

A free, expert breakdown of this official LSAT Logical Reasoning question.

  • Save & drill this skill — build targeted practice sets from questions like this one

  • Video walkthroughs — watch every question solved step by step

  • 81 official LSATs — as questions, timed sections & full-length tests

Start practicing free

As air-breathing mammals, whales must once have lived on land and needed hind limbs capable of supporting the mammals’ weight.

Conclusion (in question stem)

The fragile hind limbs are remnants of limbs that land-dwelling whales once had.

Evidence

Whales are air-breathing mammals, which suggests they must have once lived on land and needed hind limbs that could support their weight.

Whales have the bare remnants of a pelvis.

The fossilized whale skeleton has fragile hind limbs that couldn't support the animal's weight on land and had a partial pelvis.

Evaluate

The background is essentially telling us that whales, the modern day version that live in oceans, evolved from a whale ancestor that walked on land with a full pelvis and limbs that could support their blubbery weight.

Currently, whales have no limbs (common sense) and barely have a pelvis.

It sounds like what we're looking at here would be some evolutionary middle ground between those two stages. As the whale transitioned from being land dwelling to being ocean dwelling, we'd see it go from full pelvis to partial pelvis to bare remnants of a pelvis. And we'd see it go from sturdy limbs to weak limbs to no limbs.

Goal

We are looking for evidence that makes it more plausible that these fragile hind limbs are indeed remnants from a time when whales were land-dwelling mammals.

6.

If the statements above are true, which one of the following, if also true, would most strongly support the conclusion that the fragile hind limbs are remnants of limbs that land-dwelling whales once had?

  1. Correct

    Whale bones older than the

    Why this is right

    By stating that whale bones older than the fossilized hind limbs confirm ancient whales had full pelvises, this strongly suggests that at one point in time, whales had fully functional pelvises with weight-supporting limbs. That makes it more plausible that these fragile hind limbs came AFTER the stage when whales walked on land and BEFORE whales became fully aquatic creatures.

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

    75% picked this

  2. No skeletons of ancient whales

    Opposite (if anything)

    This seems to hurt the story that whales once lived on land. We have no evidence of limbs that would made them capable of walking on land.

    6% picked this

  3. Scientists are uncertain whether the

    No Impact

    Mentioning uncertainty about nonfunctioning limbs in other mammals doesn't contribute evidence about whale ancestors specifically. This creates ambiguity regarding evolution patterns but does not clarify the connection for whales.

    3% picked this

  4. Other large-bodied mammals like seals

    Weakens (if anything)

    This would potentially help someone argue that the fragile hind limbs aren't a sign of life on land, but maybe just a habit of temporarily resting on rocks or beaches.

    16% picked this

  5. Some smaller sea-dwelling mammals, such

    No Impact

    The fact that modern dolphins don't have visible hind limbs (neither do whales) doesn't tell us anything about what to make of these fragile hind limbs that whales apparently once had.

    1% picked this

Continue the review in LSAT Lab

Save this question, watch the video walkthrough, and drill similar questions in your LSAT Lab account.

Save and practice this skill
LSAT Lab

Turn this review into a targeted study plan.

Save this question, drill more like it, watch the video walkthrough, and track your progress in your LSAT Lab account.

Start practicing free