Logical Reasoning

PT149 · S4 · Q15 The ancient reptile Thrinaxodon

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

The ancient reptile Thrinaxodon, an ancestor of mammals, had skull features suggesting that it had sensory whiskers.

Conclusion (therefore)

Thrinaxodon was probably warm-blooded.

Evidence (for)

Its skull suggests it had sensory whiskers.

If it had whiskers, Thrinaxadon had hair on other parts of its body, which would have served as insulation.

Insulation would be of little use to a cold-blooded animal.

Evaluate

Usually, on Main Conclusion and Role, they like to avoid putting the Main Conclusion as the final claim, and here the Conclusion is in the final sentence but not the final claim. The support indicator "for" (FABS = for, after all, because, since) tells us the final claim is support.

The argument sort of takes this voyage: 1. its skull suggests that it had sensory whiskers 2. so it probably had other body hair 3. that other body hair would serve as insulation 4. insulation is of little use to a cold-blooded animal 5. so it was probably warm blooded

Goal

We're being asked about something that is part of the Support.

The answers might force us to consider whether it's an Intermediate Conclusion or just a Premise, but let's cross that bridge if/when we come to it.

We might be able to get our answer just by knowing that this claim being asked about was support for the Main Conclusion that Thrina was probably warm-blooded.

15.

Which one of the following most accurately describes the role played in the argument by the statement that if Thrinaxodon had whiskers, it clearly also had hair on other parts of its body, which would have served as insulation that regulated body temperature?

  1. It is a premise offered

    Bad Conclusion Match

    This correctly labels our claim a premise, but incorrectly says it's there to support "insulation would be of little use to a cold-blooded animal". That last claim isn't the conclusion. "Thrina was probably warm-blooded" is the main conclusion". We can also convince ourselves that "insulation regulating body temp would be of little use to a cold-blooded animal" is not a conclusion at all, because no support is offered. If we asked, "Why would insulation be of little use to a cold-blooded animal?", the support would sound like, "Because ... cold-blooded animals don't heat themselves internally. They lie on a rock and absorb solar radiation. Insulation is only useful if you have an internal heat source and want to keep heat from escaping."

    14% picked this

  2. Correct

    It is a premise offered

    Why this is right

    Every claim in this paragraph, other than 'Thrina was probably warm-blooded', was a premise offered in support of the main conclusion. Even if we thought the second sentence qualified as some sort of Intermediate Conclusion, an Intermediate Conclusion is still a premise. We can call an Intermediate Conclusion "a supported premise" and call regular ol' premises "unsupported premises".

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

    75% picked this

  3. It is a conclusion for

    Unsupported

    This answer is testing us on whether it's fair to call this 2nd sentence a(n Intermediate) conclusion. It's tempting to think that the 2nd sentence could be an intermediate conclusion because it uses the Opinion Indicator "clearly", which is frequently used to signify conclusions. But if we subject either claim in this 2nd sentence to the Support Test, we'll see that there wasn't any support provided. "If T had whiskers, then it clearly also had hair on other parts of its body" why should we believe that? why can't something that have whiskers but otherwise be hairless? Support for this would sound like, "There isn't any animal we know of that has whiskers without also having other body hair. Whiskers only evolve in species that have body hair." We definitely don't have any claims like that. "The other body hair on T would have served as insulation that regulated body temperature" why should we believe that? why does body hair have to serve as insulation? couldn't it be for camouflage or for giving young members of the species something cuddly to snuggle with? Support for this would sound like, "Camouflage can be achieved more easily by means of scales or skin coloration. Animals evolve body hair in habitats with cold outdoor temperatures, where survival requires insulating body heat." We don't have any claims like that.

    4% picked this

  4. It is a statement of

    Opposite: show is false

    The argument definitely isn't trying to show that this 2nd sentence is false. It's one of the author's supporting ideas.

    1% picked this

  5. It is offered as an

    Opposite: not used to support

    We're looking for an answer that says this was part of the Support, and this answer says it wasn't used to provide support. The conclusion was that Thrina was probably warm-blooded, which is principally supported by combining the ideas that "Thrina had body hair that served as insulation" (our claim) and that "such insultation would be of little use to a cold-blooded animal".

    6% 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