LR Question 24 Explanation
QUESTION TEXT: Most land-dwelling vertebrates have rotating limbs terminating…
QUESTION TYPE: Most Strongly Supported
CONCLUSION: We land dwellers have rotating limbs ending in digits (e.g. arms with fingers, legs with toes.)
New evidence shows that an aquatic ancestor of land mammals might have been the first to evolve this trait.
ANALYSIS: We don’t have very much information in this stimulus. The wrong answers all talk about things of which we know nothing.
___________
- Who knows? Maybe the Acanthostega was very successful. Its skeleton was only too feeble for land movement, but the animal may have done just fine in water.
- There’s no evidence for this extreme statement. For example, most fish have spines but so do land animals. Does that mean a spine is a disadvantage for land animals?
- No. The fact that the Acanthostega couldn’t move on land is evidence against this idea.
- We have no clue. We only have information on one aquatic species and we don’t know if the Acanthostega found its limbs to be an advantage or not.
- CORRECT. The anatomical characteristics are the rotating limbs with digits. Some aquatic animals refers to the Acanthostega, which had such limbs.
Those limbs likely present a survival advantage on land because they are useful for land movement and most land animals kept this feature.
More Resources for Most Strongly Supported Questions
- Intro Course lesson: This intro course lesson covers Most Strongly Supported questions.
- Mastery Seminar lesson: This LR Mastery seminar lesson covers most strongly supported questions.
I got caught on the “some” in answer choice E. How does “some” only mean a single unit in this context? Or does “some” also cover any undiscovered aquatic animals with land animal qualities? The stimulus seems to indicate only the Acanthostega had this property.
Good question! In LSAT reasoning, some typically means at least one but possibly more (which can be frustratingly vague, but think about the dictionary definition of some – it’s an unspecified amount). Some means at least one, but not as many as most. So some is within the range of 1-50%, if you had to think about it in numbers.
So, when E states some aquatic animals, it is simply saying at least one aquatic species (Ancathostega) had a trait that was advantageous for land movement. Note that the stimulus doesn’t rule out the possibiliy that other aquatic animals also had this characteristic, even if Acanthostega is the only example given. “Some” can be used in a broad way, meaning the statement remains valid whether Acanthostega is the only case or if there are undiscovered aquatic species with similar traits.
This is why E is supported, it doesn’t overstate the conclusion but makes a safe inference based on the stimulus. Let me know if you have further questions!