Even the earliest known species

Answer choices

1. A

   Correct61% picked this

   Known fossils of early land animals include fossils of animals that lived relatively soon after the first

   Why this is right

   This answer is playing off a distinction LSAT has tested numerous times: earliest known fossils ? earliest fossils If we negate this answer, it's saying, "The fossils we have of early land animals do not include any fossils of animals that lived relatively soon after the first emergence of land animals". That weakens a ton! The author's evidence is, "look at these fossils! these animals had highly evolved adaptations. They must have evolved them very rapidly." But if we respond with this negation, we're saying, "Those fossils don't belong to the early crop of land animals. You've only got fossils of animals that lived long after the first emergence of land animals. So there's no reason we need to think they evolved these adaptations very rapidly. Now, if you could show me a fossil of an animal that lived relatively soon after the first emergence of land animals and it had these highly evolved adaptations, then, sure, I'd agree they evolved very rapidly."

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

   61%
2. B

   Too Strong: only a small number2% picked this

   Fossils from the late Silurian period represent only a small number of the animal species that were

   There's no reason the author needs to assume anything about what proportion of all animals these fossils represented. Whether they represent only a small number vs. a pretty moderate number would make no difference to this argument.

   2%
3. C

   Out of Scope1% picked this

   No plants were established on land before the late

   Out of Scope: plants Too Strong: no This argument has nothing to do with plants. The author definitely hasn't committed herself to the extreme position that "there were zero plants established on land prior to 400 million years ago". (I'm pretty sure trees pre-date all animal life)

   1%
4. D

   Out of Scope14% picked this

   No present-day species of aquatic animal is descended from a species of animal that once

   Out of Scope: present-day Too Strong: no Nothing in this argument has anything to do with present-day species, so the author doesn't need to assume a single thing about them, especially not an extreme claim like "not a single present day aquatic species descended from an animal that once lived on land."

   14%
5. E

   Too Strong: all22% picked this

   All animals alive in the late Silurian period lived either exclusively on land or exclusively

   The author hasn't committed to an incredibly unlikely and extreme position that "every single animal alive 400 million years ago lived exclusively on land or exclusively in water". In fact, by mentioning amphibious animals, the author seemed to even imply a contradiction to this.

   22%