Paleontologists have discovered fossils of centipedes that are

Question

Paleontologists have discovered fossils of centipedes that are 414 million years old. These fossils are at least 20 million years older than the earliest land-dwelling animals previously identified. The paleontologists are confident that these centipedes lived on land, even though the fossilized centipedes were discovered in rock that also contained fossilized remains of animals known to be water-dwelling.

The paleontologists' view would be LEAST supported by the truth of which one of the following?

(A) The legs of the fossilized centipedes were particularly suited to being a means of locomotion on land.

(B) All of the centipedes that had previously been discovered were land dwellers.

(C) The rock in which the fossilized centipedes were found was formed from mud flats that were occasionally covered by river water.

(D) Fossils of the earliest land-dwelling animals that had previously been identified were found in rock that did not contain fossilized remains of water-dwelling animals.

(E) Fossils of spiders with respiratory systems adapted only to breathing air were found in the same rock as the centipede fossils.

Source: LSAT

nightblade354 · Accepted Answer

Paleontologists have discovered fossils of centipedes that are 414 million years old. These fossils are at least 20 million years older than the earliest land-dwelling animals previously identified. The paleontologists are confident that these centipedes lived on land, even though the fossilized centipedes were discovered in rock that also contained fossilized remains of animals known to be water-dwelling.

The paleontologists' view would be LEAST supported by the truth of which one of the following?

(A) The legs of the fossilized centipedes were particularly suited to being a means of locomotion on land. --  This says they were built to be on land, which supports our conclusion

(B) All of the centipedes that had previously been discovered were land dwellers. --  This, again, supports out conclusion based on history
 
(C) The rock in which the fossilized centipedes were found was formed from mud flats that were occasionally covered by river water. --  This says that fish fossils could have been placed with our creature well after our creature had already been fossilized. Therefore, this supports our conclusion

(D) Fossils of the earliest land-dwelling animals that had previously been identified were found in rock that did not contain fossilized remains of water-dwelling animals. --  So no other water-dwelling animals were found with other land-dwelling animals. This doesn't 100% weaken our conclusion, but it certainly doesn't support it. This is our answer

(E) Fossils of spiders with respiratory systems adapted only to breathing air were found in the same rock as the centipede fossils. --  This says that air-breathing species were found with our creature. This would support the idea, albeit not well, that our creature was land-dwelling, too. Thus, this supports or conclusion

sobby · Answer

I will go with D here :

(C) The rock in which the fossilized centipedes were found was formed from mud flats that were occasionally covered by river water--this actually support the Paleontologists .It says that the rock that has been found was formed from mud flats that were  occasionally  (not most) covered by river water, so there may be chances , some of the water animals got fossilized...

(D) Fossils of the earliest land-dwelling animals that had previously been identified were found in rock that did not contain fossilized remains of water-dwelling animals. ---So what , it did not resolve the contention that why this time we have water animal fossilized in rock or Is centipedes are water dwelling ???

Mizar18 · Answer

The paleontologists' view would be  LEAST supported  by the truth of which one of the following?

Conclusion: Despite the fact that fossilized centipedes were discovered in rock that also contained remains of animals known to be water-dwelling, paleontologists are sure that centipedes lived on land.

We must find a choice that  least support our argumen t, so the right answer choice could be a weak strengthener  ,  an irrelevant option  or  a weakener.

(A) The legs of the fossilized centipedes were particularly suited to being a means of locomotion on land.

This one strengthen the theory that centipedes lived on land -  Incorrect

(B) All of the centipedes that had previously been discovered were land dwellers.

This one is an irrelevant option. The fact that previously discovered centipedes were land dwellers does not prove anything about the new discovered fossils. -  Incorrect

(C) The rock in which the fossilized centipedes were found was formed from mud flats that were occasionally covered by river water.

You can make several assumptions about this one, but the most relevant word in this sentence is  "ocassionally",  so you can say that this option actually strengthens the argument by saying that MOST of the time the land sorrounded by the mud flats was not covered by water. -  Incorrect

(D) Fossils of the earliest land-dwelling animals that had previously been identified were found in rock that did not contain fossilized remains of water-dwelling animals.

Now we have something. Previous discoveries of the  earliest land-dwelling animals  did  not contain fossilized remains of water-dwelling animals , so this options makes us doubt by stating that this discovery has a  new trait  (rock that also contained remains of animals known to be water-dwelling). If we have new information, why are we concluding that these fossilized centipedes were also land-dwellers? -  Correct

(E) Fossils of spiders with respiratory systems adapted only to breathing air were found in the same rock as the centipede fossils.

Fossils of animals with respiratory systems found along the centipede fossils strengthen our conclusion.  Incorrect

YashYashkratos · Answer

A) strengthens 
B) strengthens 
C) weak weakener- use of the word occasionally and the fact we know nothing about formation of rocks in general and what this information really proves.

D) Correct- Remains of water dwelling animals are not usual thus supporting an argument that weakens the conclusion.

E) strengthens

Gilmore · Answer

Hello,

I am struggling to wrap my head around Option D because one could argue that the logic used to eliminate Option C, namely, " The fact that previously discovered centipedes were land dwellers does not prove anything about the newly discovered fossils ", can also be applied to Option D.

The fact that the earliest land-dwelling animals previously identified were found in rock that did not contain fossilised remains of water-dwelling animals does not, in itself, prove anything about the newly discovered fossils.

I chose Option C because I thought that the statement that the area was occasionally covered with water hinted that these centipedes might have been amphibious. Again, that probably involves too many assumptions on my part, but I had eliminated most of the other answer choices, so I ended up selecting this one

guddo · Answer

I think the key is that this is a  LEAST support  question, so an answer does not have to prove anything. It only has to make the paleontologists’ view more or less plausible.

(C) actually provides useful support. If the rock formed from mud flats that were only  occasionally covered by river water , then land-dwelling animals and aquatic animals could naturally end up preserved in the same rock. So the presence of water-dwelling fossils no longer gives us much reason to think the centipedes were aquatic. “Occasionally covered” does not suggest the centipedes were amphibious.

(D), by contrast, gives us no useful information about these centipedes. It merely says that some previously known land animals were found without aquatic fossils nearby. That tells us nothing about whether land animals can also be preserved alongside aquatic ones.

Also, the reasoning you mention actually applies more closely to (B), but even there, knowing that  all previously discovered centipedes were land dwellers  gives at least some probabilistic support that these centipedes were too. (D) provides even less.

So (D) is the best answer.

Paleontologists have discovered fossils of centipedes that are

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Paleontologists have discovered fossils of centipedes that are

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