The Smithsonian Museum of Natural History recently unveiled a new

Question

The Smithsonian Museum of Natural History recently unveiled a new exhibit featuring all 225 bones of the fossilized skeletons of two Apatosauruses. Despite the fact that both skeletons are from the same species, one has a tail almost one meter longer than the other.

Which of the following, if true, is the least reasonable explanation for the differences in tail length of the Apatosaurus skeletons described in the passage above?

(A) The skeleton with the longer tail is from an animal that lived 2 million years before the one with the shorter tail.

(B) Scientists believe that Apatosauruses would sometimes shed part of their tail in an attempt to escape a predator.

(C) One skeleton is of an immature Apatosaurus while the other is from an adult male.

(D) One skeleton belonged to a male while the other belonged to a female.

(E) Scientists believe that Apatosauruses generally grew in size according to the food supply available in their environment.

Fatineel · Accepted Answer

This is one of those questions where there are some twisted logic and assumptions.

I originally hesitated between A and B until i read the passage again and found " all 225 bones" which means that essentially the fossilized Apatosauruses did retain their full skeletons so it's kind of unreasonable to think that one of them had it's tail "cut" but then i should assume that tails have bones.
(this is a pretty meager attempt to explain my reasoning

)

To be honest, I would really love to know if the gmat test has these types of questions, I personally find the OG CR questions and answers way more "straightforward" logic than those of prep companies.

) To be honest, I would really love to know if the gmat test has these types of questions, I personally find the OG CR questions and answers way more "straightforward" logic than those of prep companies.

Palak74 · Answer

I think the answer is B because it focuses on the Tail only. 
In other options if the two are male/female or adult/immature then the tail should not be the only bone which should have a difference. Other bones of the body should also show the difference.

For option A : if it said that the difference in evolution periods makes a difference in the bone size then it would make some connection to the statement. This option as is would become an assumption that we are adding.

Hence B seems to be the most logical answer

Ozzy11100 · Answer

Ehh... another question of questionable (imo) quality from a 3rd party provider.

I understand the question writers logic, but it's a hell of an assumption  to assume that an animal CAN'T shed a bone fragment when escaping from a predator.   Which is the premise upon which the OA rests.

Like,  who among us can say with certainty that that's a valid assumption? Why couldn't they shed a bone fragment? The bones of the tail could be in sufficient excess of 1 meter long. Who's to say that they aren't? I doubt there are many zoologists/palaeontologists here.

Basically, the OA requires us to make certain fairly unrigorous assumptions to rule out the other answers,  yet requires us NOT to make similar assumptions about the correct answer.  It's a bit like having your cake and eating it too!

A decent try, but another swing and a miss, nevertheless, in my opinion.

ShreyasJavahar · Answer

I did initially use the reasoning that an animal doesn't "shed" something that is on the inside. By definition, shedding is the sloughing off of an external layer or component.
Another run-through of the passage revealed a stronger reason for B to be the answer. The phrase "all 225 bones" implies straight away that there are no bones missing from either fossil, so regardless of any presupposed zoological acumen, option B has the least bearing on why one fossil's tail is shorter. The fact that no bones are absent from either fossil tells us that neither animal lost part of its tail by the evasive manoeuvre outlined in B.

I'd like to hear your points of agreement/disagreement so we can get to the bottom of this question.

Ozzy11100 · Answer

Hey mate,

The crux of my criticism rests on this assumption, as you've made, that, "The fact that no bones are absent from either fossil tells us that neither animal lost part of its tail by the evasive manoeuvre outlined in B." I'm saying it's not unreasonable to believe that an animal could lose part of it's tail WITHOUT losing bones, i.e. it loses part of a bone - total number unchanged.

In light of this, I think the arguments for/against the OA's correctness are largely semantic, and that one could make similar arguments to justify the correctness of the remaining answer choices.

ShreyasJavahar · Answer

Ah alright, I see what you mean. It is a bit of a reach though, one shouldn't have to look at answer choices with such a nuanced perspective. But then again, option A warrants quite a reach as well, and that wouldn't have been the case with an official question. I see your point. Cheers.

Helpmecat · Answer

I think the answer is E. The passage only mentions a difference in tail length.
Option E says the whole body size changes based on food supply, which would affect the whole skeleton, not just the tail. Therefore, it does not specifically explain why only the tail length differs. Idk why the answer is B.

AbhishekP220108 · Answer

Helpmecat

Let me try to help, PS there are two many underlying assumptions, we are assuming tail has bone which is not explicitly mentioned. Second the meaning of shedding but since the passage mentioned all 225 bones, we are taking into consideration a few things

Passage states two facts
1. All 225 bones are there in skeleton
2. Tail length difference. This doesnt mean the part of tail is cut, its the natural length. Think of a lizard, the tail of one is naturally shorter than the other one. Its not that the tail part is lost.

Option B states they shed the part of there tail to escape from predator. If they are sheding then they are loosing the bone, if the bone is lost then how all the 225 bones are there.

Option E says based on food supply there is change in body structure size. This can be the case if the food supply is less for one species its length cannot grow that much and tail is part of the body. So E is somewhat resolving the paradox. But B is contradicting the two facts

Hope this helps

Adit_ · Answer

Way too many assumptions involved here.
 Bunuel  could this be a valid GMAT question?

guddo · Answer

The Smithsonian Museum of Natural History recently unveiled a new exhibit featuring all 225 bones of the fossilized skeletons of two Apatosauruses. Despite the fact that both skeletons are from the same species, one has a tail almost one meter longer than the other.
 
 Which of the following, if true, is the least reasonable explanation for the differences in tail length of the Apatosaurus skeletons described in the passage above?

We need the choice that, even if accepted as true, is the  least reasonable  way to explain why two individuals of the same species could have different tail 
lengths.

(A) The skeleton with the longer tail is from an animal that lived 2 million years before the one with the shorter tail.

A long time gap can plausibly line up with population level change within a species, so this can reasonably explain a size difference.

(B) Scientists believe that Apatosauruses would sometimes shed part of their tail in an attempt to escape a predator.

This is the least reasonable because it relies on a very special, unusual mechanism (deliberately shedding a major body part) rather than ordinary biological variation like age, sex, or growth conditions.  So even if someone claims this happened, it is the weakest, least “normal” explanation among the choices.

(C) One skeleton is of an immature Apatosaurus while the other is from an adult male.

Age differences naturally lead to size differences, including tail length, so this is a reasonable explanation.

(D) One skeleton belonged to a male while the other belonged to a female.

Sex based size differences within a species are common enough, so this is a reasonable explanation.

(E) Scientists believe that Apatosauruses generally grew in size according to the food supply available in their environment.

Different food supply can plausibly affect overall growth, and tail length can vary as part of that, so this is reasonable.

Answer: (B)

AbhishekP220108 · Answer

Adit_  I doubt that its a valid question, but its good to practice. So dont bother much

Adit_ · Answer

For some questions like this it does seem like you need to align your thought in a certain way to get to the answer. IMO I would not say B is the "least" explanatory of the situation here because we are making a "scientific" assumption that 1) tails have bones 2) tails cant shed technically and all this is rather too scientific and IMO doesn't relate to GMAT in a full manner.

AbhishekP220108

Adit_ I doubt that its a valid question, but its good to practice. So dont bother much

The Smithsonian Museum of Natural History recently unveiled a new

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Critical Reasoning (CR) Questions

The Smithsonian Museum of Natural History recently unveiled a new

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards