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# Networks of blood vessels in bats' wings serve only to disperse heat g

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Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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Updated on: 24 Apr 2018, 08:12
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The Official Guide for GMAT Review, 11th Edition, 2005

Practice Question
Question No.: CR 89
Page: 493

Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

The argument in the passage relies on which of the following assumptions?

(A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.

(B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.

(C) Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide.

(D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so.

(E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

Originally posted by kdhong on 05 Dec 2005, 21:19.
Last edited by GMATNinjaTwo on 24 Apr 2018, 08:12, edited 8 times in total.
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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16 Dec 2005, 05:09
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i will try to explain.

let network of blood cells = x
heat dispersion = y
Sandactylus = z

its given that x can "only" do y. but its not given that y cannot be done any other way in a creature. its also given that z has x. and the conclusion is that in z, x does y.

it assumes that in z, y cannot be done any other way than x. and thus assumes that in z , x exists with a purpose and it is given that x has only one purpose that is y

hence A

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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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25 Sep 2006, 20:37
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1
A says that Sandactylus used its network of blood vessels. Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Based on this, I would say answer is A.
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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25 Sep 2006, 22:55
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I am up for (A) too.
(E) says heat generated in flapping its wings(we havent yet established if sandalyctuses flapped their wings).
(B) is of the type
if A then B
therefore,if B then A(which is wrong)
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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13 Dec 2008, 05:38
1
diegmat wrote:
Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

The argument in the passage relies on which of the following assumptions?

A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.

B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.

C) Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide.

D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so.

E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

Great question. I now realise that it should indeed be A.

E is wrong:
E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings. IMO, there is nothing to suggest that heat is dispersed only by blood vessels. It says that blood vessels are there only to disperse heat, but this does not suggest the reserve is true.
Anyone disagrees?
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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08 Mar 2013, 23:00
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diegmat wrote:
Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

The argument in the passage relies on which of the following assumptions?

A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.

B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.

C) Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide.

D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so.

E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

Responding to a pm:

This is not an easy question - especially if you are trying to explain the answer.
So first let's try to understand how the argument is structured. I will use variables to make it easier:

Networks of blood vessels in wings - A
heat generated in flight by flapping wings - B

Given Argument:
Bats have A. Bats have B. A's only job is to get rid of B.

What is the assumption? That A must have had a purpose in Dinos too (getting rid of B). You cannot have A without having a job for it. Just because Dinos had A, we are concluding that they must have had B too. We are assuming that A must have had a purpose. This is option (A) and is the answer.

Are we assuming that we cannot get rid of B without A? No. (This is what option (E) says)
When would this be the assumption?
If the argument were a little different: Dinos had B. Hence, Dinos had A too.
In this argument, the assumption would have been that we cannot get rid of B without A.
But given the original argument, this is not the assumption. Hence, answer is not (E).
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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09 Mar 2013, 04:05
2
To mun
i can explain this to u like this though its difficult to parse in words
try and negate B : not All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.
that means out of 100 creatures ,lets say, 95 falls into this category and 5 do not .so with this information u cannot be sure as into which category does this particular species fall( it might be in 95 category in that case the conclusion holds or it might be into 5 category and in that case the conclusion will fall apart ) and hence negating B is not making the destroying the conclusion
does it make sense ?
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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08 Apr 2014, 23:29
Between A & E

E- Supports that the Srus used to flap its wings any ways but had no mechanism to diesperse the heat but the blood vessels
A- Supports the conclusion that the Dino has blood vessels-->Hence it flapped its wings..As blood vessels did not serve any other purpose & neither were they redundant
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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23 Jun 2014, 21:18
1
Here is my analysis:

Premise 1: Blood vessels in the bats' wings help to dissipate the heat
Premise 2: Blood vessels were present in the Sandactylus.

Conclusion : Blood vessels in the wings prove that Sandactylus flew by Flapping

By saying this, the author is assuming too much
1. Blood vessels in the wings are not used for any other purpose or are present not without a purpose . For eg: They might be used for blood circulation, possibly.
2. Sandactylus is much like Bat in terms of physiology
etc etc.

Let's look at the 2 most popular choices A) and B)

a) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.

Negated -> Sandactylus could have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.
This option is aligned with our assumption 1, and therefore the negated statement destroys the argument. For the argument to work we have to believe that the blood vessels are present for a purpose of dissipating heat.

b) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.
Negated -> Not all creatures that fly/flew by flapping their wings have networks of blood vessels in the skin of their wings.

This doesn't destroy the argument, since the author is not forcing us to believe in general that blood vessels are needed to dissipate heat generated by flapping. There could be other animals for example: a pigeon, that might fly by flapping might not have blood vessels. This is not opposed by author. Just that the anatomy of the bats and Sandactylus is similar, in that their blood vessels are used for this specific purpose.

Therefore, A) is clear answer here.
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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25 Jun 2014, 06:06
1
Someone please update the OA for this question. OA is indeed A but the spoiler shows C.

Anyways, here is my approach for this question -

The question asks us to find the assumption made in the argument. Observe the gap between the premises and the conclusion.

Premises:
Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings.

Conclusion:
Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

Gap:
Having similar networks of blood vessels in Sandactyls to those found in bats proves that Sandactylus also flew by flapping its wings. In the other words this network of blood vessels in Sandactylus serves no purpose other than to disperse the heat generated by flapping wings.

Choice A clearly identifies the gap and hence is the best choice.
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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05 Jul 2014, 04:58
6
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The argument in the passage relies on which of the following assumptions?

(A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactytus.
the network of blood vessels serve only to disperse heat generated in flight.
so it has a certain function and usage.
negation of this option will break the argument apart

(B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings. we can infer from the argument that those creatures that their wings have networks of blood vessels in the skin of their wings fly by flapping their wings not vice versa.

(C) winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide.

(D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so. they've already found some evidence.. network of blood vessels.

(E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

we have a premise:Networks of blood vessels in bats’ wings serve only to disperse heat generated in flight. ---> there might be other ways that bats disperse heat generated in flight. however, the usage of Networks of blood vessels in bats' wings is only to disperse heat generated in flight------- so, E is incorrect
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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26 Oct 2014, 10:44
I may be tempted to reject A on the grounds that it's just a conditional statement leading to a statement that confirms the event never occurred. A bit of SC logic : If < simple past> , past perfect construction is used for an event that never occurred.

The conclusion is that the finding ' provides evidence for the hypothesis...'. Does A provides evidence of the hypothesis? Probably not.
Does E provide evidence for the hypothesis? Sure, it does.

May be a bit of over-thinking but it would be good to know the source of this question ( not from OG for sure).
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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26 Oct 2014, 19:35
kishgau wrote:
I may be tempted to reject A on the grounds that it's just a conditional statement leading to a statement that confirms the event never occurred. A bit of SC logic : If < simple past> , past perfect construction is used for an event that never occurred.

The conclusion is that the finding ' provides evidence for the hypothesis...'. Does A provides evidence of the hypothesis? Probably not.
Does E provide evidence for the hypothesis? Sure, it does.

May be a bit of over-thinking but it would be good to know the source of this question ( not from OG for sure).

This is question number 89 from OG 11. The question and solution are official and perfect. Expect to see such questions on the actual exam.

And the option (A) does give you a hypothetical event but that hypothetical event is - if these networks were of no use, they would not have had the network. It is just another way of saying that the networks were useful. 'Networks were of no use' is hypothetical.
In verbal, rules will not help you. Things change depending on context.

The argument assumes that the network of blood vessels was not present just like that - it had a purpose. It was present means it was needed to disperse heat and hence the dinos flapped their wings.
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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28 Oct 2014, 07:52
(A) is definitely right here. The premise of the argument is that the only purpose of blood vessels in bat wings is to disperse heat from flapping. The conclusion is that the flying dinosaur most likely flapped, since it has similar blood vessels. Therefore, the assumption is that the blood vessels served a purpose, any purpose, at all. If they served no purpose (the negation of choice (A)), then the argument about flapping has no basis.

For choice (B), the distractor, it's important to remember that the negation of "All" is "Not all." Even if not all flappers have these blood vessel networks, that tells us little or nothing about animals that do, including both bats and Sandactylus.

Hope this helps!
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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26 Nov 2014, 21:19
2
A indeed is the correct answer. I was stuck between A and E for long. Great question!!! Hope this explanation helps!

Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

F1: Blood vessels in bat ONLY dispersed heat generated in flight
F2: In bats, heat generation was ONLY because bats flapped wings
F3: S glides
F4: There is a view that S could fly flapping its wings too. This view is not proved yet.
C: Since S has a network of blood vessels similar to that of Bats, S flew flapping its wings

GAP: Since in Bats the vessels only served for dispersing heat, in S too they must serve the same purpose

The argument in the passage relies on which of the following assumptions?

A. Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus. Addresses gap

B. All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings. Over generalisation. Questionable too. If all creatures must have this feature then why compare only with the Bat today when scientists have been compared this earlier since they were having a view that S flew?

C. Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide. effectiveness not at all a part of the discussion. OUT

D. If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so. So this evidence is not good enough? Irrelevant

E. Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings. who said they flapped their wings? None knows that yet. Scope shift. Out
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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01 Feb 2015, 05:45
VeritasPrepKarishma wrote:
diegmat wrote:
Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

The argument in the passage relies on which of the following assumptions?

A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.

B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.

C) Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide.

D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so.

E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

Responding to a pm:

This is not an easy question - especially if you are trying to explain the answer.
So first let's try to understand how the argument is structured. I will use variables to make it easier:

Networks of blood vessels in wings - A
heat generated in flight by flapping wings - B

Given Argument:
Bats have A. Bats have B. A's only job is to get rid of B.

What is the assumption? That A must have had a purpose in Dinos too (getting rid of B). You cannot have A without having a job for it. Just because Dinos had A, we are concluding that they must have had B too. We are assuming that A must have had a purpose. This is option (A) and is the answer.

Are we assuming that we cannot get rid of B without A? No. (This is what option (E) says)
When would this be the assumption?
If the argument were a little different: Dinos had B. Hence, Dinos had A too.
In this argument, the assumption would have been that we cannot get rid of B without A.
But given the original argument, this is not the assumption. Hence, answer is not (E).

What is the assumption? That A must have had a purpose in Dinos too (getting rid of B). You cannot have A without having a job for it. Just because Dinos had A, we are concluding that they must have had B too.

What if A must have had a purpose in Dinos too other than B?

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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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01 Feb 2015, 22:51
Mahmud6 wrote:
VeritasPrepKarishma wrote:
diegmat wrote:
Networks of blood vessels in bats' wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists' recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

The argument in the passage relies on which of the following assumptions?

A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactylus.

B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.

C) Winged dinosaurs that flapped their wings in flight would have been able to fly more effectively than winged dinosaurs that could only glide.

D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to find some evidence that it did so.

E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.

Responding to a pm:

This is not an easy question - especially if you are trying to explain the answer.
So first let's try to understand how the argument is structured. I will use variables to make it easier:

Networks of blood vessels in wings - A
heat generated in flight by flapping wings - B

Given Argument:
Bats have A. Bats have B. A's only job is to get rid of B.

What is the assumption? That A must have had a purpose in Dinos too (getting rid of B). You cannot have A without having a job for it. Just because Dinos had A, we are concluding that they must have had B too. We are assuming that A must have had a purpose. This is option (A) and is the answer.

Are we assuming that we cannot get rid of B without A? No. (This is what option (E) says)
When would this be the assumption?
If the argument were a little different: Dinos had B. Hence, Dinos had A too.
In this argument, the assumption would have been that we cannot get rid of B without A.
But given the original argument, this is not the assumption. Hence, answer is not (E).

What is the assumption? That A must have had a purpose in Dinos too (getting rid of B). You cannot have A without having a job for it. Just because Dinos had A, we are concluding that they must have had B too.

What if A must have had a purpose in Dinos too other than B?

Option (A) states that "A must have had a purpose" - that is the assumption. Without this assumption, the conclusion makes no sense. If A could exist without a purpose, then we cannot say that Dinos had B too. Another assumption would be that A's purpose can only be to get rid of B.
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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06 Feb 2015, 23:14
karishma

Could you please explain why negation did not worked out for B here?

Many thanks
Vikas

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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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09 Feb 2015, 00:10
vikasbansal227 wrote:
karishma

Could you please explain why negation did not worked out for B here?

Many thanks
Vikas

Posted from my mobile device

Networks of blood vessels in wings - A
heat generated in flight by flapping wings - B

Given Argument:
Bats have A. Bats have B. A's only job is to get rid of B.

The assumption is that if someone has A, he has B too.

Option (B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.

It says, all creatures that have B, have A too. This is not our assumption.

If we negate it, we get that there are some who have B but not A. It doesn't kill our conclusion. In our conclusion, we are concerned about people who have A, whether they have B or not. We are not concerned about people who have B, whether they have A or not.
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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04 Jun 2017, 19:44
chshashankreddy wrote:
Networks of blood vessels in bats’ wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. Thus paleontologists’ recent discovery that the winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding.

The argument in the passage relies on which of the following assumptions?

(A) Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactytus.

(B) All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.

(C) winged dinosaurs that flapped their wingsin flight would have been able to fly more effectively than winged dinosaurs that could only glide.

(D) If Sandactylus flew by flapping its wings, then paleontologists would certainly be able to findsome evidence that it did so.

(E) Heat generated by Sandactylus in flapping its wings in flight could not have been dispersed by anything other than the blood vessels in its wings.
:
Fact:Networks of blood vessels in bats’ wings serve only to disperse heat generated in flight. This heat is generated only because bats flap their wings. winged dinosaur Sandactylus had similar networks of blood vessels in the skin of its wings.

Missing Information:Sandactylus would not have had networks of blood vessels in the skin of its wings if these networks were of no use to Sandactytus. i.e., the network of blood vessels had a purpose

Conclusion: This provides evidence for the hypothesis that Sandactylus flew by flapping its wings, not just by gliding

The right choice needs to fill a gap. Choice A does that and hence is the missing information.

So we see that the missing information starts from the fact shown in bold and leads to the conclusion.
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