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

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Manager
Joined: 12 Dec 2016
Posts: 96

Kudos [?]: 9 [0], given: 44

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

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25 Sep 2017, 20:14
I was stuck between A and B, then I decided to apply the negation technique.

B. Not all creatures that fly by flapping wings have a network of blood vessels in the skin of their wings. If that is true, it doesn't completely destroy the argument. Sandactylus could still be in that group of creatures which fly by flapping their wings and have the network of blood vessels.

A. Sandactylus would have networks of blood vessels in the skin of their wings even if these networks were of no use to Sandactylus. If this is true, then the author cannot conclude that Sandactylus must have flown by flapping their wings, just because they had blood vessels in the skin of their wings.
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Senior Manager
Joined: 26 Dec 2015
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Re: Networks of blood vessels in bats' wings serve only to disperse heat g [#permalink]

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04 Oct 2017, 11:47
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?

* ASSUMPTION Q. First, ID Conclusion: 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
- THEN, negate A/C to BREAK Conclusion

(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.
- S would still have these network of blood vessels regardless of whether or not they worked...this BREAKS the idea that S flew by flapping its wings.

(B) Not All creatures that fly by flapping their wings have networks of blood vessels in the skin of their wings.
- Not concerned with "all creatures". also, "not all" could mean 1 or 99% of creatures. Unsure where S falls here.

(C) Winged dinosaurs that flapped their wings in flight would not have been able to fly more effectively than winged dinosaurs that could only glide.
- Out of scope - who cares about flying effectively?

(D) If Sandactylus flew by flapping its wings, then paleontologists would certainly not be able to find some evidence that it did so.
- Out of scope. Does not address networks of blood vessels or the dispersion of heat generated by flight.

(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.
- Out of scope. Do not care about other ways to disperse heat...what do blood vessels do?

Kudos [?]: 58 [0], given: 1

Re: Networks of blood vessels in bats' wings serve only to disperse heat g   [#permalink] 04 Oct 2017, 11:47

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

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