• EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep
  • Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep
  • Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep

RC - Two hypothesis - Weaken Question

This topic has 1 expert reply and 21 member replies
Goto page
  • 1,
  • 2
Next
gauravgundal Master | Next Rank: 500 Posts Default Avatar
Joined
06 Apr 2009
Posted:
199 messages
Upvotes:
13

RC - Two hypothesis - Weaken Question

Post Mon Jan 24, 2011 1:35 am
Two opposing scenarios,
the “arboreal” hypothesis and
the “cursorial” hypothesis, have
Line traditionally been put forward con-
(5) cerning the origins of bird flight.
The “arboreal” hypothesis holds
that bird ancestors began to fly
by climbing frees and gliding
down from branches with the
(10) help of incipient feathers: the
height of trees provides a good
starting place for launching flight,
especially through gliding. As
feathers became larger over time,
(15) flapping flight evolved and birds
finally became fully air-borne.
This hypothesis makes intuitive
Sense, but certain aspects are
Troubling. Archaeopteryx (the
(20) earliest known bird) and its
maniraptoran dinosaur cousins
have no obviously arboreal
adaptations, such as feet fully
adapted for perching. Perhaps
(25) some of them could climb trees,
but no convincing analysis has
demonstrated how Archaeopteryx
would have both climbed and
flown with its forelimbs, and there
(30) were no plants taller than a few
meters in the environments where
Archaeopteryx fossils have been
found. Even if the animals could
climb trees, this ability is not
(35) synonymous with gliding ability.
(Many small animals, and even
some goats and kangaroos,
are capable of climbing trees
but are not gliders.)
Besides,
(40) Archaeopteryx shows no obvious
features of gliders, such as
a broad membrane connecting
forelimbs and hind limbs.
The “cursorial”(running)
(45) hypothesis holds that small
dinosaurs ran along the ground
and stretched out their arms for
balance as they leaped into the
air after insect prey or, perhaps,
(50) to avoid predators. Even rudimentary
feathers on forelimbs
could have expanded the arm’s
surface area to enhance lift
slightly. Larger feathers could
(55) have increased lift incrementally,
until sustained flight was gradually
achieved. Of course, a leap
into the air does not provide the
acceleration produced by drop-
(60) ping out of a tree; an animal
would have to run quite fast
to take off. Still, some small
terrestrial animals can achieve
high speeds. The cursorial
(65) hypothesis is strengthened by
the fact that the immediate theropod
dinosaur ancestors of
birds were terrestrial, and they
had the traits needed for high
(70) lift off speeds: they were small,
agile, lightly built, long-legged,
and good runners. And because
they were bipedal, their arms
were free to evolve flapping flight,
(75) which cannot be said for other
reptiles of their time.

-----------------------------------------------------------------
The passage presents which of the following facts as evidence that tends to undermine
the arboreal hypothesis?
A. Feathers tend to become larger over time
B. Flapping flight is thought to have evolved gradually over time
C. Many small animals are capable of climbing trees.
D. Plants in Archaeopteryx’s known habitats were relatively small
E. Leaping into the air does not provide as much acceleration as gliding out of a
tree

IMO: D
With POE, I got down to C and D.
I am not able to justify why answer choice C is wrong.
The line no. 36 does mention about the small animals and their ability to climb trees , this may undermine 'arboreal hypothesis'.

Can anyone help me to answer my silly query of what can be the reason to eliminate answer choice C?

  • +1 Upvote Post
  • Quote
  • Flag
Thanked by: S.M
Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
tgou008 Senior | Next Rank: 100 Posts Default Avatar
Joined
15 Jan 2011
Posted:
43 messages
Upvotes:
9
Post Tue May 17, 2011 1:35 pm
Wow this is a really tough choice between C and D, and I really don't think I can call it either way.
What is the source for this question and what is the OA?

Thanks

  • +1 Upvote Post
  • Quote
  • Flag
ldoolitt Master | Next Rank: 500 Posts Default Avatar
Joined
14 Apr 2007
Posted:
184 messages
Upvotes:
17
Test Date:
None
Target GMAT Score:
780
Post Thu Apr 07, 2011 8:28 am
I believe the answer is D.

Why is C incorrect? Because it doesn't undermine the hypothesis. The passage states

Quote:
The “arboreal” hypothesis holds
that bird ancestors began to fly
by climbing frees and gliding
down from branches
with the
(10) help of incipient feathers: the
height of trees provides a good
starting place for launching flight,
especially through gliding
Your bolded section states

Quote:
(Many small animals...
are capable of climbing trees
but are not gliders
.
Obviously this undermines the hypothesis. However (C) just says "many small animals are capable of climbing trees" which, in and of itself is neutral (or possibly supports) the hypothesis. This answer is, as the CR Bible calls it, a shell game (presenting something from the passage that is slightly tweaked or leaves out some crucial detail)

  • +1 Upvote Post
  • Quote
  • Flag
ronnie1985 Legendary Member
Joined
23 Dec 2011
Posted:
626 messages
Followed by:
10 members
Upvotes:
31
Test Date:
June
Target GMAT Score:
750
Post Sun Apr 01, 2012 7:24 am
Climbing tree is not the license for flying or gliding

_________________
Follow your passion, Success as perceived by others shall follow you

  • +1 Upvote Post
  • Quote
  • Flag
mourinhogmat1 Senior | Next Rank: 100 Posts Default Avatar
Joined
17 Jul 2010
Posted:
53 messages
Upvotes:
1
Post Fri Feb 24, 2012 7:14 pm
Actually D doesn't even weaken the stimulus. I mean just because there are no trees tall enough near the fossil doesn't mean that the bird couldn't climb tall trees elsewhere right?

C does a good job at weakening the argument. The author needs to prove both climbing and gliding to prove the first theory. He only succeeds at the climbing part. Answer choice C forces him to answer gliding part of the argument.

  • +1 Upvote Post
  • Quote
  • Flag
Black Knight Senior | Next Rank: 100 Posts Default Avatar
Joined
02 Feb 2011
Posted:
75 messages
Followed by:
3 members
Upvotes:
6
Post Thu May 19, 2011 12:28 am
I go with C, though D also looks tempting!

  • +1 Upvote Post
  • Quote
  • Flag

GMAT/MBA Expert

Geva@EconomistGMAT GMAT Instructor
Joined
12 Sep 2010
Posted:
905 messages
Followed by:
123 members
Upvotes:
378
GMAT Score:
760
Post Wed May 18, 2011 2:29 am
tgou008 wrote:
Wow this is a really tough choice between C and D, and I really don't think I can call it either way.
What is the source for this question and what is the OA?

Thanks
It's not a tough choice, unless you make it one by second guessing yourself instead of aggressively eliminating. ldoolitt got it right: the fact that small animals can climb does not in and of itself undermine the arboreal hypothesis. For C to be correct, it needs to present the entire undermining fact: that many small animals can climb but cannot fly.

also, D is clearly a piece of evidence used to undermine the hypothesis - the earliest known bird did not have trees high enough to glide from, so it probably developed flight in a different way. Once you have D, there really is no reason to go and talk yourself into choosing a trap answer choice such as C.

_________________
Geva
Senior Instructor
Master GMAT
1-888-780-GMAT
http://www.mastergmat.com

  • +1 Upvote Post
  • Quote
  • Flag
Thanked by: spaniard, S.M
Free 7-Day Test Prep with Economist GMAT Tutor - Receive free access to the top-rated GMAT prep course including a 1-on-1 strategy session, 2 full-length tests, and 5 ask-a-tutor messages. Get started now.
vzzai Senior | Next Rank: 100 Posts Default Avatar
Joined
02 Sep 2008
Posted:
85 messages
Upvotes:
1
Target GMAT Score:
720+
GMAT Score:
650
Post Wed Apr 06, 2011 11:21 pm
IMO D.

Please post the OA.

_________________
Thank you,
Vj

  • +1 Upvote Post
  • Quote
  • Flag
Rezinka Master | Next Rank: 500 Posts Default Avatar
Joined
15 Oct 2010
Posted:
131 messages
Upvotes:
11
Target GMAT Score:
750
Post Thu Mar 03, 2011 9:49 pm
IMO : C
OA please

  • +1 Upvote Post
  • Quote
  • Flag
chendawg Master | Next Rank: 500 Posts
Joined
24 Nov 2009
Posted:
163 messages
Followed by:
4 members
Upvotes:
13
Test Date:
7/8
Target GMAT Score:
760
GMAT Score:
660
Post Wed Feb 02, 2011 10:42 am
I vote C. Source please!

  • +1 Upvote Post
  • Quote
  • Flag
crimson2283 Senior | Next Rank: 100 Posts Default Avatar
Joined
07 Jan 2011
Posted:
84 messages
Upvotes:
5
Post Tue Feb 01, 2011 9:35 am
IMO C

Perhaps
(25) some of them could climb trees,
but no convincing analysis has
demonstrated how Archaeopteryx
would have both climbed and
flown with its forelimbs, and there
(30) were no plants taller than a few
meters in the environments where
Archaeopteryx fossils have been
found. --- Means the plants were very small and they could easily climb them. Perhaps these plants were taller than them.[/b]

(Many small animals, and even
some goats and kangaroos,
are capable of climbing trees
but are not gliders.) -- Here the author says that despite the fact that these plants were small, some animals did manage to climb (like the small animals)

Since the passage already states the animals were small, you should infer from the first part and undermine the author's argument.

  • +1 Upvote Post
  • Quote
  • Flag
prachich1987 Legendary Member
Joined
12 Sep 2010
Posted:
752 messages
Followed by:
10 members
Upvotes:
20
GMAT Score:
700
Post Sat Jan 29, 2011 5:12 am
+1 for D
Please post the OA along with the source

  • +1 Upvote Post
  • Quote
  • Flag
ashforgmat Senior | Next Rank: 100 Posts Default Avatar
Joined
21 Feb 2010
Posted:
71 messages
Upvotes:
3
GMAT Score:
750
Post Sat Jan 29, 2011 4:04 am
I guess its D since both C and D undermine the arboreal hypothesis but as per the passage many small animals are able to climb trees even "Goats and Kangaroos" can climb trees...hence it may be possible that small animals were able to climb trees in those times.

But as per D there were trees taller than a few metres where the fossils of arboreal ancestors have been found ...there is no other fact which undermines the short tree evidence hence IMO D beats C...

whats the OA?

  • +1 Upvote Post
  • Quote
  • Flag
AIM GMAT Legendary Member Default Avatar
Joined
25 Aug 2010
Posted:
857 messages
Followed by:
15 members
Upvotes:
56
Post Mon Jan 24, 2011 6:46 am
Both the options C and D undermine the arboreal hypothesis .

Option C says that that period had small trees , so gliding from trees isnt the option , that directly doubts the arboreal hypothesis .

Now option D says that small animals were also able to climb trees , but infact acc to C if the trees were not large enough then how wud small animals glide ?

So the degree of undermining is more for D Smile .

Hope you get my point.

_________________
Thanks & Regards,
AIM GMAT

  • +1 Upvote Post
  • Quote
  • Flag
hja379 Master | Next Rank: 500 Posts
Joined
26 Aug 2010
Posted:
208 messages
Followed by:
2 members
Upvotes:
20
Post Mon Jan 24, 2011 3:39 am
The passage mentions small animals to make a point that climbing tree alone does not equal to flying.
Goats and kangaroos might not have even existed during the period of Archaeopteryx. I don't think
choice C undermines the arboreal hypothesis.

What is the OA?

  • +1 Upvote Post
  • Quote
  • Flag

Best Conversation Starters

1 Roland2rule 174 topics
2 lheiannie07 110 topics
3 ardz24 64 topics
4 LUANDATO 56 topics
5 swerve 46 topics
See More Top Beat The GMAT Members...

Most Active Experts

1 image description Brent@GMATPrepNow

GMAT Prep Now Teacher

150 posts
2 image description Jeff@TargetTestPrep

Target Test Prep

145 posts
3 image description Rich.C@EMPOWERgma...

EMPOWERgmat

116 posts
4 image description GMATGuruNY

The Princeton Review Teacher

103 posts
5 image description Scott@TargetTestPrep

Target Test Prep

98 posts
See More Top Beat The GMAT Experts