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Conodonts, the spiky phosphatic remains (bones and teeth composed of c

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New post 14 Jun 2017, 02:40
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Question 1
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D
E

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39% (06:55) correct 61% (03:54) wrong based on 557

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Question 2
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A
B
C
D
E

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40% (00:55) correct 60% (00:48) wrong based on 561

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D
E

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OG 2018 New RC
Line
    Conodonts, the spiky phosphatic remains (bones
    and teeth composed of calcium phosphate) of
    tiny marine animals that probably appeared about
    520 million years ago, were once among the most
(5)
    controversial of fossils. Both the nature of the
    organism to which the remains belonged and the
    function of the remains were unknown. However,
    since the 1981 discovery of fossils preserving not
    just the phosphatic elements but also other remains
(10)
    of the tiny soft-bodied animals (also called conodonts)
    that bore them, scientists' reconstructions of the
    animals' anatomy have had important implications
    for hypotheses concerning the development of the
    vertebrate skeleton.


(15)
    The vertebrate skeleton had traditionally been
    regarded as a defensive development, champions of
    this view postulating that it was only with the much
    later evolution of jaws that vertebrates became
    predators. The first vertebrates, which were soft-
(20)
    bodied, would have been easy prey for numerous
    invertebrate carnivores, especially if these early
    vertebrates were sedentary suspension feeders.
    Thus, traditionalists argued, these animals developed
    coverings of bony scales or plates, and teeth were
(25)
    secondary features, adapted from the protective
    bony scales. Indeed, external skeletons of this
    type are common among the well-known fossils of
    ostracoderms, jawless vertebrates that existed from
    approximately 500 to 400 million years ago.
(30)
    However, other paleontologists argued that many of
    the definitive characteristics of vertebrates, such as
    paired eyes and muscular and skeletal adaptations
    for active life, would not have evolved unless the
(35)
    first vertebrates were predatory. Teeth were more
    primitive than external armor according to this view,
    and the earliest vertebrates were predators.


    The stiffening notochord along the back of the
    body, V-shaped muscle blocks along the sides,
(40)
    and posterior tail fins help to identify conodonts as
    among the most primitive of vertebrates. The lack of
    any mineralized structures apart from the elements
    in the mouth indicates that conodonts were more
    primitive than the armored jawless fishes such as the
(45)
    ostracoderms. It now appears that the hard parts that
    first evolved in the mouth of an animal improved its
    efficiency as a predator, and that aggression rather
    than protection was the driving force behind the origin
    of the vertebrate skeleton.


(Book Question: 514)
According to the passage, the anatomical evidence provided by the preserved soft bodies of conodonts led scientists to conclude that
A. conodonts had actually been invertebrate carnivores
B. conodonts' teeth were adapted from protective bony scales
C. conodonts were primitive vertebrate suspension feeders
D. primitive vertebrates with teeth appeared earlier than armored vertebrates
E. scientists' original observations concerning the phosphatic remains of conodonts were essentially correct


(Book Question: 515)
The second paragraph in the passage serves primarily to
A. outline the significance of the 1981 discovery of conodont remains to the debate concerning the development of the vertebrate skeleton
B. contrast the traditional view of the development of the vertebrate skeleton with a view derived from the 1981 discovery of conodont remains
C. contrast the characteristics of the ostracoderms with the characteristics of earlier soft-bodied vertebrates
D. explain the importance of the development of teeth among the earliest vertebrate predators
E. present the two sides of the debate concerning the development of the vertebrate skeleton

(Book Question: 516)
It can be inferred that on the basis of the 1981 discovery of conodont remains, paleontologists could draw which of the following conclusions?
A. The earliest vertebrates were sedentary suspension feeders.
B. Ostracoderms were not the earliest vertebrates.
C. Defensive armor preceded jaws among vertebrates.
D. Paired eyes and adaptations for activity are definitive characteristics of vertebrates.
E. Conodonts were unlikely to have been predators.

[Reveal] Spoiler: Question #1 OA
[Reveal] Spoiler: Question #2 OA
[Reveal] Spoiler: Question #3 OA

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New post 14 Jun 2017, 03:44
i dont understand this passage
is there any lack of words in line 20?

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New post 14 Jun 2017, 09:00
Top Contributor
mbahanoi wrote:
i dont understand this passage
is there any lack of words in line 20?


The missed line added.
Thanks
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New post 29 Jun 2017, 21:09
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Please comment on answer as I have not purchased OG to double check my reasoning.

Tone: Evaluate
Organization:
P1: Describe the significance of a discovery that led to some hypotheses.
P2: Describe 2 hypotheses - traditionalists view and paleontologists view. Authors seems to favor paleotologists' view.

Topic: Discovery of fossils
Scope: Development of vetebrate skeleton based on discovery.

1. D
Uncertain between choice B and D.
B. conodonts' teeth were adapted from protective bony scales
Thus, traditionalists argued, these animals developed coverings of bony scales or plates, and teeth were secondary features, adapted from the protective bony scales.

D. primitive vertebrates with teeth appeared earlier than armored vertebrates
The lack of any mineralized structures apart from the elements in the mouth indicates that conodonts were more primitive than the armored jawless fishes such as the ostracoderms.

Remarks:
Is it always the case that the credited answer is what the author actually intends to support? I finally choose E because the whole passage are gears towards paleontologist view and traditionalists view is just for evaluation, that is, initially it was thought, then (MAIN CONCLUSION).
Furthermore, there is the word indicate which can be concluded as conclude in this case?

2. E present the two sides of the debate concerning the development of the vertebrate skeleton
Uncertain between A and E.
A. It does actually use findings to support each argument.
E. It is mainly about presenting 2 different view using the same evidence?

Remarks:
Chosen E because it encompasses 2 views and is more general.
Usually function question does not include details in the answer.

3. B. Ostracoderms were not the earliest vertebrates.
The lack of any mineralized structures apart from the elements in the mouth indicates that conodonts were more primitive than the armored jawless fishes such as the ostracoderms.

Although I have obtained all credited answer ,but I did not complete in the recommended time.

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New post 01 Jul 2017, 02:51
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The passage was easy , but the inference for question 1 was tough .
If we read passage carefully we can find the answer to this question, easily.
Reading the following lines reveals that primitive vertebrates with teeth appeared earlier than armored vertebrates
Hence D is the answer.
Teeth were more
primitive than external armor according to this view,
and the earliest vertebrates were predators.

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New post 01 Jul 2017, 04:52
how do I find information to answer the first question?

Okay, now I got it.
Lesson: right answers can be found in any paragraph.
A is too extreme because of "actually had been"
E is out because no information found
C is wrong because 1/ too extreme, not all cocodonts 2/ by definition in the first paragraph, concodont is just remains, not animals

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New post 03 Jul 2017, 03:21
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Official explanation is here https://books.google.co.in/books?id=f5v ... &q&f=false
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New post 17 Aug 2017, 19:52
[quote="anje29"]Official explanation is here

Thanks! Although I feel confused reading this OG explanation about Q1..It mainly talked about P3 when the right answer lies in P2.. [Thus, traditionalists argued, these animals developed coverings of bony scales or plates, and teeth were secondary features, adapted from the protective bony scales. ]

I may have to give up this question because I still can't find any reason to locate that answer in that position...unless you decide to look through all the passage .

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New post 25 Aug 2017, 23:42
Valhalla
your explanation is best
this cleared all my doubts thank you so much

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New post 28 Aug 2017, 09:19
Valhalla wrote:
Please comment on answer as I have not purchased OG to double check my reasoning.

Tone: Evaluate
Organization:
P1: Describe the significance of a discovery that led to some hypotheses.
P2: Describe 2 hypotheses - traditionalists view and paleontologists view. Authors seems to favor paleotologists' view.

Topic: Discovery of fossils
Scope: Development of vetebrate skeleton based on discovery.

1. D
Uncertain between choice B and D.
B. conodonts' teeth were adapted from protective bony scales
Thus, traditionalists argued, these animals developed coverings of bony scales or plates, and teeth were secondary features, adapted from the protective bony scales.

D. primitive vertebrates with teeth appeared earlier than armored vertebrates
The lack of any mineralized structures apart from the elements in the mouth indicates that conodonts were more primitive than the armored jawless fishes such as the ostracoderms.

Remarks:
Is it always the case that the credited answer is what the author actually intends to support? I finally choose E because the whole passage are gears towards paleontologist view and traditionalists view is just for evaluation, that is, initially it was thought, then (MAIN CONCLUSION).
Furthermore, there is the word indicate which can be concluded as conclude in this case?

2. E present the two sides of the debate concerning the development of the vertebrate skeleton
Uncertain between A and E.
A. It does actually use findings to support each argument.
E. It is mainly about presenting 2 different view using the same evidence?

Remarks:
Chosen E because it encompasses 2 views and is more general.
Usually function question does not include details in the answer.

3. B. Ostracoderms were not the earliest vertebrates.
The lack of any mineralized structures apart from the elements in the mouth indicates that conodonts were more primitive than the armored jawless fishes such as the ostracoderms.

Although I have obtained all credited answer ,but I did not complete in the recommended time.


Regarding Q2 :
E. present the two sides of the debate concerning the development of the vertebrate skeleton
Para 2 only present one side of the debate. The other side is presented in para 3. Then how come E is correct?

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New post 05 Sep 2017, 00:44
Hello GMATNinja sayantanc2k

For question 3, although I marked the correct option for Q3, I was confused between B and D. Can you help to explain how to eliminate option D?

It can be inferred that on the basis of the 1981 discovery of conodont remains, paleontologists could draw which of the following conclusions?
A. The earliest vertebrates were sedentary suspension feeders.
B. Ostracoderms were not the earliest vertebrates.
C. Defensive armor preceded jaws among vertebrates.
D. Paired eyes and adaptations for activity are definitive characteristics of vertebrates.
E. Conodonts were unlikely to have been predators.

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New post 05 Sep 2017, 01:08
Hey Dkingdom

The below is para 2 acc to me and hence E is correct

The vertebrate skeleton had traditionally been
regarded as a defensive development, champions of
this view postulating that it was only with the much
later evolution of jaws that vertebrates became
predators. The first vertebrates, which were soft-
(20)
bodied, would have been easy prey for numerous
invertebrate carnivores, especially if these early
vertebrates were sedentary suspension feeders.
Thus, traditionalists argued, these animals developed
coverings of bony scales or plates, and teeth were
(25)
secondary features, adapted from the protective
bony scales. Indeed, external skeletons of this
type are common among the well-known fossils of
ostracoderms, jawless vertebrates that existed from
approximately 500 to 400 million years ago.
(30)
However, other paleontologists argued that many of
the definitive characteristics of vertebrates, such as
paired eyes and muscular and skeletal adaptations
for active life, would not have evolved unless the
(35)
first vertebrates were predatory. Teeth were more
primitive than external armor according to this view,
and the earliest vertebrates were predators.

Hope this helps :-)

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New post 12 Sep 2017, 07:43
I have marked initially all correct
D, E, B

But later changed 1) to C
Reason - the answer D is palentologists view
Not the scientists
Since after line 30 was all palentologists arguing comments.

But if we find from line 43 onward what is written is answer D
Confused that it is scientists or palentologists conclusion.

If scientists then in line 19-23 whose idea was that - must be of scientists only. ???
Kindly explain me

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New post 12 Sep 2017, 07:45
And since i got all correct i am wondering like what is the difficulty level of this passage - from my guess it can be anywhere from 600-700

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New post 09 Oct 2017, 11:14
There could be a huge debate of where the 2nd passage starts and where it ends. I even looked in official guide 2018 where it can be horridly concluded that the 2nd passage end in line 29.

I just got lost and selected a wrong answer choice. I hope I don't see such instances of bad formatting in actual GMAT.
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Re: Conodonts, the spiky phosphatic remains (bones and teeth composed of c   [#permalink] 09 Oct 2017, 11:14
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