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

Question 2
(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

I was down to B and D and ended up choosing B because I thought that the 2nd passage end in line 29.
How can we eliminate option B here? Please help.

The paleontologists argued that these are definitive features of a vertebrate. This argument is not derived from the discovery of condonants, but by general belief of scientists.

Can someone explain the third question? I got it right, but I spent almost 3 mins on this one. I had difficulties in locating where should I refer to answer this question.

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.
DPaired eyes and adaptations for activity are definitive characteristics of vertebrates.
E Conodonts were unlikely to have been predators.

I found the discovery in p1 and p3. p1 just states that the discovery changes the views scientists hold about the development of vertebrate animals. p3 seems talk about the discovery(in a vague and subtle way, there is no obvious link between the discovery talked about in p1)

Cheers!

A closer look at Question #3

Your approach to this question was sound! It's a legitimately tough question, and difficult to answer without a clear read on the passage structure and process of elimination.


The only place this discovery is explicitly mentioned is in P1, but (as you know) this isn't a situation where there's some immediate factoid that we see directly connected to the year 1981. Instead, we see this big-picture statement:

"However, since the 1981 discovery of fossils preserving not just the phosphatic elements but also other remains 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."

This doesn't point us to something that happened in 1981. Instead, the significance of this line is why the author brings up this discovery: To call into question the existing hypotheses about why the vertebrate skeleton evolved.

OK, so let's think about this structurally. P1 tells us that the conodont discovery set up scientists (and us, the readers) to reconsider two hypotheses. P2 is all about presenting those hypotheses (which existed prior to the discovery and did not use conodonts as evidence), so we're not going to find the answer there.

But the purpose of P3 is to tell us that the hypothesis of aggressive evolution seems to be correct. And P3 delivers this statement based on the discovery of conodont remains:

"The stiffening notochord...V-shaped muscle blocks...and posterior tail fins help to identify conodonts as among the most primitive of vertebrates. The lack of any mineralized structures...indicates that conodonts were more primitive than the armored jawless fishes such as the 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."

All right! The 1981 discovery triggered a new debate over the origin of the vertebrate AND placed conodonts as one of the earliest examples of vertebrate evolution being driven by aggression.

Let's start eliminating:

Sedentary suspension feeders were mentioned in P2 as potential evidence for vertebrate evolution being defensive. It's a thing that was mentioned in the passage, but it's not a statement that we can infer on the basis of the 1981 discovery of conodont remains. Eliminate (A).


This looks good! P3 specifically tells us that conodonts were vertebrates AND were more primitive than ostracoderms. This would imply that Ostracoderms were not the earliest vertebrates, because they were predated by conodonts. Let's keep choice (B) around and keep moving.


Nope. Like choice (A), this is not a statement that we can infer on the basis of the 1981 discovery of conodont remains. It's a tempting choices, but we can eliminate (C) just like we eliminated (A).


Like (A) and (C), this choice is tempting but it's not a fact that we can infer on the basis of the 1981 discovery. Eliminate (D).


Choice (E) is totally off the rails (off the spine?). The entire point of P3 is that conodonts were evolved to be predators. This is the opposite of what this choice says, so let's eliminate (E), too.

(B) is the only choice that directly answers the question and is backed up by our understanding of the 1981 discovery's importance.

I hope this helps clarify how to stay ahead of this question! Whether or not it increases your appreciation of conodonts is up to you. I do hear rumors that they taste like chicken...
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The arrogance of Indians in the RC sub-thread blows my mind.

Look at the stats buddy - they tell a different story.

I personally got all correct, but I found this to be one of the more challenging passages.

(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 - in the passage it said, teeth came first
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
Second paragraph clearly was presenting the traditional view and the new view
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.

I have an issue with Question 516. I believe you have to understand what the word primitive means to get the correct answer. I thought primitive meant basic so I saw relatively little importance with that fact. However, for question 516, choice B is 100% right if you realize primitive means first/ancient which supports the answer choice that Ostracoderms were not the earliest vertebrates. Just my two cents but I'd be happy to hear if others would comment on this.

Hi,

For 3rd question why option E is not the correct answer?

There's a detailed explanation of question #3 here: https://gmatclub.com/forum/conodonts-th ... l#p2179425. Let us know if that doesn't resolve your doubts.
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Question 2 - Please explain the difference between B & D. Dont they say the same thing? GMATNinja

dear experts,

how can i get the last paragraph links to the discovery?
what i can get is
1/ tranditional view is happerened before discovery because the tense is past perfact, while the discovery is simple past, so i think tranditional view is happened before the discovery
2/ i initially thought the paleontologists' view comes from the discovery, and the last paragraph states the author's view, but when i read the post wholely, i found it's not the case, so i reread the passage, i am still cannot figure out the clue that can link the discovery and views .

please help~~~
i am worried about my read comprehension

Take a look at the detailed explanation in this post and let me know whether you have lingering doubts!


The structure of the passage can help clear up any questions about how the timeline fits together:

• Paragraph 1: We learn that there is a controversy surrounding conodonts, and that a 1981 discovery had "important implications" regarding this controversy
• Paragraph 2: The author explains both sides of the controversy, with evidence for each side from BEFORE the 1981 discovery (for a more detailed break down, please see this post). The point at issue is whether the vertebrate skeleton was first developed for defense or for predation.
• Paragraph 3: The author states that "it NOW appears... that aggression rather than protection was the driving force behind the origin of the vertebrate skeleton."

In chronological order, this is what happened:

• Paleontologists had two competing theories regarding conodonts
• A discovery was made in 1981
• This discovery supported one of the theories over the other

By using the word "now" in the third paragraph, the author makes it clear that the information is current -- so, it is from AFTER the 1981 discovery. In addition, we can infer that the support for one of the theories presented is the "important implication" that resulted from the 1981 discovery, as discussed in paragraph 1.

I hope that helps!
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Hi GMATNinja,

Thank you for the very clear explanation. Everything makes perfect sense, except for the way the question is phrased "According to the passage, the anatomical evidence provided by the preserved soft bodies of conodonts led scientists to conclude that"

They talked about the PRESERVED SOFT BODIES, of conodonts, which I couldn't find anywhere. That whole paragraphs talked about the preserved remains of soft-bodied animals, not preserved soft bodies (which I don't think is possible either since soft bodies have no fossils, they would just debiograde): However, since the 1981 discovery of fossils preserving not just the phosphatic elements but also other remains of the tiny soft-bodied animals (also called conodonts) that bore them,

How can I make sense of this wording of the question? May I also ask what exactly do they mean "also called conodonts"? The remains of the tiny-soft bodied animals are also called conodonts, or just the tiny soft-bodied animals are called conodonts? The very first lines seemed to refer to conodonts as remains, not the animals. So what exactly do they mean by conodonts here, and "the preserved soft bodies of conodonts"?

Please help Thank you very much!

Two different things in the passage are referred to as "conodonts":

1) "the spiky phosphatic remains (bones and teeth composed of calcium phosphate) of tiny marine animals"; AND
2) "tiny soft-bodied animals (also called conodonts)"

So, the word "conodont" refers to BOTH the phosphatic remains of certain tiny animals, and to the tiny animals themselves.

In 1981, scientists discovered fossils that preserved both the phosphatic and "other" remains of the tiny animals. These additional remains were, in fact, softer tissues, including a "notochord along the back of the body, V-shaped muscle blocks along the sides, and posterior tail fins." (Side note: soft tissues can indeed be fossilized -- read about dinosaur soft-tissue fossilization here. Apparently it is uncommon for soft tissues of land-dwellers to be fossilized unless the animal "suffer[s] a rare catastrophic burial -- such as death by landslide." Good stuff.)

Question #1 asks about the "preserved soft bodies of conodonts," which we know to be the fossils discovered in 1981.

I hope that clears it up!
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Same thing.....
tradTionalists labelled tHem as DEFENSIVE and after 1981, they were labelled as AGGRESSIVE.

it was this point that brought about the 'contrast' for me.
but then i do realize i was wrong....just because an opinion changes 180 degrees does not mean its a contrast.

i REALLY wd like examples of contrasts tho....

Hi AbdurRakib, GMATNinja

what should be the time line to finish this passage? I got it completed in about 15 mins with one wrong. Took me lots of effort to not dwell in the detail but stick to the structure.

this is hard
understanding passage is hard. at first, author talks about discovery, then about two views and at the end, about implication of the discovery.. the second paragraph dose not mention the discovery. this is hard for us to understand. only in the third paragraph, author said the discovery confirm the new view.

so, quesion 1 and 3 are easy if we understand the structure of the passage
question 2 is tricky. choice b is tricky. the new view is not derived from the discovery. the discovery confirm the new view in the third paragraph.
I miss question 2. I can not find out the wrong phrase "view derived from..."
when considering an answer choice, try to find, at least, a wrong word in the choice to eliminate. never expect that prethinking an answer and matching it with an answer choice is good.

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







Can someone help me with Q2…?
E present the two sides of the debate concerning the development of the vertebrate skeleton
I’m stuck between B and E.

Sb explain thus….
Chosen E because it encompasses 2 views and is more general.
Usually function question does not include details in the answer.

please see the picture in the attachment....OG's explanation



In OG, the explanation just says that ‘the second paragraph does not explicitly
indicate whether the opposition to the traditional view originally rested on the 1981 discovery of conodont remains……it just turn out to support the opposing view ’
sb also wrote in the forum
'because an opinion changes 180 degrees does not mean its a contrast.'......

but we see in line(30) the author use ‘however’…isn’t this a ‘contrast…’???

or maybe we can explain in this way
para2 contrast ‘traditional view’ with ‘some paleontologist’s view’, and these paleontologist’s view not necessarily must be the view of ‘1981 discovery of conodont remains’…..????

The second paragraph does not explicitly indicate whether the opposition to the traditional view originally rested on the 1981 discovery of conodont remains.