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# Dinosaur expert: Some paleontologists have claimed...

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Dinosaur expert: Some paleontologists have claimed...  [#permalink]

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21 Nov 2014, 07:17
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49% (01:58) correct 51% (02:00) wrong based on 682 sessions

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Dinosaur expert: Some paleontologists have claimed that birds are descendants of a group of dinosaurs called dromeosaurs. They appeal to the fossil record, which indicates that dromeosaurs have characteristics more similar to birds than do most dinosaurs. But there is a fatal flaw in their argument; the earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils. Thus the paleontologists' claim is false'.
The expert's argument depends on assuming which one of the following?
(A) Having similar characteristics is not a sign that types of animals are evolutionarily related.
(B) Dromeosaurs and birds could have common ancestors .
(C) Knowledge of dromeosaur fossils and the earliest bird fossils is complete.
(D) Known fossils indicate the relative dates of origin of birds and dromeosaurs.
(E) Dromeosaurs are dissimilar to birds in many significant ways.
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Dinosaur expert: Some paleontologists have claimed...  [#permalink]

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21 Nov 2014, 21:30
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1
Gmat1008 wrote:
Dinosaur expert: Some paleontologists have claimed that birds are descendants of a group of dinosaurs called dromeosaurs. They appeal to the fossil record, which indicates that dromeosaurs have characteristics more similar to birds than do most dinosaurs. But there is a fatal flaw in their argument; the earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils. Thus the paleontologists' claim is false'.
The expert's argument depends on assuming which one of the following?
(A) Having similar characteristics is not a sign that types of animals are evolutionarily related.
(B) Dromeosaurs and birds could have common ancestors .
(C) Knowledge of dromeosaur fossils and the earliest bird fossils is complete.
(D) Known fossils indicate the relative dates of origin of birds and dromeosaurs.
(E) Dromeosaurs are dissimilar to birds in many significant ways.

Here was my thought process for the question:

Stem lists assumption, so look for SUPPORTER or DEFENDER assumptions based on the stimulus.

Stimulus notes: The expert argues that the paleontologists are wrong in their claim that dromeosaurs are similar to birds BECAUSE the bird fossils are much much older than dromeosaur fossils. A big gap in the expert's thinking, therefore, is that he/she is thinking that the time gap is the reason for the paleontologists flaw in reasoning. This was the major gap that popped out on my first reading of the stimulus.

A - This assumption is not the crux of the expert's counterargument to the paleontologists. Nothing in the stimulus suggests that the expert disagrees with the similarity of characteristics.
B - The expert is actually assuming the OPPOSITE of this answer. The paleontologists are making this assumption. Remember, there are two different viewpoints in this question.
C - At first glance this might make sense - all the fossils have been collected and the expert can now draw his conclusion. However, try negating this answer choice. Knowledge of dromeosaur fossils and the earliest bird fossils is NOT complete. This does not weaken the expert's conclusion severely. At this point, though, you could hold on to this answer choice as a contender.

D - This is correct - The argument refers to fossils that have been found, and that the time difference between the fossils can somehow invalidate the relationship between birds and dromeosaurs. As a test, try negating it: Known fossils DO NOT indicate the relative dates of origin of birds and dromeosaurs. The expert would not be able to substantiate his/her claim now; if fossils didn't indicate the dates of their existence, then the paleontologists theories could not be disputed.
E - The expert doesn't assume or attack the paleontologists claim of differences in the species, just the time difference of the fossils.

---
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Re: Dinosaur expert: Some paleontologists have claimed...  [#permalink]

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02 Mar 2016, 09:36

I chose 'A' as my answer because paleontologists reached to the conclusion, based on fossil record, that B and D are related after finding similar characteristic in them.

Dinosaur expert disagree with paleontologist.

Can't 'A' by the assumption that similar characteristics doesn't mean B and D are evolutionary related. Even if we negate the statement, it breaks down expert's conclusion.

I did'nt get why 'D' is the answer. What is the fossils have relative dates of origin? Does that mean B and D can't be related? Nothing in support of this is present in the argument.
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Re: Dinosaur expert: Some paleontologists have claimed...  [#permalink]

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02 Mar 2016, 11:02
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I chose 'A' as my answer because paleontologists reached to the conclusion, based on fossil record, that B and D are related after finding similar characteristic in them.

Dinosaur expert disagree with paleontologist.

Can't 'A' by the assumption that similar characteristics doesn't mean B and D are evolutionary related. Even if we negate the statement, it breaks down expert's conclusion.

I did'nt get why 'D' is the answer. What is the fossils have relative dates of origin? Does that mean B and D can't be related? Nothing in support of this is present in the argument.

Lets try -

Quote:
Dinosaur expert: Some paleontologists have claimed that birds are descendants of a group of dinosaurs called dromeosaurs. They appeal to the fossil record, which indicates that dromeosaurs have characteristics more similar to birds than do most dinosaurs. But there is a fatal flaw in their argument; the earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils. Thus the paleontologists' claim is false'.

Dinosaur expert's claim that birs are descendants of a group of dinosaurs called dromeosaurs is proved by -
Quote:
fossil record, which indicates that dromeosaurs have characteristics more similar to birds than do most dinosaurs.

But the flaw with the reasoning of the Dinosaur expert is -
Quote:
earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils.

Bird fossils =====tens of millions of years======dromeosaur fossils.

If Bird fossils> dromeosaur fossils{ Bird fossils existed before fossils of dromeosaur fossils } then the argument put forward by the Dinosaur expert is flawed.

Our argument here completely relies on the fossils of birds vs dromeosaur.

Now go through options (A) and (D) { Not going through all the options }

(A) Having similar characteristics is not a sign that types of animals are evolutionary related.

The stimulus presented to us talks about the fossil record to prove that the Dinosaur expert's reasoning is fasle. The author proves the fact by the use of the relative dates of origin of birds and dromeosaurs fossils in support of his reasoning.

Similar characteristics may be a sign of evolutaionary impact of birds/dromeosaurs but may we can not be 100% certain about it because the author uses scientific methods { dating fossils of birds and dromeosaurs }

(D) Known fossils indicate the relative dates of origin of birds and dromeosaurs.

Try to negate this option.

Known fossils do not indicate the relative dates of origin of birds and dromeosaurs.

If fossil records do not indicate the relative dates of origin of birds and dromeosaurs then the argument put forward by the author falls apart.

Hence IMHO (D)

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Re: Dinosaur expert: Some paleontologists have claimed...  [#permalink]

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03 Mar 2016, 10:23
1
Abhishek009 wrote:

I chose 'A' as my answer because paleontologists reached to the conclusion, based on fossil record, that B and D are related after finding similar characteristic in them.

Dinosaur expert disagree with paleontologist.

Can't 'A' by the assumption that similar characteristics doesn't mean B and D are evolutionary related. Even if we negate the statement, it breaks down expert's conclusion.

I did'nt get why 'D' is the answer. What is the fossils have relative dates of origin? Does that mean B and D can't be related? Nothing in support of this is present in the argument.

Lets try -

Quote:
Dinosaur expert: Some paleontologists have claimed that birds are descendants of a group of dinosaurs called dromeosaurs. They appeal to the fossil record, which indicates that dromeosaurs have characteristics more similar to birds than do most dinosaurs. But there is a fatal flaw in their argument; the earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils. Thus the paleontologists' claim is false'.

Dinosaur expert's claim that birs are descendants of a group of dinosaurs called dromeosaurs is proved by -
Quote:
fossil record, which indicates that dromeosaurs have characteristics more similar to birds than do most dinosaurs.

But the flaw with the reasoning of the Dinosaur expert is -
Quote:
earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils.

Bird fossils =====tens of millions of years======dromeosaur fossils.

If Bird fossils> dromeosaur fossils{ Bird fossils existed before fossils of dromeosaur fossils } then the argument put forward by the Dinosaur expert is flawed.

Our argument here completely relies on the fossils of birds vs dromeosaur.

Now go through options (A) and (D) { Not going through all the options }

(A) Having similar characteristics is not a sign that types of animals are evolutionary related.

The stimulus presented to us talks about the fossil record to prove that the Dinosaur expert's reasoning is fasle. The author proves the fact by the use of the relative dates of origin of birds and dromeosaurs fossils in support of his reasoning.

Similar characteristics may be a sign of evolutaionary impact of birds/dromeosaurs but may we can not be 100% certain about it because the author uses scientific methods { dating fossils of birds and dromeosaurs }

(D) Known fossils indicate the relative dates of origin of birds and dromeosaurs.

Try to negate this option.

Known fossils do not indicate the relative dates of origin of birds and dromeosaurs.

If fossil records do not indicate the relative dates of origin of birds and dromeosaurs then the argument put forward by the author falls apart.

Hence IMHO (D)

Loved the detailed explanation, and I really appreciate this effort.

However, one more query on the statement- 'earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils.' - is that isn't it states the difference between the time of discovery of these fossils? Now the possibility is that bird's fossils were discovered first (tens of millions of year before D's fossils) or dremosaur's fossils were discovered first (bird's fossils were discovered tens of millions of year after D's fossil). The statement doesn't tell us that which fossil was discovered first.

Is there any gap in my understanding?
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Re: Dinosaur expert: Some paleontologists have claimed...  [#permalink]

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03 Mar 2016, 10:44
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Loved the detailed explanation, and I really appreciate this effort.

However, one more query on the statement- 'earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils.' - is that isn't it states the difference between the time of discovery of these fossils? Now the possibility is that bird's fossils were discovered first (tens of millions of year before D's fossils) or dremosaur's fossils were discovered first (bird's fossils were discovered tens of millions of year after D's fossil). The statement doesn't tell us that which fossil was discovered first.

Is there any gap in my understanding?

Ok lets try it again ( with a different approach as well )

The main point here is

Quote:
earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils.

The underlined part : date back tens of millions of years farther than the oldest known dromeosaur fossils.

I get 2 interpretations (about the time of discovery of the fossils)-

1. Bird fossils> dromeosaur fossils - { Bird fossils were discovered prior to discovery of dromeosaur fossils }
2. dromeosaur fossils> Bird fossils - { dromeosaur fossils were discovered prior to discovery of Bird fossils}

Further we have a very crucial piece of information presented in the stimulus -

Quote:
the earliest bird fossils that have been discovered .........

The above sentence states that the time of discovery of the fossils ( Whether Bird fossils were discovered first or dromeosaur fossils ) is not important to us , the stimulus clearly states that in the time line of the fossils Bird fossils precceds dromeosaur fossils.

Elucidating further -

Say Bird fossils ( Dated to be 10,000 year old ) were discovered in the year 2000 , but dromeosaur fossils ( Dated to be 6,000 year old )were discovered in 1987.
Though dromeosaur fossils were discovered prior to the discovery of the Bird fossils, it is the bird fossils that existed prior to dromeosaur fossils.

Thats my understanding from the stimulus, I guess this questions needs further discussion....
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Re: Dinosaur expert: Some paleontologists have claimed...  [#permalink]

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16 Nov 2016, 23:35
Abhishek009 wrote:

I chose 'A' as my answer because paleontologists reached to the conclusion, based on fossil record, that B and D are related after finding similar characteristic in them.

Dinosaur expert disagree with paleontologist.

Can't 'A' by the assumption that similar characteristics doesn't mean B and D are evolutionary related. Even if we negate the statement, it breaks down expert's conclusion.

I did'nt get why 'D' is the answer. What is the fossils have relative dates of origin? Does that mean B and D can't be related? Nothing in support of this is present in the argument.

Lets try -

Quote:
Dinosaur expert: Some paleontologists have claimed that birds are descendants of a group of dinosaurs called dromeosaurs. They appeal to the fossil record, which indicates that dromeosaurs have characteristics more similar to birds than do most dinosaurs. But there is a fatal flaw in their argument; the earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils. Thus the paleontologists' claim is false'.

Dinosaur expert's claim that birs are descendants of a group of dinosaurs called dromeosaurs is proved by -
Quote:
fossil record, which indicates that dromeosaurs have characteristics more similar to birds than do most dinosaurs.

But the flaw with the reasoning of the Dinosaur expert is -
Quote:
earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils.

Bird fossils =====tens of millions of years======dromeosaur fossils.

If Bird fossils> dromeosaur fossils{ Bird fossils existed before fossils of dromeosaur fossils } then the argument put forward by the Dinosaur expert is flawed.

Our argument here completely relies on the fossils of birds vs dromeosaur.

Now go through options (A) and (D) { Not going through all the options }

(A) Having similar characteristics is not a sign that types of animals are evolutionary related.

The stimulus presented to us talks about the fossil record to prove that the Dinosaur expert's reasoning is fasle. The author proves the fact by the use of the relative dates of origin of birds and dromeosaurs fossils in support of his reasoning.

Similar characteristics may be a sign of evolutaionary impact of birds/dromeosaurs but may we can not be 100% certain about it because the author uses scientific methods { dating fossils of birds and dromeosaurs }

(D) Known fossils indicate the relative dates of origin of birds and dromeosaurs.

Try to negate this option.

Known fossils do not indicate the relative dates of origin of birds and dromeosaurs.

If fossil records do not indicate the relative dates of origin of birds and dromeosaurs then the argument put forward by the author falls apart.

Hence IMHO (D)

Can you please explain how you eliminated C?
I picked C because if the knowledge of the fossils is not complete there is a possibility that there are fossils that can substantiate Paleontologists claim .
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Re: Dinosaur expert: Some paleontologists have claimed...  [#permalink]

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01 Dec 2016, 07:18
Premise: Some paleontologists have claimed that birds are descendants of a group of dinosaurs called dromeosaurs.
Premise: They appeal to the fossil record, which indicates that dromeosaurs have characteristics more similar to birds than do most dinosaurs.
Premise: But there is a fatal flaw in their argument; the earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils.
Conclusion: Thus the paleontologists' claim is false'.

DROMEOSAURS--------------------BIRDS
SAME CHARACTERISTICS…………………..
This is not true……………………………….. BECAUSE BIRDS FOSSILS OLDER THAN DROMEOSAURS
According to the argument, now Dromeosaurs become descendants of birds.
The data on fossils is correct and there is no error.
(A) Having similar characteristics is not a sign that types of animals are evolutionarily related.
Incorrect. Negated statement supports the argument.

(B) Dromeosaurs and birds could have common ancestors.

They could have but that is not the point of discussion in this argument. Incorrect.

(C) Knowledge of dromeosaur fossils and the earliest bird fossils is complete.
If the knowledge is not complete then the conclusion no longer makes sense.

(D) Known fossils indicate the relative dates of origin of birds and dromeosaurs.
We do not want to know the exact date to support the conclusion. Incorrect.

(E) Dromeosaurs are dissimilar to birds in many significant ways.
OUT OF SCOPE.
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Re: Dinosaur expert: Some paleontologists have claimed...  [#permalink]

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24 Mar 2017, 07:44
Hi Expert,

The last posts in this thread have left the quetion still open to discussion and I request you to kindly provide a conclusive explanation. As per my understanding:

PREMISE: the earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils.
CONCLUSION: Thus the paleontologists' claim is false'.

Now option D is a restatement of the premise. IMHO I find C to be more relvant.
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Re: Dinosaur expert: Some paleontologists have claimed...  [#permalink]

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