A recent study has provided clues to predator-prey dynamics in the lat

1. A. Last paragraph implies that if the prey was scarce then the predator had more contact with the prey's bone.
2. B 5th line of the 2nd paragraph states this.
3. D The last few lines of paragraph 2 points to this. The rest of the options were all dismissed by the scientists.
4. D The premise of rejecting the hypothesis of not enough older samples breaks if this option were true. If the method of identifying younger from older was faulty and identified older dinos as younger, then there were clearly more older dinos among the samples under study.
5. A If either or both of those samples had breakage, then it would be possible that there was some damage done by the pits that stored the fossils for all of these years.
6. A Last paragraph says that prey was "seasonally available". Therefore, there were periods when prey was more available and periods when there was few or maybe none.

P.S. Question 5 has been repeated twice. The count of questions is 7 when in fact there are only 6 unique questions.

5. According to the passage, if the researchers had NOT found that two extinct carnivore species were free of tooth breakage, the researchers would have concluded that
A. the difference in breakage frequencies could have been the result of damage to the fossil remains in the La Brea pits
B. the fossils in other Pleistocene sites could have higher breakage frequencies than do the fossils in the La Brea pits
C. Pleistocene carnivore species probably behaved very similarly to one another with respect to consumption of carcasses
D. all Pleistocene carnivore species differed behaviorally from present-day carnivore species
E. predator densities during the Pleistocene era were extremely high

"The explanation they consider most plausible is behavioral differences between extinct and present-day carnivores"
So if the tooth -breakage problem was not there then they would have considered that Pleistocene carnivore species probably behaved very similarly to one another.
I dont understand why A.

ALso The primary purpose of the passage is to

A. present several explanations for a well-known fact

E. discuss the implications of a research finding

Implication discussion is just a part of the entire passage so why not A. Because passage explore finding, then method and then implication.

Interesting passage . Took 9 mins 50 seconds ,including 2 mins and 50 seconds to read
-The author does not provide an opinion
- He is only concerned with providing information on predator-prey dynamics
- The author presents various explanations for a finding

1 .
The author is concerned with the implications of the findings which is suggested in the following lines.. "Such thorough carcass consumption implies to the researchers either that prey availability was low, at least seasonally, or that there was intense competition over kills and a high rate of carcass theft due to relatively high predator densities "
Hence option (E) is the right answer.

2 .
"They ruled out local bias because breakage data obtained from other Pleistocene sites were similar to the La Brea data"
The above excerpt suggests that both carnivores had similar breakage patterns and thereby similar frequency in tooth fractures. Hence option (B) is the right answer.

3.
"The explanation they consider most plausible is behavioral differences between extinct and present-day carnivores—in particular, more contact between the teeth of predators and the bones of prey due to more thorough consumption of carcasses by the extinct species."
Answer D

4.
the methods used to determine animals’ ages in fossil samples tend to misidentify many older individuals as younger individuals

Answer D

5.
"They rejected preservational bias because a total absence of breakage in two extinct species demonstrated that the fractures were not the result of abrasion within the pits."
Answer A

6.
Such thorough carcass consumption implies to the researchers either that prey availability was low, at least seasonally, or that there was intense competition over kills and a high rate of carcass theft due to relatively high predator densities.

Answer A

That carcasses were consumed thoroughly is the research finding. The passage discusses what this finding might imply. Therefore E is correct.

Nowhere in the passage is stated that tooth fracture is a well-known fact. Hence option A is wrong.

Time taken 8 minutes 20 seconds 1 wrong

4. The researchers’ conclusion concerning the absence of demographic bias would be most seriously undermined if it were found that
A. the older an individual carnivore is, the more likely it is to have a large number of tooth fractures
B. the average age at death of a present-day carnivore is greater than was the average age at death of a Pleistocene carnivore
C. in Pleistocene carnivore species, older individuals consumed carcasses as thoroughly as did younger individuals
D. the methods used to determine animals’ ages in fossil samples tend to misidentify many older individuals as younger individuals
E. data concerning the ages of fossil samples cannot provide reliable information about behavioral differences between extinct carnivores and present-day carnivores

Chose B got thrown off by thinking D is out of scope. Remember to read full answer choice and don't get baited/ sold on B.

D is correct

I feel there is serious flaw in the question 5 itself

5. According to the passage, if the researchers had NOT found that two extinct carnivore species were free of tooth breakage, the researchers would have concluded that

A. the difference in breakage frequencies could have been the result of damage to the fossil remains in the La Brea pits

passage part concerning to above question

They rejected preservational bias because a total absence of breakage in two extinct species demonstrated that the fractures were not the result of abrasion within the pits.

This additional word "tooth" in the question is enough to confuse completely while understanding question itself.

Hi Shivikaa,



For Q3) This whole passage is talking about tree rings and how climatic variations affect those rings.
so 1)dendrochronologists' failure to consider the prevalence of erratic weather patterns-- we are not discussing about any prevalence of erratic weather conditions here.(Wrong)
2)inconsistencies introduced because of changes in methodology--We never discussed any particular methodology here(wrong)
3)some tree species' tendency to deviate from the norm.(Wrong)
4)the lack of detectable variation in trees with complacent rings--This is mentioned in the paragraph, but uncertainties here referring more with climatic conditions and variation in rings, this statement just tells about the variation in rings due to water supply .
5)the lack of perfect correlation between the number of a tree's rings and its age---due to climatic conditions.so this is correct.
see in the last line of the paragraph where author mentioned "when growth halts temporarily and then starts again." when this happens we cant really say what is tree's age.its not consistent.

Hope this is clear.

Thanks

Refer to this portion: "The explanation they consider most plausible is behavioral differences between extinct and present-day carnivores—in particular, more contact between the teeth of predators and the bones of prey due to more thorough consumption of carcasses by the extinct species." The passage specifically talks about contact between teeth of predators and the bones OF PREY, not between teeth of predators and the bones OF OTHER CARNIVORES during fights over kills. Thus, (E) should be eliminated, and (D) is the best choice.

As for question 4, refer to this portion: "the researchers dismissed demographic bias because older individuals were not over represented in the fossil samples." We can infer that demographic bias has to do with age differences. More specifically, if all of the fossils were from OLDER individuals, then the high proportion of tooth fractures might simply be a result of the aging process . In other words, in order to accurately compare the fossil teeth to the teeth of present-day predators, we need samples representing all ages in both groups.

With that in mind, let's consider the choices:

3mins 21 secs for 6 ques + reading passage => I am feeling jealous by your reading speed -> indeed i have seen your posts in other RC with fastest time -> generally 3m21s we take for only solving

I am just imagining your speed of going thru RC passage and then questions -> snapshot memory

2. According to the passage, compared with Pleistocene carnivores in other areas, Pleistocene carnivores in the La Brea area

(A) included the same species, in approximately the same proportions
(B) had a similar frequency of tooth fractures
(C) populated the La Brea area more densely
(D) consumed their prey more thoroughly
(E) found it harder to obtain sufficient prey


Hi GMATNinja

Can you please help in eliminating option D for Q2.

I selected D based on the highlighted part.

The explanation they consider most plausible is behavioral differences between extinct and present-day carnivores—in particular, more contact between the teeth of predators and the bones of prey due to more thorough consumption of carcasses by the extinct species.Such thorough carcass consumption implies to the researchers either that prey availability was low,

The piece of the passage that you've highlighted shows a difference between present day carnivores and extinct carnivores. Take another look at question #2:

This is a different comparison than the one in your analysis -- question #2 asks us to compare Pleistocene carnivores in the La Brea area with Pleistocene carnivores in other areas. In other words, we need to compare carnivores that lived in the same time frame, but in different locations.

Here is the relevant piece of the passage to make that comparison:

This tells us that Pleistocene carnivores in multiple locations had similar tooth fractures. This aligns nicely with answer choice (B), which states that the carnivores in different locations "had a similar frequency of tooth fractures." (B) is the correct answer for question #2.

Answer choice (D) tells us that Pleistocene carnivores in the La Brea area "consumed their prey more thoroughly" than Pleistocene carnivores in other areas. Because we know from the passage that tooth breakage data were consistent across multiple locations, we cannot conclude that this is true. Eliminate (D).

I hope that helps!

In Q1, I got stuck between option A and E; Could someone clarify why E is correct?

Can someone quote where author is discussing the implications of research finding ?

I believe author is explaining well known fact why "The breakage frequencies in the extinct species were strikingly higher than those in the present-day species." in whole passage. Hence option A should be correct.

GMATNinja, VeritasKarishma, DmitryFarber, kindly help

Given the first para where the author starts with a recent finding and go onto describe that finding which is: "A recent study has provided clues to predator-prey dynamics in the late Pleistocene era. Researchers compared the number of tooth fractures in present-day carnivores with tooth fractures in carnivores that lived 36,000 to 10,000 years ago and that were preserved in the Rancho La Brea tar pits in Los Angeles. The breakage frequencies in the extinct species were strikingly higher than those in the present-day species.

In the second para, the author is gradually taking out all the biases and drawing the conclusion implied based on these findings. Also, the author intended to elaborate the findings' implication: "Such thorough carcass consumption implies to the researchers either that prey availability was low, at least seasonally, or that there was intense competition over kills and a high rate of carcass theft due to relatively high predator densities."


Hope that helps!

Kudos if helpful

Question 1 asks what is the primary purpose of the passage. For (A) to be the correct answer, we would need to see a well-known fact in the passage.

The "fact" presented at the end of the first paragraph tells us "The breakage frequencies in the extinct species were strikingly higher than those in the present-day species." but we can hardly say this fact is well-known -- it is a result from the recent study described at the start of the passage.

Also, the passage does not present several explanations. The researchers "reject", "dismiss", or "rule out" several explanations in the second paragraph, before discussing the ONE explanation for their research finding that is most plausible.

(A) is out.

The start of the second paragraph discusses possible explanations for findings of the recent study before stating:

This part of the paragraph discusses the implications of the research finding given at the end of the first paragraph.

So, overall, in this passage the author:

• Introduces a research finding
• Rejects a bunch of potential explanations for this finding
• Discusses a more plausible explanation, and the implications of that explanation

From this breakdown, we can say that the author's purpose in writing the passage was to "discuss the implications of a research finding." (E) is the correct answer to question 1.

I hope that helps!

1. The primary purpose of the passage is to

In the opening line of the first paragraph, we have "A recent study has provided clues..." the second paragraph then builds on the implications of the new findings. (E) captures this thought perfectly.

(E) discuss the implications of a research finding

Hence, (E) is the right answer choice.

2. According to the passage, compared with Pleistocene carnivores in other areas, Pleistocene carnivores in the La Brea area

Towards the middle of the second paragraph, we have "breakage data obtained from other Pleistocene sites were similar to the La Brea data." This would imply that the data from the two sites had to be similar to each other. This thought is captured in (B).

(B) had a similar frequency of tooth fractures

Hence, (B) is the right answer to this question.


3. According to the passage, the researchers believe that the high frequency of tooth breakage in carnivores found at La Brea was caused primarily by

Towards the end of the second paragraph, we have "more contact between the teeth of predators and the bones of prey due to more thorough consumption of carcasses". This is what we have in (D).

(D) the impact of carnivores’ teeth against the bones of their prey

Hence, (D) is the right answer choice.

4. The researchers’ conclusion concerning the absence of demographic bias would be most seriously undermined if it were found that

In the beginning of the second paragraph, we have "dismissed demographic bias because older individuals were not over represented in the fossil samples"

(D) the methods used to determine animals’ ages in fossil samples tend to misidentify many older individuals as younger individuals - what (D) tells us is that many ''younger individuals'' were misidentified; In fact, these misidentified younger individuals were actually ''older individuals''. So, this would imply that the fossils did contain a disproportionately larger presence of older individuals than younger ones, thereby weakening the reasoning provided to reject demographic bias. Hence, (D) is the right answer choice.

5. According to the passage, if the researchers had NOT found that two extinct carnivore species were free of tooth breakage, the researchers would have concluded that

To answer this question, let us first understand what implications did this ''finding'' have on the research.

The second paragraph is constructed to explain why " The breakage frequencies in the extinct species were strikingly higher than those in the present-day species."

Towards the middle of the second paragraph, we have "They rejected preservational bias because a total absence of breakage in two extinct species demonstrated that the fractures were not the result of abrasion within the pits". In other words, the researches rule out the possibility of the ''teeth fractures'' appearing as a result of any other process than the teeth-to bone contact.

Now, if these two extinct carnivore species (found in the La Brea tar pits in Los Angeles) did have tooth breakage, then one could presume that the all fossils found in the pits will contain tooth breakage.

Hence, it will be impossible to rule out the possibility that the teeth breakage would be caused by some sort of damage to these fossils while these fossils were preserved in the pits. (In other words, if the entire sample of fossils obtained have teeth breakage, then it becomes that much more difficult to point out a particular reason/source for the teeth breakage observed). This thought is perfectly captured in (A).

(A) the difference in breakage frequencies could have been the result of damage to the fossil remains in the La Brea pits

Hence, (A) is the right answer choice.

6. The passage suggests that tooth fractures in Pleistocene carnivores probably tended to occur less frequently

In the second paragraph, it is established that ''thorough consumption'' is what eventually led to higher teeth breakage frequency. If in any case the ''breakage frequency'' is lower than usual, then it must imply that thorough consumption did not take place.

From the passage, we can infer that shortage of prey is what led to thorough consumption. So, it is possible that an abundance of prey could lower the chances of thorough consumption and hence ''teeth breakage frequency''. Therefore, tooth fractures in Pleistocene carnivores probably tended to occur less frequently when there was an abundance of prey. This is what we have in (A).

(A) during periods in which more prey were available

Hence, (A) is the right answer choice.

I believe for 5th question, option B is the correct the correct answer as it creates a bias.

Please can elaborate more here why B here is rejected and A is accepted.