Critical Reasoning

The southern half of a certain region of the earth was covered entirely by water during the Cretaceous period, the last 75 million years of the Mesozoic era, the era when dinosaurs roamed the earth. Dinosaurs lived only on land. Thus, Plesiosaurs—swimming reptile that lived during the Cretaceous period exclusively—were not dinosaurs. No single species of dinosaur lived throughout the entire Mesozoic era.
If the statements in the passage are true, each of the following could be true EXCEPT:
(A) Dinosaurs inhabited the northern half of the region throughout the entire Mesozoic era.
(B) Plesiosaurs did not inhabit the southern half of the region during the Cretaceous periods.
(C) Plesiosaurs did not inhabit the southern half of the region before the Cretaceous period.
(D) Dinosaurs did not inhabit the northern half of the region during the Cretaceous period.
(E) Dinosaurs inhabited the southern half of the region throughout the entire Mesozoic era.

E, through process of elimination

Ans E .
Negates the fact.

The fact is No single species of dinosaur lived throughout the entire Mesozoic era
and E says Dinosaurs inhabited the southern half of the region throughout the entire Mesozoic era.

lvincy wrote:Ans E .
Negates the fact.

The fact is No single species of dinosaur lived throughout the entire Mesozoic era
and E says Dinosaurs inhabited the southern half of the region throughout the entire Mesozoic era.

That's not the reason E is wrong. The stem says no single species lived throughout the entire era, not that Dinosaurs couldn't be alive during that time.


E says that Dinosaurs inhabited the southern half of the region...

But we know two things from the stem: 1) The southern half of a certain region of the earth was covered entirely by water and 2) Dinosaurs lived only on land.

So there could not have been any Dinosaurs living in the southern region during the Cretaceous era (which was part of the Mesozoic era).

Stem:
1,Cretaceous - all water cover, 75 m years
2,Cretaceous belongs to Mesozic
3,Dinosaurs live on land
4,Plesiosaurs live in water

A, OK, the northern maybe not cover by water in the Cretaceous period
B, ??? conflict with 1 and 4
C, OK, because before Cretaceous, the south is not cover by water
D, ??
E, Conflict with the stem that no Dinosaur can live through entire Meso
I chose B, Howerver, E also seems correct,
How can elimimate the fault one?

NSNguyen wrote:The southern half of a certain region of the earth was covered entirely by water during the Cretaceous period, the last 75 million years of the Mesozoic era, the era when dinosaurs roamed the earth. Dinosaurs lived only on land. Thus, Plesiosaurs—swimming reptile that lived during the Cretaceous period exclusively—were not dinosaurs. No single species of dinosaur lived throughout the entire Mesozoic era.
If the statements in the passage are true, each of the following could be true EXCEPT:
(A) Dinosaurs inhabited the northern half of the region throughout the entire Mesozoic era.
(B) Plesiosaurs did not inhabit the southern half of the region during the Cretaceous periods.
(C) Plesiosaurs did not inhabit the southern half of the region before the Cretaceous period.
(D) Dinosaurs did not inhabit the northern half of the region during the Cretaceous period.
(E) Dinosaurs inhabited the southern half of the region throughout the entire Mesozoic era.

IMO (C)
---------

However, I feel that this question is wrong.

What is OA?

This question is fine and (E) is definitely the answer.

As always, let's start by making sure that we understand the question:

If the statements in the passage are true, each of the following could be true EXCEPT

Here we have a variation of an inference question.

In an inference question we're looking for a statement that MUST BE TRUE based on one or more of the sentences in the stimulus.

In this question, we're looking for a "could be true EXCEPT". In other words, the 4 wrong answers all "could be true" and the correct answer "MUST be false". So, we're looking for the choice that contradicts one or more of the statements in the stimulus.

The only choice that's contradictory is (e):

Dinosaurs inhabited the southern half of the region throughout the entire Mesozoic era.

From the stimulus, we know that:

(1) The southern half of a certain region of the earth was covered entirely by water during the Cretaceous period, the last 75 million years of the Mesozoic era; and

(2) Dinosaurs lived only on land.

From these two facts, we can deduce with certainty that:

(3) Dinosaurs did not live in the southern half of the region during the last 75 million years of the Mesozoic era.

Accordingly, (e) MUST be false.

No one listens to me when I say it.

Stuart Kovinsky wrote:This question is fine and (E) is definitely the answer.

As always, let's start by making sure that we understand the question:

If the statements in the passage are true, each of the following could be true EXCEPT

Here we have a variation of an inference question.

In an inference question we're looking for a statement that MUST BE TRUE based on one or more of the sentences in the stimulus.

In this question, we're looking for a "could be true EXCEPT". In other words, the 4 wrong answers all "could be true" and the correct answer "MUST be false". So, we're looking for the choice that contradicts one or more of the statements in the stimulus.

The only choice that's contradictory is (e):

Dinosaurs inhabited the southern half of the region throughout the entire Mesozoic era.

From the stimulus, we know that:

(1) The southern half of a certain region of the earth was covered entirely by water during the Cretaceous period, the last 75 million years of the Mesozoic era; and

(2) Dinosaurs lived only on land.

From these two facts, we can deduce with certainty that:

(3) Dinosaurs did not live in the southern half of the region during the last 75 million years of the Mesozoic era.

Accordingly, (e) MUST be false.

egybs wrote:No one listens to me when I say it.

I was listening! I promise!

I feel the answer is D.

Below are reasons for not E :

From the stimulus, we know that:

(1) The southern half of a certain region of the earth was covered entirely by water during the Cretaceous period, the last 75 million years of the Mesozoic era; and

note: only a certain region was filled with water and not all so assuming that whole south was in water is awry .


(2) Dinosaurs lived only on land.

note : when only a part of southern earth is in water , there are chances of dinos roaming in the land available

From these two facts, we can deduce with certainty that:

(3) Dinosaurs did not live in the southern half of the region during the last 75 million years of the Mesozoic era.

Based on the above notes I feel we have wrongly assumed that southern earth was under water in that period thereby E cant be said to be false.

(D) Dinosaurs did not inhabit the northern half of the region during the Cretaceous period.

There is no proof in the stimulus to say that dinos did not inhabit the northern half ,that clearly says that D is false and as per the stimulus dinos did inhabit the northern half of the region during the era inturn the Cretaceous period too.



Please experts have a relook into this reasoning and let me know if I am wrong


thanks
senthil

please note : Moreover it is mentioned only a species of dino dint live for long not the whole dino itself

Hi Stuart,

It is still confusing. Please see the attached image for the break up of period of Mesozoic Era.

Here is the explanation from my side.

As we know we have to eliminate all those statements that are either BE TRUE or COULD BE TRUE. So, let's analyze each statement one by one.

(A) Dinosaurs inhabited the northern half of the region throughout the entire Mesozoic era.
It COULD BE TRUE. See point 5 of RED region of the attached image. So it may Dinos were present only during Cretaceous Period.

(B) Plesiosaurs did not inhabit the southern half of the region during the Cretaceous periods.
It is TRUE. See point 3 of RED region of the attached image.

(C) Plesiosaurs did not inhabit the southern half of the region before the Cretaceous period.
It COULD BE TRUE. See point 3 of YELLOW region of the attached image. As Plesiosaurs lived in water, so it might be only Northern half of earth could be covered with water before the Cretaceous Period.

(D) Dinosaurs did not inhabit the northern half of the region during the Cretaceous period.
It COULD BE TRUE. See point 5 of RED region of the attached image. Might be Dinos were not present during The Cretaceous period because they might not be exist at time. If dino were extinct by that time, then this statement could be true.

(E) Dinosaurs inhabited the southern half of the region throughout the entire Mesozoic era.
It COULD BE TRUE. See point 5 of RED region and point 3 of YELLOW region of the attached image. Might be Dinos were not present during The Cretaceous period because they might not be exist at time. If dino were extinct by that time and before Createaceous Period only the Northern half of earth is covered with water, then this statement could also be true.

oooh, this is definitely a very annoying question!

I am also going with E. To me, no single species means none of the dinosaurs...just as we say "not one single person came to xyz," it means no one came to xyz.

The other answers are possible.

Honestly, I'm not sure why this is so confusing!

(d) talks about the northern part of the region. We have absolutely no info about the norther half of the region. So, we have no clue if dinosaurs lived there during the Cretaceous. Accordingly, (d) may be true OR it may be false: elminate (d).

(e) on the other hand 100% contradicts the facts we're given.

Dinosaurs only live on land.

For a certain period of time, the southern half of the region was under water.

Therefore, dinosaurs didn't live in the southern half of the region while it was under water and (e) is impossible.

Don't read more into the statements than is explicitly stated. Accept the statements in the stimulus (i.e. the passage) as true - don't argue with them. Look for the answer that 100% contradicts one or more of those statements.

Don't see the confusion here either... This is a really straight forward question..... certainly don't think it warrants dino2.png!

E is the right answer... but that's not why!

Your analogy is incorrect. A more similar sentence would be the following:

"No single human was alive between 1800 and 2000."

It doesn't mean that humans didn't live during that period of time! It simply means that no individual was alive for those 200 years.

newera wrote:oooh, this is definitely a very annoying question!

I am also going with E. To me, no single species means none of the dinosaurs...just as we say "not one single person came to xyz," it means no one came to xyz.

The other answers are possible.