LSAT 151 – Section 3 – Question 12

LSAT 151 - Section 3 - Question 12

September 2018

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT151 S3 Q12
+LR
Sufficient assumption +SA
Conditional Reasoning +CondR
Link Assumption +LinkA
A
1%
147
B
95%
161
C
1%
148
D
3%
153
E
0%
140
127
135
143
 +Easier 146.292 +SubsectionMedium

A recently discovered fossil, which is believed by some to come from Archaeoraptor liaoningensis, a species of dinosaur, can serve as evidence that birds evolved from dinosaurs only if the entire fossil is from a single animal. However, the fossil is a composite of bones collected from various parts of the discovery site, so it does not provide evidence that birds evolved from dinosaurs.

Summary
The author concludes that a recently discovered fossil does not provide evidence that birds evolved from dinosaurs. Why? Because of the following:
In order for a fossil to serve as evidence that birds evolved from dinosaurs, it must be the case that the entire fossil is from a single animal.
But the recently discovered fossil is a compositive of bones collected from different parts of the discovery site.

Missing Connection
We know from the first premise that if the fossil isn’t from a single animal, then it isn’t evidence that birds evolved from dinosaurs. But do we have enough to establish that the fossil isn’t from a single animal? No — all we know from the other premise is that the fossil is a composite of bones from different parts of the discovery site. But couldn’t the bones still be from the same animal?
To make the argument valid, then, we want to prove that the fossil is not from the same animal. We can do this by establishing that if the fossil is a composite from different areas of the discovery site, it must come from more than one animal.

A
The only paleontologists who believe that the entire fossil is from a single animal are those who were already convinced that birds evolved from dinosaurs.
(A) doesn’t establish that the fossil comes from multiple animals. What scientists believe about the fossil doesn’t establish that it comes from multiple animals.
B
If the fossil is a composite, then it has pieces of more than one animal.
We know from a premise that the fossil is a composite. According to (B), then, it has pieces of more than one animal. Since the fossil isn’t just from a single animal, we can conclude that the fossil cannot serve as evidence that birds evolved from dinosaurs.
C
There are other fossils that provide evidence that birds evolved from dinosaurs.
(C) doesn’t establish that the fossil comes from multiple animals. What is true about other fossils doesn’t prove the origin of this fossil.
D
If the entire fossil is from a single animal, then it is a well-preserved specimen.
We don’t know that the fossil is NOT a well-preserved specimen. So (D) doesn’t establish that the fossil comes from multiple animals.
E
The fossil was stolen from the discovery site and sold by someone who cared much more about personal profit than about the accuracy of the fossil record.
(E) doesn’t establish that the fossil comes from multiple animals.

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LSAT PrepTest 151 Explanations

Section 1 - Reading Comprehension

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Logical Reasoning

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