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- Fri Jan 21, 2011 12:00 am
#23507
Complete Question Explanation
Assumption. The correct answer choice is (D)
The stimulus here is making a logical mistake common in the LSAT — because we have not found evidence of something, it did not occur. Here, the assumption being made is that since we have not found any dromeosaur fossils older than the oldest bird fossils, dromeosaurs could not preceded the oldest birds. What this argument fails to consider is the possibility that there are older dromeosaur fossils that have yet to be found or that have been destroyed. The assumption answer choice must therefore defend the stimulus against this possible argument.
Answer Choice (A): While this answer choice definitely supports the stimulus argument, it is not an assumption upon which the argument depends.
Answer Choice (B): If anything, this answer choice increases the connection between dromeosaurs and birds and helps the paleontologist's argument that the stimulus is disputing.
Answer Choice (C): This answer choice seems close to what we are looking for, but it fails to consider that even if the knowledge of bird and dromeosaur fossils is complete, there could still have been dromeosaurs older than the oldest birds. Perhaps the dromeosaurs died in a way that left behind no fossils or the fossils were destroyed sometime after their death.
Answer Choice (D): This is the correct answer choice. If we use the assumption negation technique and state that known fossils do not indicate the relative date of origin of birds and dinosaurs, then the stimulus argument is attacked. If the fossils of both do not paint a complete picture, we can no longer use the fact that known bird fossils are older than known dromeosaur fossils to refute the paleontologists claim.
Answer Choice (E): The mere fact that dromeosaurs and birds are dissimilar in many ways does not refute the claim that birds descended from dromeosaurs. Many descendants are very different than the things they descended from.
Assumption. The correct answer choice is (D)
The stimulus here is making a logical mistake common in the LSAT — because we have not found evidence of something, it did not occur. Here, the assumption being made is that since we have not found any dromeosaur fossils older than the oldest bird fossils, dromeosaurs could not preceded the oldest birds. What this argument fails to consider is the possibility that there are older dromeosaur fossils that have yet to be found or that have been destroyed. The assumption answer choice must therefore defend the stimulus against this possible argument.
Answer Choice (A): While this answer choice definitely supports the stimulus argument, it is not an assumption upon which the argument depends.
Answer Choice (B): If anything, this answer choice increases the connection between dromeosaurs and birds and helps the paleontologist's argument that the stimulus is disputing.
Answer Choice (C): This answer choice seems close to what we are looking for, but it fails to consider that even if the knowledge of bird and dromeosaur fossils is complete, there could still have been dromeosaurs older than the oldest birds. Perhaps the dromeosaurs died in a way that left behind no fossils or the fossils were destroyed sometime after their death.
Answer Choice (D): This is the correct answer choice. If we use the assumption negation technique and state that known fossils do not indicate the relative date of origin of birds and dinosaurs, then the stimulus argument is attacked. If the fossils of both do not paint a complete picture, we can no longer use the fact that known bird fossils are older than known dromeosaur fossils to refute the paleontologists claim.
Answer Choice (E): The mere fact that dromeosaurs and birds are dissimilar in many ways does not refute the claim that birds descended from dromeosaurs. Many descendants are very different than the things they descended from.