Jean-Bernard Caron and colleagues recently discovered a cache of jellyfish fossils in the Burgess Shale, a site in the Canadian...
GMAT Information and Ideas : (Ideas) Questions
Jean-Bernard Caron and colleagues recently discovered a cache of jellyfish fossils in the Burgess Shale, a site in the Canadian Rockies that is rich in fossils from the Cambrian period (over 500 million years ago). Caron and colleagues claim that these are the oldest jellyfish fossils ever discovered. In the past twenty years, two sites in China and the United States have yielded fossils of a similar age that some experts believe are most likely jellyfish due to their shapes and the appearance of projecting tentacles. But Caron and colleagues argue that the apparent tentacles are in fact the comb rows of ctenophores, gelatinous animals that are only distantly related to jellyfish.
Which statement, if true, would most directly weaken the claim by Caron and colleagues about the fossils found in China and the United States?
Step 1: Decode and Map the Passage
Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "Jean-Bernard Caron and colleagues recently discovered a cache of jellyfish fossils in the Burgess Shale, a site in the Canadian Rockies that is rich in fossils from the Cambrian period (over 500 million years ago)." |
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| "Caron and colleagues claim that these are the oldest jellyfish fossils ever discovered." |
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| "In the past twenty years, two sites in China and the United States have yielded fossils of a similar age that some experts believe are most likely jellyfish due to their shapes and the appearance of projecting tentacles." |
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| "But Caron and colleagues argue that the apparent tentacles are in fact the comb rows of ctenophores, gelatinous animals that are only distantly related to jellyfish." |
|
Passage Architecture & Core Elements
Main Point: Scientists disagree about whether certain ancient fossils from China and the US are jellyfish or ctenophores, with Caron's team arguing they're ctenophores despite appearances.
Argument Flow: The passage establishes Caron's claim about having the oldest jellyfish fossils, then introduces competing fossils that challenge this claim, and concludes with Caron's rebuttal that these competing fossils aren't jellyfish at all but rather ctenophores.
Step 2: Interpret the Question Precisely
What's being asked? We need to identify which statement would most directly weaken Caron and colleagues' specific claim about the fossils found in China and the United States.
What type of answer do we need? Evidence that undermines or casts doubt on Caron's assertion that the China/US fossils are ctenophores rather than jellyfish.
Any limiting keywords? Question Characterization:
- Content Genre: Sciences
- Content Format: Text-only
- Question Type: Strengthen / Weaken
- Language Complexity: Moderate
Step 3: Prethink the Answer
- Caron's claim is that the China/US fossils are ctenophores, not jellyfish—specifically that what look like tentacles are actually comb rows
- To weaken this claim, we need something that either:
- Provides evidence they actually ARE jellyfish, or
- Shows there's insufficient evidence to confidently identify them as ctenophores
- The key insight is that Caron is making a definitive identification claim
- Any evidence that this identification is uncertain, inconclusive, or based on insufficient data would weaken his position
- This doesn't weaken Caron's claim about the China/US fossils—if anything, it confirms ctenophores existed in the fossil record
- If the fossils can't be conclusively identified as either jellyfish OR ctenophores, then Caron's confident assertion that they're ctenophores is undermined
- The absence of ctenophores in Burgess Shale doesn't prove the China/US fossils aren't ctenophores
- Better preservation of Caron's own fossils doesn't weaken his claim about what the China/US fossils are