For many years, the only existing fossil evidence of mixopterid eurypterids-an extinct family of large aquatic arthropods known as sea...
GMAT Information and Ideas : (Ideas) Questions
For many years, the only existing fossil evidence of mixopterid eurypterids-an extinct family of large aquatic arthropods known as sea scorpions and related to modern arachnids and horseshoe crabs-came from four species living on the paleocontinent of Laurussia. In a discovery that expands our understanding of the geographical distribution of mixopterids, paleontologist Bo Wang and others have identified fossilized remains of a new mixopterid species, Terropterus xiushanensis, that lived over 400 million years ago on the paleocontinent of Gondwana.
According to the text, why was Wang and his team's discovery of the Terropterus xiushanensis fossil significant?
The fossil constitutes the first evidence found by scientists that mixopterids lived more than 400 million years ago.
The fossil helps establish that mixopterids are more closely related to modern arachnids and horseshoe crabs than previously thought.
The fossil helps establish a more accurate timeline of the evolution of mixopterids on the paleocontinents of Laurussia and Gondwana.
The fossil constitutes the first evidence found by scientists that mixopterids existed outside the paleocontinent of Laurussia.
Step 1: Decode and Map the Passage
Part A: Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "For many years, the only existing fossil evidence of mixopterid eurypterids—an extinct family of large aquatic arthropods known as sea scorpions and related to modern arachnids and horseshoe crabs—came from four species living on the paleocontinent of Laurussia." |
|
| "In a discovery that expands our understanding of the geographical distribution of mixopterids," |
|
| "paleontologist Bo Wang and others have identified fossilized remains of a new mixopterid species, Terropterus xiushanensis, that lived over 400 million years ago on the paleocontinent of Gondwana." |
|
Part B: Passage Architecture & Core Elements
Main Point: Wang's discovery of a mixopterid fossil on Gondwana expands our understanding beyond the previously limited evidence from Laurussia.
Argument Flow: The passage establishes that mixopterid evidence was geographically limited to one paleocontinent, then presents Wang's discovery of a new species on a different paleocontinent, showing this discovery's significance lies in expanding the known geographical range of these creatures.
Step 2: Interpret the Question Precisely
What's being asked? Why Wang's discovery was significant according to the text
What type of answer do we need? The specific reason the text gives for the discovery's importance
Any limiting keywords? "According to the text" - we must stick to what's explicitly stated, and "significant" - we need the importance/meaning of the discovery
Step 3: Prethink the Answer
- The significance must relate to the contrast between "only existing fossil evidence...came from four species living on...Laurussia" and the new discovery on Gondwana
- The passage explicitly states this discovery "expands our understanding of the geographical distribution"
- The key breakthrough is finding mixopterids somewhere other than Laurussia for the first time
The fossil constitutes the first evidence found by scientists that mixopterids lived more than 400 million years ago.
✗ Incorrect
- Claims this was the first evidence they lived more than 400 million years ago
- The passage mentions the age but doesn't suggest this was the first evidence of that timeframe
- The significance is about geography, not age
The fossil helps establish that mixopterids are more closely related to modern arachnids and horseshoe crabs than previously thought.
✗ Incorrect
- Claims it establishes relationship to modern arachnids and horseshoe crabs
- The passage already states this relationship as established fact in the opening
- The discovery's significance isn't about taxonomic relationships
The fossil helps establish a more accurate timeline of the evolution of mixopterids on the paleocontinents of Laurussia and Gondwana.
✗ Incorrect
- Claims it helps establish evolution timeline on both paleocontinents
- The passage doesn't discuss evolutionary timelines or comparative evolution
The fossil constitutes the first evidence found by scientists that mixopterids existed outside the paleocontinent of Laurussia.
✓ Correct
- States this was the first evidence of mixopterids outside Laurussia
- Perfectly matches the passage's contrast: "only existing fossil evidence...came from...Laurussia" vs. new discovery "on the paleocontinent of Gondwana"
- Aligns with the stated significance of expanding "geographical distribution"