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Difficulty: Very hardCross-Text Connections: Perspective Comparison

Text 1

Paleontologist Dr. Helena Rostova posits that the initial evolutionary driver of avian flight feathers was strictly thermoregulatory. Rostova argues that the filamentous structures on non-avian theropods served primarily to retain metabolic heat in high-latitude environments, and that their subsequent modification into asymmetric, aerodynamic shapes occurred only after these lineages occupied ecological niches requiring gliding. According to Rostova, any aerodynamic utility in early, symmetrical proto-feathers was purely incidental and insufficient to drive selection, as the physical force generated by such structures during cursorial movement would have been negligible for propulsion.

Text 2

Conversely, evolutionary biologist Dr. Julian Thorne contends that proto-feathers on theropod forelimbs were selected for their aerodynamic utility during cursorial (ground-running) locomotion long before gliding behavior emerged. Thorne points to biomechanical simulations indicating that even symmetric, proto-feathered forelimbs would have generated significant aerodynamic drag and lift during high-speed running, aiding in stabilization, braking, and steep-slope ascent. Consequently, Thorne asserts that thermoregulation was a secondary, co-opted benefit rather than the primary evolutionary catalyst, suggesting that the physiological demands of locomotion shaped proto-feather development from the outset.

Based on the texts, how would Dr. Julian Thorne (Text 2) most likely characterize the claim in Text 1 that symmetrical proto-feathers provided negligible aerodynamic utility during cursorial movement?

  1. A
    As a valid point that highlights why thermoregulation must have been the sole driver of proto-feather selection until gliding emerged.
  2. As an assertion that is contradicted by biomechanical evidence demonstrating that symmetric proto-feathers could assist running theropods with maneuvers other than direct forward propulsion.Answer
  3. C
    As a claim supported by simulations showing that drag and lift forces are only generated by modern, asymmetric feathers.
  4. D
    As a plausible hypothesis that could be verified by examining the fossilized remains of theropods from high-latitude environments.

Answer

As an assertion that is contradicted by biomechanical evidence demonstrating that symmetric proto-feathers could assist running theropods with maneuvers other than direct forward propulsion.
The correct answer is correct because Text 1 claims that the aerodynamic utility of symmetrical proto-feathers during running would be 'negligible for propulsion.' In Text 2, Dr. Julian Thorne challenges this by referencing biomechanical simulations that indicate symmetric proto-feathers generated significant drag and lift, which aided in stabilization, braking, and climbing. Therefore, Thorne would view the claim in Text 1 as an assertion that is contradicted by biomechanical evidence showing these feathers assisted running theropods with maneuvers other than direct forward propulsion.

Step-by-Step Solution

1
Identify the specific claim in Text 1 mentioned in the prompt.
In Text 1, Dr. Helena Rostova claims that the aerodynamic utility of symmetrical proto-feathers was negligible for propulsion during ground running.
Locating and understanding the target claim is essential before evaluating the opposing author's response.
2
Examine Text 2 to identify Dr. Julian Thorne's counter-perspective and evidence.
In Text 2, Dr. Julian Thorne references biomechanical simulations showing that symmetric proto-feathers generated significant drag and lift that aided running theropods in stabilization, braking, and steep-slope ascent.
This details the specific evidence and reasoning Thorne uses to counter Rostova's view on symmetric feathers.
3
Synthesize how Thorne would characterize Rostova's claim.
Thorne would argue that Rostova's focus on 'propulsion' overlooks the significant aerodynamic benefits of stabilization, braking, and ascent revealed by simulations, thus characterizing her claim as contradicted by biomechanical evidence.
Comparing the two arguments leads to the correct matching statement.

Key Concept

Cross-Text Connections: Perspective Comparison
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Cross-Text Connections: Perspective Comparison

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