Text 1
Some paleontologists argue that avian flight evolved from the 'ground up' (the cursorial hypothesis). They contend that cursorial theropod dinosaurs, running along the ground to escape predators or capture prey, began using proto-wings to generate lift and stability, eventually leading to powered flight. They point to the skeletal morphology of early theropods, which suggests powerful hindlimbs adapted for rapid running rather than climbing.
Text 2
Other researchers argue that the cursorial model is aerodynamically implausible. They maintain that avian flight emerged from the 'trees down' (the arboreal hypothesis), in which tree-dwelling ancestors of birds glided from branches and gradually developed flapping flight to control their descent. According to these scientists, the energetic cost of achieving takeoff from a flat, running start would have been too high for primitive theropods lacking advanced flight musculature.
Based on the passages, how would the author of Text 2 most likely respond to the claim in Text 1 that early theropods developed flight while running along the ground?
- ABy agreeing that hindlimb morphology indicates early theropods were physically incapable of climbing trees.
- BBy arguing that running theropods used proto-wings exclusively to defend themselves against predators.
- By asserting that the physiological energy required to achieve takeoff from the ground would have been prohibitive for these creatures.Cevap
- DBy suggesting that powered flight evolved immediately without an intermediate gliding phase.