While preparing a presentation on avian evolution, a student takes the following notes:
* *Microraptor gui* was a dromaeosaurid dinosaur that possessed asymmetric flight feathers on both its forelimbs and hindlimbs.
* The "ground-up" (cursorial) hypothesis proposes that flight evolved in running animals, which requires high-speed running on flat ground to generate lift.
* The "trees-down" (arboreal) hypothesis proposes that flight evolved in tree-dwelling animals that glided from elevated perches.
* Biologist Dr. Sarah Werning used aerodynamic modeling to study the effects of *Microraptor*'s long hindlimb feathers.
* The model showed that the hindlimb feathers would create excessive drag during terrestrial running but would act as stabilizing airfoils during gliding descents.
The student wants to support the claim that *Microraptor*'s physical features are more consistent with the "trees-down" hypothesis than the "ground-up" hypothesis. Which choice most effectively uses information from the notes to accomplish this goal?
- ADr. Sarah Werning used aerodynamic modeling to study *Microraptor gui*, a dromaeosaurid dinosaur that had asymmetric flight feathers on both its forelimbs and hindlimbs.
- According to aerodynamic modeling, *Microraptor*'s hindlimb feathers would have created excessive drag during the ground running required by the cursorial hypothesis but would have stabilized gliding descents from elevated perches as proposed by the arboreal hypothesis.Answer
- CBecause *Microraptor* was a dromaeosaurid dinosaur with four wings, it likely evolved from tree-dwelling ancestors that spent most of their lives in forest canopies.
- DAerodynamic modeling shows that *Microraptor*'s hindlimb feathers reduced drag during terrestrial running, which allowed the dinosaur to run fast enough to generate lift from the ground up.