It is cited as evidence against the claim that the capacity for flight first developed in treedwelling reptiles. It weakens the claim that tree-dwelling reptiles were the first kind of reptile to develop the capacity for flight. It is cited as evidence against the claim that the capacity for flight first developed in marine reptiles. It is cited as evidence against the claim that the capacity for flight first developed in land-dwelling animals.
Some biologists believe that the capacity for flight first developed in marine reptiles, claiming that feathers are clearly developed from scales. Other biologists rightly reject this suggestion, pointing out that bats have no scales and that nonmarine reptiles also have scales. Those who believe that flight first developed in tree-dwelling reptiles reject the claim that the limbs of land-dwelling reptiles might have developed into wings. They insist that it is more likely that tree-dwelling reptiles developed wings to assist their leaps from branch to branch.
Which one of the following most accurately describes the role played in the passage by the claim that nonmarine reptiles have scales?