The paleontologist never mentions the ornithologist’s qualifications. Rather, the paleontologist questions whether the ornithologist’s evidence is sufficient, based on the example of a modern bird.

The paleontologist does not deny that curved claws enable birds to perch in trees, nor does he deny that Archeopteryx also had curved claws and could perch in trees. He just denies that this evidence is enough to show that Archeopteryx was a tree-dwelling bird.

This accurately describes the paleontologist's argument. The parallel case the paleontologist uses is the case of chickens, which can also perch in trees--implying they have curved claws--but are primarily ground-dwelling birds. The paleontologist uses this example to undermine the ornithologist's assumption that the claw curvature shared between modern tree-dwelling birds and Archeopteryx is enough to establish that Archeopteryx was a tree-dwelling bird. Chickens also share this trait of curved claws, but aren't tree-dwelling.

The paleontologist does not claim that the ornithologist’s hypothesis contradicts the evidence offered in support of it. Rather, the paleontologist claims that the ornithologist’s evidence is not sufficient to support the hypothesis: the fact that modern tree-dwelling birds have curved claws, and Archeopteryx also had curved claws, isn't enough to establish that Archeopteryx was tree-dwelling.

The paleontologist does not support the ornithologist’s argument. The evidence the paleontologist provides--the example of chickens--is not meant to support the ornithologist's conclusion, but to show that the ornithologist’s evidence isn't sufficient to support that conclusion.