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Re: Raptors climbing trees?

Graydon wrote ( in part)

How do you tell the adaptation from the exaption? Especially initially?<

The answer is that you can infer exaptation, but you can observe adaptation. An exaptation is the opportunistic use by an animal of a preexisting characteristic that enhances its ability to produce offspring in a changing environment. If that characteristic is selectively spread by natural selection through a population over time, it is seen in the fossil record as an evolutionary adaptation. Given the resolution of the fossil record it is, I think, unreasonable to expect to see isolated exaptation events, but not at all unreasonable to see, as we have, the spread of a preferentially adaptive characteristic through a population over time.