Flight Ability of Winged Creatures from Fossil Record

So, it occurred to me: if chickens (and some other birds) have wings but cannot fly, what reasons have we to believe that fossilized creatures with wings could fly? I guess this question hasn't any radical implications, but was just something I started wondering about for no good reason.The kind of evidence we would need, I suppose, would be of such creatures living in high places that would not be easily reached by non-flying creatures. Perhaps a certain diet would prove something”flying birds eat fish, for example, while flightless birds do not. There are other potential evidences, but these are just some examples.Anyone know anything about this?
Thanks,
Jon Edited by Gremled the Great, : No reason given.Edited by Jon, : No reason given.Edited by Jon, : Changed 'dinosaurs' to 'fossilized winged creatures'

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Sorry folks for my incorrect and uninformed posting. I have edited the topic slightly to more match my original intentions. More generally, I am wondering if there is any evidence from winged creatures in the fossil record that shows they could use their wings.In 12 million years when they dig up a chicken fossil and eagle fossil, how will they know one could use its wings for all-out flight, and the other just just for slowing a fall? What is different or happens differently in winged creatures who fly that would preserve itself as evidence of their flying ability?Thanks,
JonEdited by Jon, : No reason given.

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