"The chain of evolutionary development..." How do you know there is one?
The evidence for evolution isn't secret, it's easy to find. This is one of the most secure theories in the whole of science - the only controversy surrounding it is artificially generated by religious fundamentalists. The science is as solid as it gets.
The scale to feather hypothesis is not a good one, from what I've read.
It wouldn't matter a jot if there wasn't any direct evidence for scale to feather. It wouldn't be as much as a grain of sand out of the mountain of evidence for evolution.
It's the increase in complexity, from microscopic to great big, that I have a problem with. Not minor variation like claw types or feather types. You can line up a group of species and demonstrate an evolutionary progression, based on comparative anatomy or geological context. You can equally conclude, based on the many examples of stasis in the fossil record, that evolution only exists within boundaries such as genus or family.
Except that wouldn't actually explain the all evidence of the fossil record. And again,
genetics alone gives us enough evidence for common descent. It was a
dramatic confirmation of what had been deduced from the other evidence - including the fossil record, of course.
And yet again, if you're talking about YEC, evolution is only one of the many sciences that falsify it.