OK, I was a bit lax there - and what a lot of new stuff you've given me there. I seem to remember the feather was one of the features that used to surface in creationist arguments as evidence of something that had no purpose in a form less than the fully developed flight feather.

I have been thinking of these things as members of a cohort between definitely dinosaur and definitely bird, some of which would go on to be birds, and some not. So that even if a particular species did not go on to be an ancestor, it could indicate the direction things were moving. Is that reasonable?

Penny