Or, maybe.... it's a squirrel that is evolving a different appendage, as opposed to a "new" appendage. What I mean is that this species is coded for so much more than it's current expression of DNA. If it is evolving a wing, then the DNA code for this wing already exists. I would like to see some evolutionists try to artificially select for tentacle-like structures to replace it's tail. How much time do you need?