No proof, just a working knowledge of genetics.And why do you say that? Out of curiosity, do you have proof?
Boiled down, Chickens and birds has drastically different structures, Avian birds such as robins, sparrows, parrots, pigeons etc are hatched helpless for the parent pigeons to raise, Fowl such as, turkeys, chickens, quail, emu, ducks etc are hatched ready to go, and we've seen that hybrids among avian birds with avian birds and fowl with fowl. (birds in the same genus)
Even if an egg was 'fertilized' (even in the case of inter genus hybrids, there's very slim chances of viable offspring) it is highly unlikely that the chick would make it to hatch and if it did, would live only briefly.
I think a bantam with a fan tail or has the crown from a Victorian Crowned would be really neat, but unfortunatly it's just not possible.