We were in the area near "chicken park" and came across a huge handsome fellow with a massive butterfly comb. (Chicken park is an area in the city where people sadly dump their unwanted birds. Naturally the population is 90% roosters.) Not sure what breed he was but looked a little like a Bielfelder or similar. It got me wondering about comb genetics. He did not look like he had any apparent Houdan and was very large. Are there other breeds with these "double" combs? If he was a mutt, what would the likely origins of that comb be? It was very impressive and made him look positively prehistoric. Any good sources discussing comb genetics for a beginner?