Talking about dark meat, it contains a higher constituent of myoglobin. This myoglobin is found in the muscle cells as a biologic pigment, and it provides oxygen to the body during physical exertion such as exercise. This myoglobin is found more at the leg of walking birds like chickens and turkeys than another part of their bodies.
Thus, good examples of dark meat are the legs of these birds. Dark meat has more vitamin B and other minerals like iron and zinc. On the other hand, white meat has fewer calories compared to dark meat.
Also, when it comes to the fat content in white meat, it is still less than that of dark meat. Many actually choose white meat above dark meat for this reason, but dark meat has more nutrients than white meat. Though the legs of birds like turkey and chicken are a good source of dark meat, the other parts of the birds are a better source of white meat.