w
If you're familiar with heirloom vegetables, vegetables that were once commonly available many, many years ago, but were never grown by farmers when agriculture became industrialized, these might be considered heirloom chickens. In North America, agriculture evolved to become more about growing vegetables faster and larger to maximize profits, so only a few varieties of tomato and potato are available, for instance.
This is also true for chickens - the North American idea of what a chicken should look like is based on the only type that we raise. My idea of what a chicken looks like definitely isn't what you see here.