Darwin (1897, 282) stated: “The furculum differs in being more or less arched, and greatly, as may be seen in the accompanying outlines, in the shape of the terminal plate; but the shape of this part differed in two skeletons of the wild Bankiva.” The wild G. bankiva was considered by Darwin (1897, 257) to be the extant (living) chicken progenitor (parent) of the most common domesticated chicken species.
According to Wikipedia, the furcula (which means “little fork” in Latin) is the wishbone of the bird.
After partaking of a holiday meal, my uncle always challenged me on the turkey wishbone. He would always win by finishing with the middle fused portion after we pulled. I made the mistake of pulling near the end, and this almost always resulted in a leveraged fracture in the same side I was holding, thus allowing him to win HIS wish every time!
Darwin, Charles. The variation of animals and plants under domestication, Volume I. New York: D. Appleton and Company, 1897.