《北史·列传·卷三十二》
元帝初元年间，丞相府史家的雌鸡孵化鸡雏，却渐渐变成雄鸡，长出鸡冠和距爪，并会打鸣。
元帝初元中，丞相府史家雌鸡伏子，渐化为雄，冠距鸣将。
In the first year of Chengdi's rule, there was a female chicken in the house of the assistant of the prime minister that hatched chicks, that gradually turned into a male chicken. It grew a comb and spurs, and could crow.