Fig. 5

Comparative view of the head of a normal Appenzeller Barthuhn chicken with an animal with crossed beaks. Macerated bones of the beak of a control chicken (a + b) and a chicken with crossed beak (c + d). Volume rendered three-dimensional computed tomographic model of the normal head of a control (e + f) and of a crossed beak (g + h): view from dorsal (e + g) and ventral (f + h). Note that both upper and lower beak of the crossed beak are bent to the right. Os praemaxillare (pm) of the maxilla with processus maxillaris (1), processus palatinus (2), processus frontalis (3), and the os nasale (n). Mandibula with pars caudalis (4), pars intermedia (5), and pars symphysialis (6)