Fig. 2

Examples of typical crossed beak in Appenzeller Barthuhn chickens. Note that the beaks are bent in different directions and at a different location. a Dorsal view on an upper beak bent to the left at the base of the beak. b Dorsal view of an upper beak bent only at the tip, while the lower beak is bent at the base with an inwardly-rolled tomium. c Ventral view of a lower beak bent at the base. d Ventral view of a lower beak bent at the tip and an upper beak bent at the base