Von Mises stress for different loading conditions (LC) for 13 Darwin’s finches (PB: physiological base biting; PT: physiological tip biting; FB: base biting scaled to fortis; FT: tip biting scaled to fortis).

Model input forces (= muscle forces) for jugal (Fj) and palatine (Fp) are given in N. von Mises stresses are given in MPa for three positions indicated in Fig 1 (vM1: on top of bone, near bite position; vM2: on top of the nasal hinge; vM3: nasal bone ipsilateral side for base biting, both sides for tip biting). Gray values in CT-stack for the same positions are given (0 black, 1 white). The resulting (model) biting force (F)is given in N; the volume of keratin and bone (Vker and Vbone) are given in mm3.Von Mises stress for different loading conditions (LC) for 13 Darwin’s finches (PB: physiological base biting; PT: physiological tip biting; FB: base biting scaled to fortis; FT: tip biting scaled to fortis).