Figure 3

Bill shape of the three Corvus species used in the analysis of bill structure.

(A) The head of a NCC. (B) The skull of NCC 2. (C) The skull of Rook 2. (D) The skull of LaC 1. Arrows indicate the approximate position of the nasal-frontal hinge where the upper mandible joins the cranium. Dots on the upper mandible show the edges of the nasal openings. On the lower mandible they indicate the rostral edge of the Fenestra rostralis (at right) and the gonydeal angle where the rami join at the posterior end of the keel. Length differences between the three skulls indicate actual differences (the distance from the nasal-frontal hinge to the tip of the upper mandible for NCC 2 = 4.3 cm long, for Rook 2 = 4.9 cm and for LaC 1 = 6.0 cm).