Biplot of the first two axes of linear discriminant analysis, illustrating variation in the pedal proportions among the principal pterodactyloid clades and the three pterodactyloid track morphotypes. Shaded hulls represent morphospace occupied by pedal anatomy of pterodactyloid body fossil groups. Black hull outlines represent extent of pterosaur track morphotypes. Blue circles, track morphotype 1; green squares, track morphotype 2; orange triangles, track morphotype 3. Metatarsal length is positively associated with both axis 1 and axis 2. Proximal digit length is positively associated with axis 1 and negatively associated with axis 2. Distal digit length shows a negative association with both axis 1 and axis 2. Relative arrow lengths represent the contribution of each region to the class separation in the reduced-dimensional space. Abbreviations: DD, distal digit segment; MT, metatarsal; PD, proximal digit segment. SeeFigures S1S4andData S1for more details.
