Page:The Osteology of the Reptiles.pdf/185

Rh the postaxial condyle (Figs. 135, 151). It has more of a sliding or arthrodial joint in land reptiles rotating the foot in extension. It articulates distally—primitively with the calcaneum and astragalus. Its lower end in those reptiles, especially cursorial reptiles, in which the astragalus is closely united or fused with the tibia, is obsolete or lost; in the later pterodactyls (Fig. 155 ) the whole bone has disappeared, as a separate ossification at least.