Chamaeleonidae

Chamaeleonidae View in CoL View at ENA ( Figs 49C, D View Figure 49 , 50E, F View Figure 50 )

Chamaeleo chamaeleon has a stocky compound bone made up of completely fused surangular, prearticular and articular, whereas the angular is unfused. The latter ( Fig. 49C, D View Figure 49 ) has a pointed anterior end and enlarges posteriorly, bending in dorsolateral direction. It is concave in the dorsal direction in its anterior portion, whereas it is straighter in the posterior one. A foramen opens in the anterior direction on the dorsomedial surface of the bone, roughly at midlength. The surangular and prearticular portions of the compound bone are clearly recognizable as distinct branches separated by a notch where the inferior posterior process of the dentary inserts ( Fig. 50E, F View Figure 50 ). Because of the presence of this notch, the latter process contributes to the formation of the lateral wall of the adductor fossa. No expansions are present, neither on the surangular branch nor on the prearticular one. The surangular branch is the shortest one and has a large recess that can be seen in anterior view: this is the posterior continuation of the recess of the dentary. Both the medial and lateral surfaces of this branch are smooth, except for the anterior portion of the latter, which has the articulation surface with both the superior posterior process of the dentary and the posterior process of the coronoid. The anterior surangular foramen is not visible in lateral view. The prearticular branch is twice as long as the surangular one. It is straight and houses the posterior portion of the Meckel’s cartilage in a deep dorsal channel. It also presents a wide groove for the articulation with the angular on the ventrolateral surface. The articular condyle is strongly dorsally concave ( Fig. 50E View Figure 50 ). The retroarticular process is not present, but the medial surface of the bone can have a moderately small tubercle in the position of the angular process ( Fig. 50E View Figure 50 ).