Chamaeleonidae

Villa, Andrea & Delfino, Massimo, 2019, A comparative atlas of the skull osteology of European lizards (Reptilia: Squamata), Zoological Journal of the Linnean Society 187 (3), pp. 828-928 : 875

Chamaeleonidae

Bones of the braincase of Chamaeleo chamaeleon do not fuse. The region is roughly as long as it is wide. The foramen magnum is suboval and slightly laterally compressed and the basioccipital does not participate in its formation ( Fig. 35 ). The occipital condyle is composed mainly by otooccipitals, but a small portion of the posterior end of the basioccipital is also part of it ( Fig. 35 ). The three portions of the condyle do not fuse together. The recessus scalae tympani is strongly reduced, being visible only with a foramen on the otooccipital. Because of this, the basioccipital forms the ventral wall of the cochlear cavity. The ventral margin of the very wide fenestra ovalis is consequently composed of the sphenooccipital tubercles. The portion of margin made by the latter is small, because of the presence of two expansions of the prootic and the otooccipital that almost excludes them. The medial wall of the cochlear cavity is poorly ossified and, therefore, the cavity is open on the medial side. Semicircular canals are moderately narrow and poorly recognizable.

Figures

Figure 35. Posterior view of an articulated skull of Chamaeleo chamaeleon (MNHN 1887-875), showing the otooccipital portions (oc) of the occipital condyle excluding the basioccipital portion (b) from the margin of the foramen magnum. Scale bar = 1 mm.