Anguidae

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 : 879

Anguidae ( Fig. 34)

Anguids have a braincase that is slightly longer than wide, and is provided with a broad and subcircular or subelliptical foramen magnum.The portions of occipital condyle composed by the otooccipitals are reduced compared to the portion composed by the basioccipital. The posterior margin of the condyle is not notched, but convex ( Anguis gr. An. fragilis ; Fig. 34D, E) or straight ( Pseudopus apodus ; Fig. 34I, J), in dorsal and ventral views. The recessus scalae tympani is moderately reduced in Anguis gr. An. fragilis ( Fig. 34B), but larger in Pseudopus apodus ( Fig. 34G). It opens externally with an anteroposteriorly elongated lateral opening that is narrow in Anguis gr. An. fragilis ( Fig. 34B). The medial opening of the recessus scalae tympani is wide and, in Anguis gr. An. fragilis , also anteroposteriorly elongated, whereas the perilymphatic foramen can be either moderately small or large. Like in scincids, the semicircular canals are narrow and poorly prominent.

BASIOCCIPITAL

The basioccipital ( Fig. 36) is unpaired, subhexagonal and roughly as long as wide. It has a dorsally concave body, with a central cranial depression and two moderately developed lateral wings. In dorsal view, it has a roughly straight or concave anterior margin. Posteriorly, it forms the medial portion of the occipital condyle. The ends of the lateral wings develop the sphenooccipital tubercles and constitute the ventral wall of the recessus scalae tympani. The crista tuberalis marks the posterior wall of the recessus. The basioccipital is smooth, both dorsally and ventrally. The bones that fuse with this bone are the sphenoid anteriorly, the prootics anterolaterally and the otooccipitals posterolaterally.