Anguidae

Anguidae View in CoL View at ENA ( Figs 34 View Figure 34 , 36G View Figure 36 )

The basioccipital is slightly longer than it is wide in Anguis gr. An. fragilis ( Figs 34E View Figure 34 , 36G View Figure 36 ), but in Pseudopus apodus length and width of this bone are roughly similar ( Fig. 34J View Figure 34 ). Posteriorly, the basioccipital of anguids composes more than one-third of the occipital condyle. Sphenooccipital tubercles are moderately or well developed in Anguis gr. An. fragilis ( Fig. 34B, C View Figure 34 ), and always well developed in Pseudopus apodus ( Fig. 34F–H View Figure 34 ). They are subtriangular (but with a rather rounded ventral end) in lateral view and almost entirely excluded from the recessus scalae tympani by two expansions of the otooccipital. The degree of development of the tubercles increases with growth, but they are, as a rule, larger in Pseudopus apodus than in Anguis gr. An. fragilis .

SPHENOID

The complete fusion of parasphenoid and basisphenoid results in an unpaired sphenoid ( Fig. 37 View Figure 37 ). This bone has a roughly quadrangular body, from which two basipterygoid processes develop anterolaterally from the anterolateral corners.Two posterolaterally directed cristae ventrolaterales [parasphenoid wings in Daza et al. (2008)] can be also present at the posterolateral corners. On the dorsal surface of the body of the bone, there are two cylindrical trabeculae cranii, the sella turcica (including the hypophysial fossa) and the transverse crista sellaris. The trabeculae, located between the basipterygoid processes, are continued posteriorly by two low cristae trabeculares that border the sella turcica laterally. A parasphenoid rostrum [cultriform process in Daza et al. (2008)] can be present between the trabeculae, on the anterior margin of the bone. The crista sellaris composes the posterior margin of the sella turcica and contacts the prootics laterally, with the alar processes. The crista can develop anterodorsally to form a dorsum sellae that covers the sella turcica. Moreover, it is pierced anteroposteriorly by two abducens foramina. The dorsal surface of the posterior portion of the sphenoid, located posteriorly to the crista sellaris, is smooth. Ventrally, the sphenoid can have a sunken area in the middle.The Vidian canals open anteriorly medial to the base of the basipterygoid process, medially in the sella turcica (with the internal carotid foramina) and posterolaterally towards the contact with the prootics. Both sides of the sphenoid display the recessus vena jugularis extending in a posterodorsal direction, starting from the latter openings. The recessus continues on the prootics. The sphenoid contacts the basioccipital posteriorly and the prootics posterolaterally.