Scincidae

Scincidae View in CoL ( Figs 49I, J View Figure 49 , 50–R View Figure 50 , 51C View Figure 51 )

In scincids, all the bones (except the angular) fuse to form a compound bone. This ( Fig. 49I, J View Figure 49 ) is similar to the one of lacertids in morphology, even if it is more slender. The angular ridge starts closer to the posterior end of the bone compared to the latter group and the external opening of the posterior alveolar foramen is shifted dorsally compared to these, being visible in lateral view. The lateral surface is smooth, but its anterior-half is covered by the articulation surface with the dentary, which is more marked in larger species. The compound bone ( Figs 50K–R View Figure 50 , 51C View Figure 51 ) has a ventrally concave aspect in lateral view, because the retroarticular process bends in ventral direction. The concavity is size-linked, being less marked in smaller species (e.g. Ab. kitaibelii ; Fig. 50K, L View Figure 50 ). Nevertheless, the concavity is well distinct in the small Ophiomorus punctatissimus ( Fig. 50O, P View Figure 50 ). As in lacertids, the articular condyle is subquadrangular and has a medially developed and stocky tubercle on its anteromedial corner. The tubercle is poorly developed in Ab. kitaibelii and very well developed in Chalcides ocellatus ( Fig. 51C View Figure 51 ) and Ophiomorus punctatissimus . The retroarticular process is lobe-shaped in medial view, with a well-developed tympanic ridge running along its ventral margin. The only exceptions are Ab. kitaibelii and Ophiomorus punctatissimus , the process of which is subrectangular and has a less developed ridge ( Fig. 50K, L, O, P View Figure 50 ). The process is more anteroposteriorly elongated in Ab. kitaibelii , Chalcides chalcides and Chalcides striatus ( Fig. 50K, L View Figure 50 ) and more dorsoventrally expanded in Chalcides ocellatus , Ophiomorus punctatissimus and Tr. aurata ( Fig. 50M–R View Figure 50 ). There is no angular process. The lateral surface of the compound bone presents the articulation surfaces housing the narrow angular and the posterior end of the dentary, but it is otherwise smooth. The posterior surangular foramen is slightly shifted towards the dorsal margin of the bone. It is replaced by two smaller foramina in the left compound bone of a single specimen of Ophiomorus punctatissimus, MCZ 38517. Ophiomorus punctatissimus and Tr. aurata have a large anterior surangular foramen. The adductor fossa is narrow and anteroposteriorly elongated.