Chalcides ocellatus and Chalcides guentheri (Merram 1820) both extant skinks, represent variation found within a genus. The more primitive C. ocellatus had a shorter skull, larger upper temporal fenestra and larger limbs. The more derived C. guentheri had a longer skull, smaller upper temporal fenestra and smaller limbs coupled with a longer torso. Derived from a sister to Gobiderma, Chalcides was a phylogenetic predecessor to Gymnophthalmus and burrowing skinks like Sirenoscincus.
Distinct from Gobiderma, the skull of C. ocellatus had near contact between the squamosal and the postorbital. The postfrontal remained unfused. The upper temporal fenestra were larger due to a pinched parietal. The basisphenoid and basiocciput were smaller. The vomers were larger and the pterygoids more robust.
Distinct from C. ocellatus, the posterior skull of C. guentheri was elongated. The postfrontal descended to the jugal. The postorbital was reduced to a sliver. The parietal was wider and the upper temporal fenestrae were mere slits. The basiocciput was greatly expanded. The vomers were laterally expanded. |
