Zonuridae and Anguidae assume a central position, with Agamidae and Iguanidae as two parallel families (not very different from each other) of highest development, one in the Old World, the other in America.
Xenosaurus seems to be an offshoot intermediate between the Iguanidae and the Anguidae; a degraded form of latter is perhaps Aniella of California, whilst Heloderma and Lanthanotus are also specialized and isolated offshoots.
A third group comprises the cosmopolitan Scincidae, the African and Malagasy Gerrhosauridae which in various features remind us of the Anguidae, and the African and Eurasian Lacertidae which are the highest members of this group. Anelytropidae and perhaps also Dibamidae may be degraded Scincoids.
Tongue resembling that of the Anguidae.
The temporal region is covered over, as in the Lacertidae and Anguidae, with strongly developed dermal ossifications.