Lizard heads called the parietal eye, a basal ("primitive") feature also present in the tuatara. This "eye" has only a rudimentary retina and lens and cannot form images, but is sensitive to changes in light and dark and can detect movement. This helps them detect predators stalking it from above. Until 2006 it was thought that among lizards, only the Gila monster and the Mexican beaded lizard were venomous. However, several species of monitor lizards, including the Komodo dragon, produce powerful venom in their oral glands. Lace monitor venom, for instance, causes swift loss of consciousness and extensive bleeding through its
Yellow-throated plated lizard Yellow-throated plated lizard The yellow-throated plated lizard or plated lizard ("Gerrhosaurus flavigularis") is a species of lizard, which is about 45½ cm (18 inches) in total length (including tail) and lives in the grassland and scrub of Sudan, Ethiopia and along Eastern Africa down to South Africa. A ground-living and burrowing lizard, this species is usually greenish-grey or brownish, with a yellow (or sometimes red) throat and often a narrow stripe down each side. It is well armored, with hard body plates, and head shields fused to the skull. The tail is generally about two-thirds of the total length. Its