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
Aran rock lizard Aran rock lizard The Aran rock lizard ("Iberolacerta aranica") is a species of lizard in the family Lacertidae. "I. aranica" is found in a small area of the central Pyrenees on the Spanish-French border. It lives only in Mauberme massif, including its foothills between the Val d'Aran in Spain and the Ariège in France. The natural habitats of "I. aranica" are temperate grassland, rocky areas, and pastureland. "I. aranica" is threatened by habitat loss. The Aran rock lizard is a medium-sized lizard. Males can reach a total length (including tail) of up to , females up to . The back