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
Viviparous lizard Viviparous lizard The viviparous lizard or common lizard, Zootoca vivipara (formerly "Lacerta vivipara"), is a Eurasian lizard. It lives farther north than any other species of non-marine reptile, and most populations are viviparous (giving birth to live young), rather than laying eggs as most other lizards do. It is the only species in the monotypic genus Zootoca. Both ""Zootoca"" and ""vivipara"" mean "live birth," in Greek and Latin respectively. It was called "Lacerta vivipara" until the genus "Lacerta" was split into nine genera in 2007 by , Arribas & Carranza. "Zootoca vivipara" can be seen in a variety of different