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
Gran Canaria giant lizard Gran Canaria giant lizard The Gran Canaria giant lizard ("Gallotia stehlini") is a species of lizard in the family Lacertidae. The specific name, "stehlini", is in honor of Swiss paleontologist Hans Georg Stehlin, who collected the holotype. "Gallotia stehlini" grows to a total length (including tail) of up to . They are among one of the largest reptiles within the family lacertidae. The species comes in a variation of grays, browns and reddish hues. Unlike their female counterparts, males exhibit sizable jowls, robust heads and overall greater body mass. "Gallotia stehlini" is a true omnivore. The young often consuming various