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
Northern caiman lizard Northern caiman lizard The northern caiman lizard, "Dracaena guianensis", is a species of lizard found in northern South America. The caiman lizard is built similarly to its cousin the tegu, with a large heavy set body and short but powerful limbs. Its head is bulky and often a red or orange color. Their jaws are heavily muscular to help aid in eating its normal prey of snails, crawfish and fresh water clams. It also has a few adaptations that help it in its watery habitat. It has a long and flattened tail, similar to its namesake, the caiman. The long