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
Granite night lizard Granite night lizard The granite night lizard ("Xantusia henshawi" ) is a species of xantusiid lizard endemic to North America. The specific name, "henshawi", is in honor of American naturalist Henry Wetherbee Henshaw. "X. henshawi" is found in Mexico in the Mexican state of Baja California, and also in the United States in adjacent southern California. "X. henshawi" is flat-bodied with a broad, flat head and a soft skin. It has rounded, dark dorsal spots on a pale yellow or cream background. Its scales are granular on its dorsum, but large and squarish on the ventral surface. These lizards have