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 large eyes with vertical pupils, and they lack eyelids. Granite night lizards are often found on rocky slopes with large exfoliating boulders and abundant crevices, but are occasionally found in coastal sage scrub and chaparral without boulders. They are active in crevices during the day, but move on the surface at night. 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