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
Cuban night lizard Cuban night lizard The Cuban night lizard ("Cricosaura typica") is a night lizard (family Xantusiidae, subfamily Cricosaurinae) endemic to southern Cuba. It is the only member of the genus "Cricosaura", one of three in the night lizard family. "Cricosaura" is derived from the Greek words "krikos" and "saura" meaning "ring lizard", perhaps in reference to the rings of caudal scales. The name ""typica"", from the Greek word "typikos", means "typical". The Cuban night lizard differs from the other night lizards in possessing two frontonasal scales, one frontal scale, no parietal scale, and a fourth finger with four phalanges. With a