Lizards survive in the desert because they have many adaptations as reptiles that help them to avoid the extreme heat during the day, the extreme cold during the night and keep moist despite the dry weather. The first of all of these adaptations was the adaptation that took the lizard from a swimming lung fish in the Paleozoic era to an earth-crawling lizard today.
From there, the lizard developed adaptions that allowed it to survive in its environment starting with thermoregulation. Thermoregulation is necessary to withstand both the extreme heat and the extreme cold of the desert. In order for thermoregulation to work, the lizard tries to keep itself in the shade during the heat and out of the shade during the cold. It also keeps itself close to hot surfaces when it is cold. The color of many lizards can also change allowing them to either absorb heat quickly or more slowly.
When there are a lot of changes happening in the desert, the lizard hides itself in burrows. It rarely digs these burrows, but it climbs into the burrows that other animals have created. By burrowing so low into the ground, the lizard is able to slow down its metabolic processes. This means that the lizard will not need to eat as much food and can stay under the ground longer making it easier to survive.