Green Basilisk Lizard © AMNH (click to enlarge) Veiled Chameleon © AMNH (click to enlarge) Red Spitting Cobra © AMNH (click to enlarge) Burmese Python © AMNH (click to enlarge)

What do iguanas, chameleons, monitor lizards, geckos, vipers, and cobras have in common? They're all squamates (skwah-mates). Squamata, which means "scaly" in Latin, is the name scientists use for the group that includes legged and legless lizards, including snakes.

Squamates are vertebrates, animals with a backbone. Unlike mammals and birds, which generate their own body heat, most squamates are ectothermic—they use external heat sources to maintain a relatively constant body temperature. All squamates have scales (though other kinds of animals do too) and they periodically shed their skin. Every squamate—each male and female—has paired, or two of the same, reproductive organs.

Fossil evidence shows that squamates existed at least 200 million years ago, when dinosaurs began to fl ourish. These early lizards were probably small, diurnal, ground-dwelling predators with spiky ridges down their backs. Over time, as squamates adapted to live in many different environments, they evolved extremely diverse characteristics. For example:

• Some squamates fly, some parachute, some walk upside down on ceilings, and some, like Green Basilisk Lizards, can even sprint across water.
  
• Some squamates, like Veiled Chameleons, have lightning-fast tongues that can be fired with pinpoint accuracy to grab prey.
  
• Some squamates have highly toxic venom that can subdue prey in seconds, and some, like Red Spitting Cobras, can spray venom into a predator's eyes.
  
• Some squamates may eat several times a day, while others, like Burmese Pythons, can get by with one large meal a year—when they can swallow whole an animal as large as a deer!