Agamidae

Agamidae is a diverse family of iguanian lizards. This group contains 582 different species organized into 64 genera.

Many people commonly refer to these lizards as dragons or dragon lizards. They are found throughout the Old World. This includes much of Africa, Asia, and Australia. They also live in small parts of southern Europe. However, they are absent from Madagascar and the New World. This distribution is the opposite of the Iguanidae family.

Most agamids possess distinct physical traits that set them apart from other lizards. They typically have strong, well-developed legs for movement. A key feature is their acrodont teeth. These teeth grow on the outer rim of the mouth. This is different from pleurodont teeth, which grow on the inner side of the jaw. This trait is rare among lizards. It is shared with chameleons and the tuatara. Most agamids are also heliothermic. This means they must bask in the sun to maintain high body temperatures.

Agamids live in many different environments. They can be found in hot deserts or lush tropical rainforests. One species, the mountain dragon, lives in much cooler regions. Many species are diurnal, meaning they are active during the day. They have good vision to help them hunt. Some live on the ground or on rocks. Others are arboreal, which means they live in trees. Members of the genus Draco are very unique. They have modified ribs that act like wings. These wings allow them to glide through forest habitats.

Scientists have worked to classify these lizards into six main subfamilies. The Agaminae live in Africa, Europe, and South Asia. The Amphibolurinae are found in Australia and New Guinea. Draconinae live in South and Southeast Asia. Hydrosaurinae inhabit Papua New Guinea, the Philippines, and Indonesia. The Leiolepidinae are located in Southeast Asia. Finally, the Uromastycinae live in Africa and South Asia. These subfamilies contain many different types of lizards. Some are popular pets, like the bearded dragon or Chinese water dragon.

Reproduction in agamids often involves laying eggs, a process called being oviparous. Most species lay clutches of four to 10 eggs. These eggs are usually placed in damp soil or rotting logs. This helps them stay moist during incubation. The incubation period typically lasts between 6 and 8 weeks. In the Leiolepidinae subfamily, lizards use a specific burrowing system. They deposit eggs in moist soil during late spring or early summer. These burrows also help them regulate temperature or hide from predators.

Research into Agamidae has grown over many decades. The first complete assessment was conducted by Moody in 1980. Frost and Etheridge provided a larger assessment in 1989. Later, scientists like Macey and Honda studied mitochondrial DNA in 2000. Joger also performed studies by sampling across the family in 1991. The evolutionary history of these lizards is very long. The oldest known unambiguous agamid is Protodraco. It lived about 99 million years ago during the mid-Cretaceous period. It was found in Burmese amber in Myanmar.

A lizard's body temperature directly affects how it reacts to danger. There is a positive correlation between temperature and their flight response. When their bodies are warm, they tend to run away quickly. This is a flight response to escape predators. When their temperatures are lower, they show a fight response. This means they are more likely to be aggressive and attack. Some species, like the frilled-neck lizard, use physical features for defense. They display a large frill when threatened. Males also use bright colors and frills during the mating season to signal others.