Caméléon

Chameleons may have evolved from lizards, with the oldest known fossils dating from the Cretaceous. Some authors suggest that the genus Mimeosaurus (Gilmore, 1928) is the direct ancestor of modern chameleons (Romer, 1966). Definitive ancient chameleon fossils are quite rare. The oldest known, Chamaeleo caroliquarti, was discovered in Central Europe and dates to 26 million years ago. In 1999, a fossil dating to 99 million years ago, with a long tongue and an entoglossal element (an elongated part of the hyoid bone that allows chameleons to project their tongue), was thought to be an ancestral chameleon (suggesting an Asian origin for chameleons); however, its 2020 description showed it was actually an amphibian with no direct phylogenetic relationship. Madagascar is often considered the cradle of chameleons, as it is home to the majority of existing species and the greatest variety of forms. However, this idea is now contested. Many authors believe chameleons originated from East Africa, based on the fact that numerous different forms are found there and fossils exist (Hillenius, 1959). To support this theory, genetic research (Matthey, 1957; Matthey & Van Brink, 1960) showed that chameleons had two types of chromosomes, one "continental" and the other "island." Chameleons from Madagascar and nearby islands have both types, while others have only the continental type. This suggests later diversification for Malagasy species. In the past, chameleons had a much wider distribution than today. They were found in Africa but also in China (Anquingosaurus brevicephalis Hou, 1976) and Central Europe (Chamaeleo bavaricus Scheich, 1983 and C. caroliquari Moddy & Rocek, 1980). They retreated southward during the Quaternary, as temperatures dropped in the Northern Hemisphere, and are now found only in southern Italy, southern Spain, Portugal and Greece (Chamaeleo chamaeleon) in the European part. Arabia was populated by three series of successive migrations, corresponding to distinct species or subspecies (Chamaeleo arabicus, C. calyptratus and C. chamaeleon orientalis) (Arnold, 1980, Hillenius & Gasperetti, 1984, Necas, 1995). Today, some species have been introduced by humans as a result of animals being released into the wild. This is particularly the case in Hawaii (Chamaeleo jacksonii originally from Kenya), and a few populations in California, Alabama and Australia. This is also the case with Furcifer pardalis introduced to Réunion where it has adapted very well and enjoys protected species status.

This chameleon is considered "solitary" because it tolerates having another chameleon in front of it very poorly. When threatened, the chameleon may change its behavior. It puffs out its sides and changes color with quite vivid colors. It opens its mouth and hisses until one of the two is dominated and leaves.

Males can reach 50 to 60 cm in length and are green in color with yellow and orange stripes, unlike females which are uniformly blue or green. They have a distinctive imposing helmet on their head. The helmeted chameleon inhabits humid areas with a large temperature range (25-30°C during the day and 20°C at night). It can be observed in cultivated areas or at the tops of trees. Native to the forests of the Arabian peninsula (Yemen and Saudi Arabia). Its main feature is the presence of a "helmet" on the skull, twice as large in males as in females, and can reach 8 cm. The basic coloration, green and yellow, can change to an impressive range of different colors. Contrary to popular belief, these changes do not occur to blend in with the environment, but to follow internal factors (emotional state, health status) or external ones (for example, a darker color allows it to better absorb heat from the sun). Like all chameleons, it is primarily insectivorous and hunts using its tongue which reaches the same length as its body. It can project it to catch its prey thanks to its sticky tip. As an adult, it becomes omnivorous and then also eats vegetation. The Calyptratus chameleon, also nicknamed the Yemeni helmeted chameleon, because of the country it comes from and its helmet which is very imposing especially in males. It can also be found in Saudi Arabia and the United States where it has been successfully introduced by humans. In captivity, this is a chameleon that can be recommended to beginners. Its maintenance is easy as long as the proper environmental parameters are strictly respected. A mesh terrarium is essential to ensure good air circulation, with many branches. The temperatures at the hot spot range from 30 to 40°C depending on the age of the animal, with a cool zone of 24 to 26°C. A UVB light source is also essential. Humidity should not be too high, but daily misting allows the chameleon to drink. Beware, males are very territorial and cannot be kept together. Animals can be sexed young: males have spurs on their hind legs that females do not have.

All chameleons are insectivores. They catch most of the insects that come within their reach. Some species—generally the larger ones—also consume small birds and small lizards or geckos. Captive chameleons are fed insects such as crickets, cockroaches and woodlice. Chameleons also eat vegetables, although some plants are toxic to them (such as ivy).