Chameleons have been around for tens of millions of years (~90 million). The 300+ species of the family chamaeleonidae (ie. chameleons) are highly specialized lizards that occupy many different environments. From deserts, to tropical rainforests, to snow-capped peaks, chameleons have used their unique adaptations to forge homes from India to Cameroon, and from South Africa to Spain.
These unique adaptations include independently moving eyes that provide nearly 360 degree vision; a projectile tongue capable of reaching at least their own body length; fused sets of toes providing the reptile version of opposable thumbs, and their peculiar proclivity for pigment permutation--ie. their curious convention of chromataphoric conversion.
While all chameleons share characteristics unique to the family chamaeleonidae, they are by no means a homogenous group. Species such as Calumma parsonii can tip the scales at a kilogram, while some members of the genus Brookesia and Rhampholeon are among the smallest vertebrates on the planet. Similarly, the Namaqua chameleon (Chamaeleo namaquensis) plods the deserts of Namibia in search of its favoured prey, while the helmeted chameleon (Trioceros hoehnelli), whose range can exceed 3000m in elevation, sees frost during the cold season.
With their repertoire of incredible adaptations and the range of environments in which they have adapted to live, it is no wonder that chameleons are the best reptile!