According to the online encyclopedia, Wikipedia, chameleons (family chamaeleonidae) are a distinctive and highly specialized clade of lizards. The chameleon has several very distinctive features not found in ordinary lizards.
One of their most unique features is that of the ability to change their colors. Melanophores are cells that contain the pigment “melanin” and have long tentacle like extensions that move up through the upper light reflecting layers. To change the color of the skin, the color cells alter in size, and by variation of the amounts of yellow, red, and dark brown, different colors are produced by a mixing effect. The light reflecting layers also help alter and vary the hue and tint. How the chameleon is able to know that he has matched perfectly the color and pattern of its environment without a mirror to check out his arrangement of pigments is remarkable. Some other type lizards have a limited ability to change colors but none as dramatically vivid and distinct as the chameleon.
Another distinctive feature is the feet. They are the only lizards with zygodactyle feet, or pincers. Zygodactyle feet have two toes pointing frontward and two pointing backward, which makes them extremely useful in climbing, grasping limbs, etc. Chameleons have five toes, three forward and two backward on the front feet and the opposite on the rear.
Another amazing feature are the independently moveable eyes, which allow chameleons the ability to survey the world with nearly 360-degree vision. These two eyes are mounted one on either side of the head and bulges out, but is covered almost completely other than the pupil by the eyelid. One may look up while the other looks down, or one frontward and the other backward.
Perhaps the most amazing of all is the structure and use of the tongue. There are two mechanisms operated by the powerful muscles that throw the tongue forward. At the back of the chameleon’s jaw lies a V-shaped bone with the point of the “V” facing backward. Attached to this bone, by a flexible joint, is the tongue bone over which the tongue fits like a glove on a finger. When the chameleon is about to shoot out its tongue, the V-bone is moved forward slightly to push the tip of the tongue out of the mouth. The circular muscles in the thick tip of the tongue then contract violently so that the tongue is forced out of the mouth. This violent, simultaneous, contraction of the circular muscle and relaxation of the longitudinal muscle allows the tongue to reach a length equal to the body length of the chameleon. In addition, the V-shaped bone is thrust farther out for added impetus to the tongue’s throw. The time required for this to occur is 1/16 of a second to extend the tongue, and 1/4 of a second to retract it. While sticky saliva on the end of the chameleon’s tongue causes its prey to become stuck, the tongue can also be used to grasp the insect.
One source proclaims that the tongue can reach twice the body length of the chameleon. (PBS.org)
Fossil records have not revealed any evidence of transitional forms for gradual evolution of this marvel of creation. It is obviously another example of God’s creative abilities in suiting creatures to their environment.