Amazing Animal Pictures BiographyChameleons (Chamaeleonidae) form a group of lizards that includes about 160 species. Chameleons are most noted for their unique feet, stereoscopic eyes and lighting-fast tongues. Chameleons are arboreal creatures and consequently their feet are specially adapted for grasping branches and twigs. They have five toes on each foot which are fused into two bundles (one of two toes, the other of three toes). This foot structure, referred to as zygodactyly, offers chameleons a strong grip.
Chameleons have cryptic coloration and are capable of changing their color and pattern to blend with their surroundings. They accomplish this color change by contracting or expanding cells in their skin that contain pigments. Their body shape is arched and leaf-like in shape.
Chameleons are carnivores. They feed on insects and spiders. Larger species of chameleons also feed on small vertebrates such as mammals and birds. To catch prey, chameleons launch their long tongue from their mouth using specialized muscles. The tip of the tongue is equipped with a suction-cup-like structure which is coated in mucus.
Chameleons are lizards, a group of reptiles that (in addition to chameleons) includes iguanas, chisel-teeth lizards, geckos, night lizards, blind lizards, skinks, anguids, beaded lizards and many others. There are approximately 160 species of chameleons that are divided into about 9 subgroups (genera).
The oldest known chameleon from the fossil record is Chamaeleo caroliquarti a species that lived about 26 million years ago
Snakes (Serpentes) are a diverse group of squamates that consists of about 2900 species. Snakes have no limbs but their legless nature doesn't stop them from being among the world's most formidable reptilian predators. Limbs are not the only structure snakes lack, they also have no eyelids, no external ears, and most species have only one functional lung. Snakes have long, slender bodies and a long tail. Snakes range in size from the tiny Barbados Threadsnake—which measures a mere 10 cm in length—to the gargantuan anacondas, pythons and boas—which can grow to lengths in excess of 30 feet.
The internal organs of most snakes have been modified over the course of their evolution to accommodate their slender form. As noted above, most snakes only have one functional lung (the right lung) instead of two—this saves space within their slender body. Their stomachs are elongated, their intestines are less coiled than those of other squamates and their kidneys are staggered and elongated.
Like all reptiles, snakes' skin is covered in scales. The color and arrangement of these scales is often helpful in identifying the various snake species. Snakes have many vertebrae in their backbones—in some species, their vertebrae number in the hundreds. The vertebrae of a snake's backbone are loosely jointed together to enable them great flexibility. This enables them to move with great agility and to wind their bodies into compact coils.
Snakes are squamates, a group of reptiles that also includes lizards and worm-lizards. Snakes comprise about 18 subgroups, some of which include boas, colubrids, pythons, vipers, blind snakes, mole vipers and sunbeam snakes.
Snakes are among the most recently evolved of the main reptile lineages alive today. Their evolutionary history remains somewhat murky though—their delicate skeletons do not preserve well and as a result few fossil remains of ancient snakes have been recovered. The earliest known snake is Lapparentophis defrenni which is estimated to have lived about 130 million years ago, during the early Cretaceous.
Crocodilians (Crocodilia) are a group of reptiles that includes crocodiles, alligators, caimans and the gharial. Crocodilians are semi-aquatic predators that have changed little since the time of the dinosaurs. All species of crocodilians have similar body structures—elongated snout, powerful jaws, muscular tail, large protective scales, streamlined body, and eyes and nostrils that are positioned on top of the head.
Crocodilians have several adaptations that make them well-suited for an aquatic lifestyle. They have an extra transparent eyelid on each eye that can be closed to protect their eye when underwater. They also have a flap of skin at the back of their throat that prevents water from seeping in when they attack prey underwater. They can also close their nostrils and ears in a similar manner to prevent the unwanted influx of water.
Crocodilian males are territorial animals that protect their home range from other male intruders. Males share their territory with several females with whom they mate. Females lay their eggs on land, near water in a nest built out of vegetation and mud or in a hollow in the ground. Females care for the young after they hatch, providing them with protection until they grow large enough to defend themselves. In many species of crocodilians, the female carries her tiny offspring in her mouth.
Crocodilians are carnivores. They feed on live animals such as birds, small mammals and fish. They also feed on carrion. Crocodilians use several methods of attack when pursuing live prey. One approach is that of ambush—the crocodilian lies motionless beneath the water's surface with only their nostrils above the water line. This enables them to remain concealed while they watch for prey that approaches the water's edge. The crocodilian then lunges out of the water, taking their prey by surprise and dragging it from the shoreline into deep water for the kill. Other hunting methods include catching fish using a quick side-snap of the head or catching waterfowl by drifting towards it slowly and then lunging for it when at close range.
Crocodilians first appeared about 84 million years ago during the late Cretaceous.
Animals > Chordates > Vertebrates > Reptiles > Crocodilians
Crocodilians are diapsids, a group of reptiles that possess two holes (or temporal fenestra) on each side of their skull. Other diapsids include dinosaurs, pterosaurs, and the squamates, a group that encompasses modern lizards, snakes and worm lizards. Crocodilians are subdivided into three groups: gharials, crocodiles and alligators.
More About Reptiles
Squamates (Squamata) are the most diverse of all the reptile groups, with approximately 7400 living species. Squamates include lizards, snakes and worm-lizards.
Two characteristics that unite the squamates. The first is that they shed their skin periodically. Some squamates, such as snakes, shed their skin in one piece. Other squamates, such as many lizards, shed their skin in patches. In contrast, non-squamate reptiles regenerate their scales by other means—for example crocodiles shed a single scale at a time while turtles do not shed the scales that cover their carapace and instead add new layers from beneath.
The second characteristic shared by squamates is their uniquely jointed skulls and jaws, which are both strong and flexible. The extraordinary jaw mobility of squamates enables them to open their mouths very wide and in doing so, consume large prey. Additionally, the strength of their skull and jaws provides squamates with a powerful bite grip.
Squamates first appeared in the fossil record during the mid Jurassic and probably existed before that time. The fossil record for squamates is rather sparse. Modern squamates arose about 160 million years ago, during the late Jurassic. The earliest lizard fossils are between 185 and 165 million years old.
The closest living relatives of the squamates are the tuataras, followed by the crocodiles and birds. Of all living reptiles, turtles are the most distant relatives of the squamates. Like crocodilians, squamates are diapsids, a group of reptiles that possess two holes (or temporal fenestra) on each side of their skull.
Animals > Chordates > Reptiles > Squamates
Squamates are divided into three subgroups, the lizards, snakes and worm-lizards.