Uetz reported that 51 percent of known reptile species belong to one of three families: colubrid snakes (1,850 species), skinks (1,200), and geckos (1,000).
New reptile species continue to be described at the rate of about 60 species per year (Uetz 2000).
Westlothiana, also suggested as the oldest reptile, is for the moment considered to be related more to amphibians than to amniotes.
Hylonomus, the oldest-known reptile, was about 8 to 12 inches (20 to 30 cm) long.
Lung ventilation is accomplished differently in each main reptile group.
Reptiles include alligators, crocodiles, turtles, and snakes. Amphibians include salamanders, toads, and frogs. One difference between the two is the structure of their outer skin. Reptiles are covered with scales, shields, or plates, and their toes have claws.
Most reptiles lay eggs and their skin is covered with hard, dry scales. Animals that are cold-blooded don't automatically maintain a constant body temperature. They have to lay out in the sun to keep their body heat up.
Reptiles have dry, scaly skin. They move by either creeping on short legs or crawling on their bellies. Most reproduce by laying eggs.A cold-blooded, air-breathing animal that has a backbone. Reptiles have dry, scaly skin.
The first and foremost characteristic of the reptiles is that are cold blooded. They are able to regulate their inner body temperature to the temperature of the environment. They have scaly skins but absence of hair or fur. The scales of the reptiles develop as a surface cells filled with Keratin.
Reptile Reproduction. Most reptiles reproduce sexually and have internal fertilization. Males have one or two penises that pass sperm from their cloaca to the cloaca of a female. Fertilization occurs within the cloaca, and fertilized eggs leave the female's body through the opening in the cloaca.Feb 24, 2012
So birds aren't just closely related to dinosaurs, they really are dinosaurs! This is what most people mean when they say that birds are reptiles, although technically according to the phylogenetic system mammals are also reptiles. You may wonder why biologists have two systems of classification.
The largest carnivore that ever walked the planet – Tyrannosaurus rex – is more closely related to the modern chicken than it is to living reptiles such as the alligator or crocodile, a study of the dinosaur's fossilised protein has found.Apr 24, 2008
Snakes, lizards, turtles, crocodilians, and birds are reptiles. Like all vertebrates, reptiles have bony skeletons that support their bodies. ... Some types of reptiles (such as sea turtles and penguins) are adapted to living in water, but even these species come onto land to lay their eggs.