There are more than 6,500 types of reptiles today. Many modern reptiles that can be traced back to ancient animals that are now extinct.
Reptiles’ ancestors lived in prehistoric times. Prehistoric means “before people could write.” Protosuhchus, a species of reptile that lived 190 million years ago, was one of the first reptiles and was related to the crocodile. Protosuchus had long legs and was three feet long.
Today there are four main groups of reptiles. The largest living reptile, the crocodile, is part of a group called crocodilians. Crocodilians have a skeleton and a backbone. They also have tough, thick, horned plates that cover their skin. They live near water and are strong swimmers. Other reptiles in the crocodilian group include alligators, caimans, and gharials.
While all reptiles have a lot of things in common, their size and shape can vary greatly. Some reptiles, including turtles, terrapins, and tortoises have shells to protect their soft bodies. They are part of the “reptiles with shells” group.
Another type of reptile is the tuatara. Tuataras belong to the smallest group of reptiles and can be found on a few small islands on the coasts of New Zealand.
The largest group of reptiles is lizards and snakes. More than 3,00 species exist around the globe. Reptiles come in all sorts of different sizes and shapes. You can see many of them today at your local zoo.
[Sources: Kingfisher Young Knowledge Reptiles; 100 Things You Should Know About Prehistoric Life]