One of the most successful life form of the Earth is Reptile. Reptiles were the initial rulers of Earth. Though their throne was overthrown by catastrophic events few million years ago, yet reptiles are considered very powerful genre of animals till date.
The reptiles first appeared in Earth around 340 million years ago. They evolved from their ancestors amphibians, but they became stronger than the amphibians in two ways, a scaly outer skin that provided better protection and amniotic eggs that is independent of water. This helped them to increase the boundary from water to land. The reptiles flourished and diversified in wide variety types and soon became more dominant from the rest in the planet. They not only limit themselves to water and land, they started exploring the sky too. The reptiles started ruling the planet with power and intelligence. They evolved themselves to gigantic size known today as dinosaurs. They ruled land and sky for more than hundred million years until some exactly unknown catastrophic events. Their dynasty came to an end.
Millions of years ago, Earth was dominated by 20 groups of reptiles. But 16 of them lost the game of survival over the course of time. These 16 groups includes some magnificent animals that we can just imagine now.
There are only four groups of reptiles that are surviving today.
The largest surviving reptile group is the Squamata. The squamata includes lizards and snakes. There are around 6000 known living species of squamata.
The second group of today’s reptiles is the Crocodilians. It includes crocodiles, alligators and caimans. There are 23 species of Crocodiles are surviving. They are the largest of all present days reptiles. The Crocodilians first appeared about 84 million years ago and they are the closest living relatives of the birds.
The third groups is the Turtles. They are the oldest of the living reptiles. The turtles have changed little since they first appeared some 220 million years ago. They have a protective shell that encloses their body and provides protection and camouflage. There are 294 known species of turtles.
The fourth and the last surviving among the reptiles is called Tuataras. It is in fact the smallest group of reptiles. There is only kind of animal that represents this groups, named same as the group Tuatara. They are surviving on remote islands of New Zealand today. They are lizard-like in appearance but the fundamental difference is that their skull is not jointed. They first appeared around 220 million years ago and considered as living fossil by the researchers!