Sea turtles appeared on Earth about 150 million years ago. They had their origin on land, having evolved and differentiated from other reptiles during their adventure into the sea. Most turtles that existed in that era are now extinct. Those that survived have colonized all the oceans and gave rise to the various species, which roam the oceans around the world, and use the beaches in subtropical, tropical and temperate climates to reproduce.
Turtles, or chelonians, are reptiles of the order Testudinata, which are characterized by having a body protected by a bony shell. While some remained in terrestrial environments, others sought freshwater or ventured out to sea, evolving and differentiating themselves from other reptiles.