Turtles are part of the most primitive group of reptiles that evolved into their current form more than 200 million years ago, having changed very little since then. They represent a transitional group between aquatic and terrestrial vertebrates that were the first to adapt to life on land, which is the reason why they acquired a few specific characteristics:
• They lay eggs protected by a membrane and a hard shell that retains moisture;
• Their skin is covered by scales and has few glands;
• They have well-developed lungs;
• They have locomotor limbs with claws on the fingers, which allow walking.