Turtle | My Dinosaurs

turtle

Turtles are reptiles of the orderTestudines (or Chelonii) characterised by a special bony orcartilaginous shell developed from theirribs and acting as a shield. “Turtle” may refer to the order as a whole (American English) or to fresh-water and sea-dwelling testudines (British English).

The order Testudines includes both extant (living) and extinct species. The earliest known members of this group date from157 million years ago, making turtles one of the oldest reptile groups and a more ancient group than snakes orcrocodilians. Of the 327 known speciesalive today, some are highlyendangered.

Turtles are ectotherms—animals commonly called cold-blooded—meaning that their internal temperature varies according to the ambient environment. However, because of their high metabolic rate, leatherback sea turtles have a body temperature that is noticeably higher than that of the surrounding water.

Turtles are classified as amniotes, along with other reptiles, birds, and mammals. Like other amniotes, turtles breathe air and do not lay eggs underwater, although many species live in or around water.