Turtle shell

Scutes (left) and skeletal components (right) of a turtle's carapace. Scutes between the costal (= pleural) and marginals are called supramarginal.

Scutes (left) and skeletal components (right) of a turtle's plastron Pleurodires have an extra scute known as the intergular. It is mostly absent in cryptodires.

The turtle shell is a shield for the ventral and dorsal parts of turtles (the order Testudines), completely enclosing all the vital organs of the turtle and in some cases even the head.^[1] It is constructed of modified bony elements such as the ribs, parts of the pelvis and other bones found in most reptiles. The bone of the shell consists of both skeletal and dermal bone, showing that the complete enclosure of the shell likely evolved by including dermal armor into the rib cage.

The turtle's shell is an important study, not just because of the apparent protection it provides for the animal but also as an identification tool, in particular with fossils, as the shell is one of the likely parts of a turtle to survive fossilization. Hence understanding the shell structure in living species provides comparable material with fossils.

The shell of the hawksbill turtle, among other species, has been used as a material for a wide range of small decorative and practical items since antiquity, but is normally referred to as tortoiseshell.