What is "testudinata"

Testudinata \Tes*tu`di*na"ta\, n. pl. [Nl. See Testudo.] (Zo["o]l.) An order of reptiles which includes the turtles and tortoises. The body is covered by a shell consisting of an upper or dorsal shell, called the carapace, and a lower or ventral shell, called the plastron, each of which consists of several plates.

Testudinata is the group of all tetrapods with a true turtle shell. It includes both modern turtles (Testudines) and many of their extinct, shelled relatives (stem-turtles). Though it was first coined as the group containing turtles by Klein in 1760, it was first defined in the modern sense by Joyce and colleagues in 2004. Testudinata does not include the primitive stem-turtle Odontochelys, which only had the bottom half of a shell.