Types of Turtles

There are two types of turtles in this world, marine and freshwater notwithstanding: pleurodira and cryptodira. Pleurodiran turtles retract their heads into their shells by bending their necks in the axial lpane whereas cryptodiran turtles lower their necks and retract their heads into their shells. The majority of living turtles are cryptodiran turtles, but there are notable groups of pleurodirans as well. Stupendemys is one such notable member of the pleurodira. the anatomy of this system of hiding its head has been described in many papers, notably in Scheyer and Sanchez-Villagra 2007 and the slightly older de Broin, et al. 1993. The initial description of the turtle is not online; however, the description of the second species named, Stupendemys souzai, is available online. This is a good reference for not only the anatomy of the genus, but also general turtle anatomy, as modern knowledge of turtles is used to more accurately describe the fossil by the authors Bocquentin and Melo.