Because of this ridge, a few of these squamates are able to producing ventricular strain differentials that are equivalent to those seen in mammalian and avian hearts. Turtles have been traditionally believed to be surviving parareptiles, on the premise of their anapsid cranium construction, which was assumed to be primitive trait. The rationale for this classification has been disputed, with some arguing that turtles are diapsids that developed anapsid skulls to find a way to improve their armor. Later morphological phylogenetic research with this in mind positioned turtles firmly inside Diapsida. All molecular studies have strongly upheld the placement of turtles within diapsids, mostly as a sister group to extant archosaurs. Other examples include Westlothiana and Paleothyris, each of comparable build and presumably similar behavior.
Kansas State Reptile
