Cotylosaurs were organisms that
lived during the Permian period, and are thought to be the ancestors of
marine reptiles, such as Icthyosaurs and turtles. There is some debate
related to whether or not Cotylosaurs were reptiles, and whether or not
they are related to marine reptiles. The most accepted theory is that Cotylosaurs
were amphibians, although many Cotylosaurs possessed reptilian features.