Cotylosaurs

 

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.