Trionyx messelianus is an extinct species of softshell turtle belonging to the family Trionychidae. These turtles lived in the Middle Eocene. Whether the various specimen found at the Messel Pit Fossil Site can be classified within the genus Trionyx is uncertain. Some authors believe that Trionyx messelianus from Messel should be considered synonym of Rafetoides austriacus (Peters, 1858), see Karl (1998).