Trionychoidea

Trionychoidea is a superfamily of turtles comprising the softshell turtles and their closest relatives. These turtles are characterized by their flattened bodies, long necks, and leathery shells instead of the hard, bony carapace found in most other turtles. This unique shell structure allows for greater flexibility and is an adaptation for their predominantly aquatic lifestyle.

The superfamily is divided into two main families: Trionychidae and Carettochelyidae. Trionychidae, the softshell turtles, are a diverse group found throughout the world, inhabiting freshwater and brackish environments. They are known for their powerful bites and their ability to burrow into sand or mud. Species within this family include the Nile softshell turtle, the spiny softshell turtle, and the Asian giant softshell turtle.

Carettochelyidae contains only a single living species, the pig-nosed turtle of Australia and New Guinea. This species shares the leathery shell of softshell turtles but possesses paddle-like flippers more akin to sea turtles. It is found in freshwater rivers and estuaries. Fossil evidence suggests that trionychoid turtles have a long evolutionary history, with their origins dating back to the Cretaceous period. Their adaptations for aquatic life have allowed them to thrive in diverse aquatic ecosystems for millions of years.