WTrionychia is a superfamily of turtles which encompasses the species that are commonly referred to as softshelled turtles as well as some others. The group contains two families, Carettochelyidae, which has only one living species, the pig-nosed turtle native to New Guinea and Northern Australia, and Trionychidae, the softshelled turtles, containing numerous species native to Asia, North America and Africa. The oldest known stem-tryonychian is Sinaspideretes from the Late Jurassic of China.
WThe Adocidae are an extinct family of aquatic and omnivorous turtles. They are freshwater cryptodiran turtles and are mainly known from Cretaceous and Paleogene Asia and North America.
WAdocus is an extinct genus of aquatic turtles belonging to the family Adocidae. Adocus was once considered a genus belonging to the family Dermatemyidae.
WAdocus beatus is an extinct species of aquatic turtles belonging to the family Adocidae.
WBasilemys is a large, terrestrial trionychoid turtle from the Upper Cretaceous. In Greek, the word "Basil" means royal or kingly and the word "Emys" means turtle. Therefore, Basilemys means King Turtle. Basilemys has been found in rocks dating to the Campanian and Maastrichtian subdivisions of the Late Cretaceous and is considered to be the largest terrestrial turtle of its time. Basilemys has solely been found in North America. The family Nanhsiungchelyidae, which is the family Basilemys belongs to, made its first appearance in the Lower Cretaceous, in what we now call Asia. Because of Basilemys, we know that this family appeared in North America in the Upper Cretaceous. It is possible that Basilemys and other nanhsiungchelyids are immigrants from Asia. They might have arrived in North America by passing through what we now call the Bering Strait somewhere during the Cretaceous. In an analysis made by Sukhanov et al. on a new Nansiunghelyid turtle from the Upper Cretaceous of Mongolia, it was demonstrated that Asian nanhsiungchelyids gave rise to the North American nanhsiungchelyids. Basilemys shares some traits with another member of nanhsiungchelyidae, Zangerlia, which is similar to Basilemys in, for example, skull proportions. However, Basilemys has a more complex triturating surface that includes well-defined pockets on the dentary, and it also has tooth-like projections on the triturating surface of the maxilla.
WCarettochelyidae is a family of cryptodiran turtles belonging to the Trionychia. It contains only a single living species, the pig-nosed turtle native to New Guinea and Northern Australia. Stem-group carettochelyids are known from the Cretaceous of Asia, with the family being widely distributed across North America, Europe and Asia during the Paleogene.
WNanhsiungchelyidae is an extinct family of land turtles known from Cretaceous deposits in Asia and North America. Nanhsiungchelyids were more terrestrial than many of their contemporaries, and may have gone extinct at the end of the Cretaceous as a result.