Trionychidae is a family of turtles, commonly known as softshell turtles or simply softshells. The family was described by Leopold Fitzinger in 1826. Softshells include some of the world's largest freshwater turtles, though many can adapt to living in highly brackish waters. Members of this family occur in Africa, Asia, and North America, with extinct species known from Australia. Most species have traditionally been included in the genus Trionyx, but the vast majority have since been moved to other genera. Among these are the North American Apalone softshells that were placed in Trionyx until 1987.
Archelon is an extinct marine turtle from the Late Cretaceous, and is the largest turtle ever to have been documented, with the biggest specimen measuring 4.6 m (15 ft) from head to tail and 2.2–3.2 t in body mass. It is known only from the Pierre Shale and has one species, A. ischyros. In the past, the genus also contained A. marshii and A. copei, though these have been reassigned to Protostega and Kansastega, respectively. The genus was named in 1895 by American paleontologist George Reber Wieland based on a skeleton from South Dakota, who placed it into the extinct family Protostegidae. The leatherback sea turtle was once thought to be its closest living relative, but now, Protostegidae is thought to be a completely separate lineage from any living sea turtle.
The Indian softshell turtle, or Ganges softshell turtle is a species of softshell turtle found in South Asia in rivers such as the Ganges, Indus and Mahanadi. This vulnerable turtle reaches a carapace length of up to 94 cm (37 in). It feeds mostly on fish, amphibians, carrion and other animal matter, but also takes aquatic plants. This turtle is listed in part II of Schedule I of the Wild Life (Protection) Act, 1972 and possession of this species is an offence.
Axestemys is an extinct genus of softshell turtle that lived from the Late Cretaceous to the Eocene in western North America and Europe.
Apalone is a genus of turtles in the family Trionychidae. The three species of Apalone are native to freshwater habitats in North America; they are the only living softshell turtles from the Americas.
Nilssonia is a genus of softshell turtles from rivers, streams, ponds, and lakes in South Asia and Burma. In many treatments, it is monotypic, with the single species Burmese peacock softshell. However, the supposed other genus of peacock softshells, Aspideretes, is more closely related to N. formosa than had been believed. They differ only in the neural plates between the first pleural scale pair of the bony carapace, which are fused into one in N. formosa and unfused in the others.
Desmatochelys is an extinct genus of sea turtles belonging to the family Protostegidae. This genus contains two known species, D. lowii and D. padillai. D. lowii was first discovered in 1895, followed by D. padillai in 2015. Having been estimated at over 120 million years old, D. padillai is currently the oldest known species of sea turtle.
The smooth softshell turtle is a species of North American softshell turtle in the family Trionychidae. This freshwater species is endemic to the United States, where it inhabits the Mississippi River system, along with other adjoining waterways that empty into the Gulf of Mexico.
Cearachelys is an extinct genus of pleurodiran turtle which existed some 110 million years ago. The genus is monotypic, with only type species Cearachelys placidoi known.
Thalassemys is a genus of extinct thalassochelydian turtle from the Late Jurassic of western and central Europe. While the genus was originally named by Rütimeyer in 1859 for a large carapace and other associated fragments from the late Kimmeridgian of the Reuchenette Formation of Switzerland, although the taxon was not validly named until 1873 when Rütimeyer designated the type species T. hugii. Rütimeyer also named T. gresslyi from the Reunchenette Formation in the same paper as T. hugii, but it cannot be differentiated from the type material of T. hugii and is therefore a junior synonym. A large assemblage of shell and postcranial material from the Reunchenette was named as a species of Eurysternum, E. ignoratum, by Bräm in 1965. While originally distinguished based on the presence of fontanelles on the plastron, the feature was later identified on T. hugii and E. ignoratum was designated a junior synonym. Additional material from the Kimmeridge Clay of the United Kingdom has also been referred to T. hugii.
Hutchemys is an extinct genus of softshell turtles from the late Cretaceous to the late Paleocene of New Mexico, Montana, Wyoming, Utah, and North Dakota, United States. It was first named by Walter G. Joyce, Ariel Revan, Tyler R. Lyson and Igor G. Danilov in 2009, and the type species is Hutchemys rememdium. H. rememdium is known from the holotype YPM PU 16795, which consists of a nearly complete postcranial skeleton, and from the referred specimen YPM PU 16781, found in the Ekalaka Member of the Fort Union Formation, Montana. Another referred specimen, YPM PU 14985, was found in the Cedar Point Quarry, Wyoming. The second species, H. arctochelys, is known from the holotype YPM PU 16319, a nearly complete carapace, and from the paratypes YPM PU 16320, YPM PU 16321, YPM PU 16322, YPM PU 16238. All specimens of H. arctochelys were recovered from the same quarry of the Tongue River Member, Fort Union Formation, near Burns Mine of Montana. A possible third species is represented by the unnamed specimen UCMP 130000 from the Paleocene Tullock Formation of Montana. Aspideretes? nassau (YPM PU 11566) from the Fort Union Formation, Duffy's Ranch of Sweet Grass County, Montana was also assigned to Hutchemys sp. A fourth species of Hutchemys, Hutchemys walkerorum, has been uncovered from the Hell Creek Formation of North Dakota. H. walkerorum is known from the holotype BDM 063, identified by the discovery and assembly of portions of its carapace. The fossil of H. walkerorum suggests that it was the only Hutchemys to live exclusively during the late Cretaceous era.
Cyclanorbinae, also known commonly as the flapshell turtles, is a subfamily of softshell turtles in the family Trionychidae. The subfamily is native to Africa and Asia.
The Trionychinae are a subfamily of turtles in the family Trionychidae.
Trionyx is a genus of softshell turtles belonging to the family Trionychidae. In the past many species in the family were classified in this genus, but today T. triunguis, the African or Nile softshell turtle, is the only extant softshell still classified as Trionyx. The other species still assigned to this genus are only known from fossils. T. triunguis is a relatively large, aquatic piscivore.
Gilmoremys is an extinct genus of softshell turtle which lived during the late Cretaceous of North Dakota, Montana and Wyoming, United States.
Khunnuchelys was a genus of trionychine turtle from the Late Cretaceous of Asia. Three species are known, K. erinhotensis, the type species, K. kizylkumensis, and K. lophorhothon. K. erinhotensis is known from the Iren Dabasu Formation in China from the late Turonian until the middle Campanian. K. kizylkumensis is known from the late Turonian Bissekty Formation of Uzbekistan. The third species, described in 2013 by Danilov et al., is known from the early to middle Campanian aged Bostobe Formation of Kazakhstan.
Chubutemys was an extinct genus of meiolaniform turtle. It lived during the Early Cretaceous of Argentina, around the Albian-Aptian border, within the Puesto La Paloma Member of the Cerro Barcino Formation. It is known from most of the skeleton and carapace, and part of the skull.
Basilemys is a large, terrestrial nanhsiungchelyid turtle from the Upper Cretaceous of North and Central America. 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. In an analysis made by Sukhanov et al. on a nansiunghelyid turtle from the Upper Cretaceous of Mongolia, it was demonstrated that Asian nanhsiungchelyids gave rise to the North American nanhsiungchelyids.
Drazinderetes is a large bodied genus of soft shell turtle from the Middle Eocene Drazinda Formation of Pakistan. Its presence in the shallow marine deposits of the Drazinda Formation suggests that Drazinderetes may have been a partially or fully marine animal. Indetermined trionychine remains from the same formation may suggest that Drazinderetes could have been among the largest known turtles, with one entoplastron indicating a potential length of 1.5 to 2.1 meters. Drazinderetes currently consists of only a single species: Drazinderetes tethyensis.
Rafetus bohemicus is an extinct species of softshell turtle from the Early Miocene (Burdigalian) of the Czech Republic. Specimens have been found at the northeastern margin of the Most Basin at a fossil site called Břešt’any. Fossil carapaces of "R. pontanus", a potential taxonomic synonym, have been found in slightly younger rocks in Lom and Louka u Litvínova.
