Podocnemididae is a family of pleurodire (side-necked) turtles, once widely distributed. Most of its 20 genera and 30 species are now extinct. Seven of its eight surviving species are native to South America: the genus Peltocephalus, with only one species ; and the genus Podocnemis, with six living species of South American side-necked river turtles. There is also one genus native to Madagascar: Erymnochelys, the Madagascan big-headed turtle, whose single species E. madagascariensis.
The Pleurodira are one of the two living suborders of turtles, the other being the Cryptodira. The division between these two suborders represents a very deep evolutionary divide between two very different types of turtles. The physical differences between them, although anatomical and largely internal, are nonetheless significant, and the zoogeographic implications of them are substantial. The Pleurodira are known more commonly as the side-necked turtles and the name Pleurodira quite literally translates to side neck, whereas the Cryptodira are known as hidden-necked turtles. The Pleurodira turtles are currently restricted to freshwater habitats in the Southern Hemisphere, largely to Australia, South America, and Africa. Within the Pleurodira, three living families are represented: Chelidae, also known as the Austro-South American side-necked turtles, the Pelomedusidae, also known as the African mud terrapins, and the Podocnemididae, also known as the American side-neck river turtles. However, they were cosmopolitan clade during the Cretaceous and most of the Cenozoic, and even occurred in marine environments around the world.
Bothremydidae is an extinct family of side-necked turtles (Pleurodira) known from the Cretaceous and Cenozoic. They are closely related to Podocnemididae, and are amongst the most widely distributed pleurodire groups, with their fossils having been found in Africa, India, the Middle East, Europe, North America and South America. Bothremydids were aquatic turtles with a high morphological diversity, indicative of generalist, molluscivorous, piscivorous and possibly herbivorous grazing diets, with some probably capable of suction feeding. Unlike modern pleurodires, which are exclusively freshwater, bothremydids inhabited freshwater, marine and coastal environments. Their marine habits allowed bothremydids to disperse across oceanic barriers into Europe and North America during the early Late Cretaceous (Cenomanian). The youngest records of the group are indeterminate remains from Saudi Arabia and Oman, dating to the Miocene.
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.
Kinkonychelys is an extinct genus of side-necked turtle which existed in Madagascar during the Late Cretaceous period. It contains the single species Kinkonychelys rogersi, named in honor of its discoverer, Raymond R. Rogers. The genus and species are based on UA 9748, a nearly complete skull, which represents the first turtle skull described from the pre-Holocene era in Madagascar. A number of isolated skull and jaw bones have also been assigned to K. rogersi. These specimens were found in rocks of the Maastrichtian-age Maevarano Formation in the Mahajanga Basin of northwestern Madagascar. Another specimen, FMNH PR 2446, is speculated to represent another species, currently known as Kinkonychelys sp., but consensus on its distinction from K. rogersi remains unclear.
Sankuchemys is an extinct genus of side-necked turtle whose fossils had been found in the Intertrappean Formation of India during the late Cretaceous period. It was first named by Eugene S. Gaffney, Ashok Sahni, Herman Schleich, Swarn Deep Singh, and Rahul Srivastava in 2003, and contains the species Sankuchemys sethnai.
Kurmademys is an extinct genus of side-necked turtle which existed in India during the late Cretaceous period. It was first named in 2001, by Eugene S. Gaffney, Sankar Chatterjee, and Dhiraj K. Rudra, and contains the species Kurmademys kallamedensis. The species name is derived from the Kallamedu Formation of southern India, where the type specimen of the genus was discovered. It was assigned to the family Bothremydidae.
Sokatra is an extinct genus of pleurodiran turtle, known from the Cretaceous (Maastrichtian) Maevarano Formation of Madagascar. It belongs to the family Sahonachelyidae.
Foxemys is an extinct genus of bothremydid turtle that was discovered at Fox Amphoux, France and also Hungary and Spain. Its skull and shell structure is similar to Polysternon. Two species are in the genus: F. mechinorum and F. trabanti.
Galianemys is an extinct genus of turtle in the family Bothremydidae, discovered in the Kem Kem Beds.
The Kallamedu Formation is a Late Cretaceous (Maastrichtian) geologic formation located in India that forms part of the Ariyalur Group. Dinosaur remains and petrified wood samples are among the known fossils recovered from this formation.
Inaechelys is an extinct genus of bothremydid pleurodiran turtle that was discovered in the Maria Farinha Formation of Brazil. The genus consists solely of type species I. pernambucensis.
Zolhafah is an extinct genus of bothremydid pleurodiran turtle that was discovered in the Western Desert of Egypt. The genus consists solely of type species Z. bella.
Arenila is an extinct genus of bothremydid pleurodiran turtle that was discovered in the Western Desert of Egypt. The genus consists solely of type species A. krebsi.
Phosphatochelys is an extinct genus of bothremydid pleurodiran turtle that was discovered near Oued Zem, Morocco. The genus consists solely of type species P. tedfordi.
Rhothonemys is an extinct genus of bothremydid pleurodiran turtle that was discovered in the Paleogene of Morocco. The genus consists solely of type species R. brinkmani.
Labrostochelys is an extinct genus of bothremydid pleurodiran turtle that was discovered in the Ouled Abdoun Basin, Morocco. The genus consists solely of type species L. galkini.
Sindhochelys is a genus of extinct turtle of the family Bothremydidae. It lived during the early Paleocene in what is known Sindh, Pakistan. The genus was discovered in the Khadro Formation and named in December 2021. The genus represents the first known member of its family in Pakistan. The family Bothremydidae lived from the Cenomanian of the early Cretaceous to the Miocene epoch.
Acleistochelys is an extinct genus of large, bothremydid pleurodiran turtle known from Paleocene deposits in the Teberemt Formation of Mali. The type species, A. maliensis, was named for the country in which it was found. The holotype specimen consists of a nearly complete skull, shell fragments, pelvic fragments, and a cervical vertebra. It is most closely related to another Paleocene Malian side-necked turtle, Azabbaremys.
