Chelidae is one of three living families of the turtle suborder Pleurodira, and are commonly called Austro-South American side-neck turtles. The family is distributed in Australia, New Guinea, parts of Indonesia, and throughout most of South America. It is a large family of turtles with a significant fossil history dating back to the Cretaceous. The family is entirely Gondwanan in origin, with no members found outside Gondwana, either in the present day or as a fossil.
The Cryptodira are a suborder of Testudines that includes most living tortoises and turtles. Cryptodira differ from Pleurodira in that they lower their necks and pull the heads straight back into the shells, instead of folding their necks sideways along the body under the shells' marginals. They include among their species freshwater turtles, snapping turtles, tortoises, softshell turtles, and sea turtles.
Stupendemys is an extinct genus of freshwater side-necked turtle, belonging to the family Podocnemididae. It is the largest freshwater turtle known to have existed, with a carapace over 2 meters long. Its fossils have been found in northern South America, in rocks dating from the Middle Miocene to the very start of the Pliocene, about 13 to 5 million years ago. Male specimens are known to have possessed bony horns growing from the front edges of the shell and the discovery of the fossil of a young adult shows that the carapace of these turtles flattens with age. A fossil skull described in 2021 indicates that Stupendemys was a generalist feeder.
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.
The Madagascan big-headed turtle is a turtle native to the waters of permanent slow moving rivers and lakes in western Madagascar. These turtles are critically endangered and have been evaluated to be the most endangered turtle in the world by a 2018 review. Due to its ancient origins and threatened status, it is ranked as #1 on the EDGE of Existence programme's list of priority reptiles.
The Big-headed Amazon River turtle, also known as the big-headed sideneck, is a species of turtle in the family Podocnemididae. An additional, much larger species is known, the extinct Peltocephalus maturin, joining its living relative in the genus Peltocephalus.
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.
The Qasr el Sagha Formation is a geological formation located in Egypt. The formation is part of the Wadi El Hitan World Heritage Site. The Qasr el Sagha Formation overlies the Birket Qarun Formation and is overlain by the Gebel Qatrani Formation. The sandstones and shales of the formation were deposited in a deltaic to shallow marine environment. It dates to the Late Eocene.
Albertwoodemys is an extinct genus of podocnemidid turtle. From the Early Oligocene in the Jebel Qatrani Formation of Egypt.
Latentemys is an extinct genus of podocnemidid turtle. It is known from Miocene aged sediments of the Moghara Formation in Egypt.
Carbonemys cofrinii is an extinct giant podocnemidid turtle known from the Middle Paleocene Cerrejón Formation of the Cesar-Ranchería Basin in northeastern Colombia. The formation is dated at around 60 to 57 million years ago, starting at about five million years after the KT extinction event.
Araripemydidae is a family of freshwater aquatic turtles belonging to the order Pleurodira, known from the Early Cretaceous of South America and Africa. The family contains two recognised monotypic genera, Araripemys and Taquetochelys, from the Santana Group of Brazil and the Elrhaz Formation of Niger, respectively, which date to the Aptian-Albian stages of the Early Cretaceous. They are consider to be the most basal lineage within the Pelomedusoides. They are thought to have been specialised suction feeders. Laganemys was named in 2013 but was later determined to be synonymous with Taquetochelys.
Bauruemys is an extinct genus of turtles in the family Podocnemididae.
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 2017.
This list of fossil reptiles described in 2020 is a list of new taxa of fossil reptiles that were described during the year 2020, as well as other significant discoveries and events related to reptile paleontology that occurred in 2020.
Bairdemys is an extinct genus of side-necked turtles in the family Podocnemididae. The genus existed from the Late Oligocene to Late Miocene and its fossils have been found in South Carolina, Puerto Rico, Panama and Venezuela. The genus was described in 2002 by Gaffney & Wood and the type species is B. hartsteini.
Motelomama is an extinct genus of bothremydid pleurodiran turtle that was discovered in the Ypresian Salina Group near Negritos, Peru. The genus consists solely of type species M. olssoni.
Caninemys is an extinct genus of large freshwater side-necked turtle, belonging to the family Podocnemididae. Its fossils have been found in Brazil and Colombia, in rocks dating back from the middle to late Miocene.
Amabilis uchoensis is a species of prehistoric pleurodiran turtle from the Late Cretaceous of South America. It is the only species in the genus Amabilis.
Peltocephalus maturin is an extinct species of podocnemidid river turtle closely related to the big-headed Amazon River turtle that lived during the Late Pleistocene and Early Holocene in what is now Brazil. P. maturin is known from a singular lower jaw of enormous size, with estimates suggesting its carapace may have reached lengths of around 1.70 m. This would make it one of the largest freshwater turtles in history, comparable in size to the Paleocene podocnemidid Carbonemys and only exceeded by the Miocene podocnemidid Stupendemys. Like its closest relative, it was likely an omnivore, the narrow cutting surface of its lower jaw unsuited for strict herbivory or durophagy.
