Prehistoric turtle genera

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 from head to tail and 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 1896 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

Meiolania is an extinct genus of meiolaniid stem-turtle native to Australasia throughout much of the Cenozoic. Meiolania was a large turtle, with the shell alone ranging from in length. Four species are currently recognized, although the validity of two of them is disputed. Meiolania was first described as a species of lizard related to Megalania by Richard Owen towards the end of the 19th century, before the continued discovery of additional fossils solidified its placement as a kind of turtle.

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 202

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 to approximately 60 to 57 million years ago, beginning about five million years after the KT extinction event.

Protostega ('first roof') is an extinct genus of sea turtle containing a single species, Protostega gigas. The species lasted from the Coniacian to the Campanian stages of the Late Cretaceous. Its fossil remains have been found in the Smoky Hill Chalk formation of western Kansas (Hesperornis zone, dated to 83.5 million years ago), time-equivalent beds of the Mooreville Chalk Formation of Alabama and Campanian beds of the Rybushka Formation (Saratov Oblast, Russia). It is also known from rocks in Canada, with these sediments dating to the middle Campanian due to them being found in the Pembina

Niolamia is an extinct genus of South American meiolaniid turtle with a long and complex history. Like its relatives, Niolamia was a robust and heavily armored terrestrial turtle with large, horn like scales covering its head and a tail encased by rings of bone. This heavily armored build may have served the animal during intraspecific combat during courtship, though such encounters likely did not involve the horns and frill, which are thought to serve more of a display function. Scans of the skull reveal that Niolamia likely had a great sense of smell but only low frequency hearing, indicatin

Desmatochelys (from Greek δεσμός desmos 'link' + χέλῡς khelus 'tortoise') 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.

Megalochelys ("great turtle") is an extinct genus of tortoises that lived from the Miocene to Pleistocene. They are noted for their giant size, the largest known for any tortoise, with a maximum carapace length of over 2 m (6.5 ft) in M. atlas. The genus ranged from western India and Pakistan to as far east as Sulawesi and Timor in Indonesia, though the island specimens likely represent distinct species.

Kayentachelys ("Kayenta turtle") is an extinct genus of turtle known only from the "silty facies" of the Lower Jurassic Kayenta Formation in northeastern Arizona on the lands of the Navajo Nation.

Santanachelys gaffneyi is an extinct species of sea turtle. It is the only species in the genus Santanachelys, which itself is a member of the extinct family Protostegidae. The species was first described from a 20-centimeter long fossil specimen unearthed in 1998 from the Santana Formation of eastern Brazil. From the rock layer from which it was excavated, it was determined that the specimen was from the Early Cretaceous period (112 million years old). It is therefore one of the oldest known sea turtles. but a new fossil named Desmatochelys padillai in 2015 is estimated to be as old as 120 mi

Ocepechelon is an extinct genus of giant protostegid sea turtle known from the Late Cretaceous (late Maastrichtian stage, 67 Myr) of Morocco. The feeding apparatus of Ocepechelon, a bony pipette-like snout, is unique among tetrapods and shares unique convergences with both syngnathid fishes (unique long tubular bony snout ending in a rounded and forward directed mouth) and beaked whales (large size and elongated edentulous jaws).

Kallokibotion is an extinct genus of stem-turtle from the Upper Cretaceous (Santonian-Maastrichtian, 86–66 million years ago), known from fossils found in Romania. One species is known, Kallokibotion bajazidi, which was named by Franz Nopcsa after his lover Bajazid Doda. It literally means 'beautiful box of Bajazid'; Nopcsa chose the name because, in the words of British palaeontologist Gareth Dyke, "the shape of the shell reminded him of Bajazid's arse". A second undescribed species is known from the Santonian of Hungary. Turtles similar to Kallokibotion were reported from the Paleocene of Fr

left|thumb|Skull in multiple views Angolachelys is an extinct genus of African marine turtle which existed in Angola during the Turonian stage of the Late Cretaceous. The type species is Angolachelys mbaxi. The type MGUAN-PA includes skull, jaw, and postcranial fragments found in the Tadi Beds of the Itombe Formation.

Toxochelys () is an extinct genus of marine turtle from the Late Cretaceous period. It is the most commonly found fossilized turtle species in the Smoky Hill Chalk, in western Kansas.

Puppigerus is an extinct genus of sea turtle from the Eocene. It is known from finds in the United States, the United Kingdom, Belgium, Denmark, and Uzbekistan.

Allopleuron (meaning "other side") is a genus of extinct sea turtle, which measured long in life. The type species is Allopleuron hofmanni. It is a basal member of the clade Pancheloniidae, closely related to Protosphargis. Similar to Protosphargis, it was characterized by shell reduction.

Titanochelon is an extinct genus of giant tortoises known from the Early Miocene to the beginning of the Pleistocene in Europe, extending from the Iberian Peninsula to Anatolia, as well as possibly North Africa. Some members of the genus were larger than extant giant tortoises, with a shell length of up to .

Axestemys is an extinct genus of softshell turtle that lived from the Late Cretaceous to the Eocene in western North America and Europe.

Manchurochelys is an extinct genus of turtle. It existed during the early Cretaceous of what is now northeast China. It has been found in the Jianshangou Bed of West Liaoning's Yixian Formation. However, it is a rarely found fossil. left|thumb|Skull and neck Manchurochelys was first named by Endo and Shikama in 1942, and contains the single species, M. manchoukuoensis (sometimes misspelled M. manchouensis). A second species, M. liaoxensis, was named in 1995 but was later shown to be a species of Ordosemys. It has been occasionally placed in the family Sinemydidae, although it is said to more l

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.

Stylemys (meaning "pillar turtle") is the first fossil genus of dry land tortoise belonging to the order Testudines discovered in the United States. The genus lived in temperate to subtropical areas of North America, Europe, and Asia, based on fossil distribution. The genus was first described in 1851 by Joseph Leidy. The tortoise was common in the prehistoric Badlands, especially Nebraska and South Dakota. The species has also been found in the formations in and around Badlands National Park. Fossil fragments have also been found in the Palm Park Formation of New Mexico.

Polysternon is a genus of turtles in the extinct family Bothremydidae. It was described by Portis in 1882, and contains the species P. provinciale (originally placed in the genus Pleurosternon), which existed during the Cretaceous of what is now France and a new species, P. isonae, from the Late Maastrichtian of Spain.

Allaeochelys is an extinct genus of carettochelyid turtle, known from the Eocene to Miocene of Europe, Asia, North America and Africa.

Xinjiangchelys is an extinct genus of xinjiangchelyid turtle known from the Middle Jurassic to Early Cretaceous of China and Kyrgyzstan. It is known from over 11 different species.

Warkalania is an extinct genus of Australian meiolaniid turtle from the Oligocene or early Miocene of Riversleigh, Queensland. While other meiolaniids are known for their elaborate headcrests or long horns, Warkalania only possesses very short horns that form a somewhat continuous ridge across the back of the head. The only known species of this genus, Warkalania carinaminor, is the oldest named meiolaniid turtle of Australia.

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.

Araripemys is an extinct marine turtle genus from 112 to 109 million years ago, in the Early Cretaceous Crato and Romualdo Formations of the Araripe Basin in northeastern Brazil. It is one of the oldest known pleurodires. thumb|left|Araripemys barretoi

Glyptops is an extinct genus of pleurosternid freshwater turtle known from the Late Jurassic of North America.

Hesperotestudo ("Western turtle") is an extinct genus of tortoise native to North and Central America (ranging as far south as Costa Rica) from the Early Miocene to the Late Pleistocene. Species of Hesperotestudo varied widely in size, with a large undescribed specimen from the Late Pleistocene of El Salvador reaching in carapace length, larger than that of extant giant tortoises. Historically considered a subgenus of Geochelone, it is now considered to be distantly related to that genus. Its relationships with other tortoises are uncertain. The exposed areas of the bodies of Hesperotestudo sp

Anosteira is an extinct genus of carettochelyid turtle from the Eocene to the Oligocene of Asia and North America.

Leyvachelys is an extinct genus of turtles in the family Sandownidae from the Early Cretaceous (Late Aptian to Early Albian) of the present-day Altiplano Cundiboyacense, Eastern Ranges, Colombian Andes. The genus is known only from its type species, Leyvachelys cipadi, described in 2015 by Colombian paleontologist Edwin Cadena. Fossils of Leyvachelys have been found in the fossiliferous Paja Formation, close to Villa de Leyva, Boyacá, after which the genus is named. The holotype specimen is the oldest and most complete sandownid turtle found to date.

Leviathanochelys is an extinct genus of giant sea turtle from the Middle Campanian of northern Spain. Although only known from the rear end of the carapace and the connecting pubic bones, these elements clearly show that they belonged to a turtle of great size, comparable in dimensions to the giant Archelon and Protostega from the Western Interior Seaway of the USA. This makes Leviathanochelys the first giant sea turtle known from Europe and one of the largest known turtles of all time. This great size was evolved independently from the American protostegid turtles and was likely an adaptation

Patagoniaemys is an extinct genus of stem turtle known from the late Cretaceous (Campanian to Maastrichtian age) of central Patagonia, Argentina. The genus contains two species: the type species, Patagoniaemys gasparinae, named in 2011, and a second species, Patagoniaemys aeschyli, named in 2026. It is a relatively large taxon with an oval-shaped carapace that has a large nuchal notch and many pits and grooves over its surface.

Plastomenus is an extinct genus of turtle that inhabited western North America during the early Paleogene period.

Liaochelys is an extinct genus of sinemydid turtle which existed in western Liaoning, China during the early Cretaceous epoch. It was first named by Chang-Fu Zhou in 2010 and the type species is Liaochelys jianchangensis.

Pneumatoarthrus is an extinct genus of sea turtle known from the Late Cretaceous (early Maastrichtian) Mount Laurel Formation of Monmouth County, New Jersey. Many experts consider Pneumatoarthrus a senior synonym of Archelon. If this classification is correct, it would have reached 4-5 meters in length with a fin span of up to 5 meters, and weighed over 2.3 tons. Only a single species, P. peloreus, is known.

Gigantatypus is an extinct late Maastrichtian sea turtle that lived in the southern regions of the Tethys Ocean about off the north eastern margins of Cretaceous Africa immediately before the Cretaceous–Paleogene extinction events . Fossil remains of Gigantatypus are so far only represented in sediments from the Muwaqqar Chalk-Marl Formation of Jordan. Estimated at over in length, members of this genus reached remarkably large proportions equivalent to that of or possibly even exceeding Archelon Wieland, 1896, considered as the largest marine turtles to ever roam the oceans of the world.

Eosphargis (from Greek eos, meaning "dawn", and sphargis, the Greek word for the leatherback turtle) is an extinct genus of sea turtles from the late Paleocene and early Eocene of western Europe and eastern North America. It is a member of the family Dermochelyidae, which also includes the modern leatherback sea turtle (Dermochelys coriacea), of which it is the earliest known definitive member.

Sahonachelys is an extinct genus of pelomedusoid turtle from the Late Cretaceous (Maastrichtian) Maevarano Formation of Madagascar. The genus contains a single species, Sahonachelys mailakavava.

Bothremys is an extinct genus of bothremydid pleurodiran turtle that was discovered near Gloucester, New Jersey. The genus consists of type species B. cooki, B. arabicus, B. kellyi, and B. maghrebiana.

Psephophorus is an extinct genus of sea turtle that lived from the Oligocene to the Pliocene. Its remains have been found in Europe, Africa, North America, and New Zealand. It was first named by Hermann von Meyer in 1847, and contains eight species, P. polygonus, P. calvertensis, P. eocaenus, P. oregonesis, P. californiensis, P. rupeliensis, P. scaldii, and P. terrypratchetti.

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

Pleurosternon is an extinct genus of freshwater pleurosternid turtle from the latest Jurassic to earliest Cretaceous of Europe. Its type species, P. bullockii, was described by the paleontologist Richard Owen (noted for coining the word Dinosauria) in 1853. Since then, and throughout the late 19th century, many fossil turtles were incorrectly assigned to this genus, though only two are currently considered valid.

Protosphargis is an extinct genus of sea turtle from the Upper Cretaceous of Italy. It was first named by Capellini in 1884. thumb|left|Protosphargis veronensis carapace, ventral view

Bauruemys is an extinct genus of turtles in the family Podocnemididae.

Owadowia is a genus of extinct thalassochelydian turtle from the Late Jurassic of Poland. The type and only species is Owadowia borsukbialynickae, named by Szczygielski and colleagues in 2017 for a partial lower jaw, coracoid, ilium and femur from the early Tithonian Kcynia Formation. The limited material means that it is difficult to compare Owadowia to its relatives, and it may not be a unique taxon. The genus lacks the features diagnostic to its parent clade Thalassochelydia, has similarities to Solnhofia and Portlandemys as well as being a Late Jurassic marine turtle like the remainder of

Chupacabrachelys is an extinct genus of bothremydid turtle which existed in western Texas, United States during the late Cretaceous period (Campanian age). Its fossils were discovered in Aguja Formation in the Big Bend region, and its type example is one of the most complete bothremydid specimens known. It was first named by Thomas M. Lehman and Steven L. Wick in 2010 and the type species is Chupacabrachelys complexus. Chupacabrachelys was named after the cryptid of the same name from Mexican folklore.

Chelosphargis is an extinct genus of sea turtle from Upper Cretaceous of Alabama. Only one species has been described, Chelosphargis advena.

Ninjemys oweni is an extinct large meiolaniid stem-turtle from Pleistocene Queensland and possibly New South Wales (Australia). It overall resembled its relative, Meiolania, save that the largest pair of horns on its head stuck out to the sides, rather than point backwards, the larger scales at the back of its skull and the tail club which is made up of only two tail rings rather than four. With a shell length of approximately it is a large turtle and among the largest meiolaniids. Ninjemys is primarily known from a well preserved skull and associated tail armor, which were initially thought t

Mesodermochelys is an extinct genus of sea turtle known from the Campanian to the Maastrichtian (Late Cretaceous) of what today is Japan and from the Maastrichtian of Chile. One species is known, the type species M. undulatus; it was given its binomial name by Ren Hirayama and Tsutomu Chitoku in 1996. Studies of its skull indicate that it was a primitive member of the Dermochelyidae (leatherback turtle family) that was closely related to the Protostegidae. It has been described as the best representative of Mesozoic dermochelyids.