Monotypic prehistoric reptile 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

Hylonomus (; from Greek , meaning , and , meaning ) is an extinct genus of early (possibly stem group) amniote that lived during the Bashkirian stage of the Late Carboniferous. The genus contains a single species, Hylonomus lyelli.

Placerias (meaning 'broad body') is an extinct genus of dicynodonts that lived during the Carnian and Norian stages of the Triassic period (230–215 million years ago). Placerias belongs to a clade of dicynodonts called Kannemeyeriiformes, which was the last known group of dicynodonts before the taxon became extinct at the end of the Triassic.

Proganochelys is a genus of extinct, primitive stem-turtle. Proganochelys was named by Georg Baur in 1887 as the oldest turtle in existence at the time. The name Proganochelys comes from the Greek word ganos meaning 'brightness', combined with prefix pro, 'before', and Greek base chelys meaning 'turtle'. Proganochelys is believed to have been around 1 meter in size and herbivorous in nature. Proganochelys had been known as the most primitive stem-turtle for over a century, until the novel discovery of Odontochelys in 2008. Odontochelys and Proganochelys share unique primitive features that are

Zapalasaurus is an extinct genus of sauropod dinosaur from the Early Cretaceous-aged La Amarga Formation of what is today Patagonia. The type and only species is Z. bonapartei.

Hesperosuchus is an extinct genus of crocodylomorph reptile that contains a single species, Hesperosuchus agilis. Remains of this pseudosuchian have been found in Late Triassic (Carnian) strata from Arizona and New Mexico. Because of similarities in skull and neck anatomy and the presence of hollow bones, Hesperosuchus was formerly thought to be an ancestor of later carnosaurian dinosaurs, but based on more recent findings and research it is now known to be more closely related to crocodilians rather than dinosaurs.

Aegisuchus is an extinct monospecific genus of giant, flat-headed crocodyliform within the family Aegyptosuchidae. It was found in the Kem Kem Formation of southeast Morocco, which dates back to the Cenomanian age of the Late Cretaceous epoch. The type species Aegisuchus witmeri was named in 2012 by paleontologists Casey Holliday and Nicholas Gardner, who nicknamed it "Shieldcroc" for the shield-like shape of its skull. A. witmeri is known from a single partial skull including the braincase and skull roof.

Bellubrunnus (meaning "the beautiful one of Brunn" in Latin) is an extinct genus of rhamphorhynchid pterosaur from the Late Jurassic (Kimmeridgian stage) of southern Germany. It contains a single species, Bellubrunnus rothgaengeri. Bellubrunnus is distinguished from other rhamphorhynchids by its lack of long projections on the vertebrae of the tail, fewer teeth in the jaws, and wingtips that curve forward rather than sweep backward as in other pterosaurs.

Infernodrakon (meaning "dragon from hell") is a genus of azhdarchid pterosaurs from the Late Cretaceous Hell Creek Formation of Montana, United States. The genus contains a single species, I. hastacollis, known from a single neck vertebra. Based on comparisons with related azhdarchids, it probably had a wingspan of about .

Nipponopterus (meaning "Nippon wing") is an extinct genus of azhdarchid pterosaur that lived during the Late Cretaceous (Turonian to Coniacian ages) in what is now Japan. It is known from a partial cervical (neck) vertebra found in the 'Upper Formation' of the Mifune Group, located in the Kumamoto Prefecture in Kyūshū. The genus contains a single species, Nipponopterus mifunensis, named and described in 2025. It is the first pterosaur to be named from Japan.

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

Inabtanin is an extinct genus of azhdarchoid pterosaurs from the Late Cretaceous Muwaqqar Formation of Jordan. The genus contains a single species, I. alarabia, known from a partial skeleton. Inabtanin represents one of the most complete pterosaur taxa known from the Afro-Arabia region.

Kaganaias (meaning 'Kaga water nymph') is an extinct genus of basal and oldest dolichosaur that lived in what is now Japan during the Early Cretaceous. Kaganaias was semi-aquatic and is the only known aquatic squamate from before the Cenomanian stage of the Cretaceous. It is also the first to be found in an inland area, instead of on the coast where aquatic squamates are commonly found. Its generic name is derived from Kaga Province, the old name for the Ishikawa Prefecture where the specimens were found, while the species name hakusanensis comes from the mountain that gives its name to Hakusa

Klobiodon is a genus of rhamphorhynchid pterosaur from the Middle Jurassic Taynton Limestone Formation of Oxfordshire, England.

Torukjara is an extinct genus of tapejarin pterodactyloid pterosaurs from the Early Cretaceous "Pterosaur Graveyard" (Caiuá Group) of Brazil. The genus contains a single species, T. bandeirae, known from several specimens. The Torukjara fossil material was originally assigned to Caiuajara, but several anatomical differences indicate that both similar species coexisted in the ecosystem.

Galgadraco is an extinct genus of azhdarchid pterosaurs known from the Late Cretaceous (Maastrichtian age) Serra da Galga Formation of Brazil. The genus contains a single species, Galgadraco zephyrius, known from a fragment of the upper beak. It represents the first pterosaur described from the Bauru Group.

Eotephradactylus (meaning "ash-winged dawn goddess") is an extinct genus of pterosaurs known from the Late Triassic of what is now Arizona, United States. The genus contains a single species, Eotephradactylus mcintireae, discovered in 2011 and named in 2025. It is known from part of the lower jaw, isolated teeth, and possibly a wing bone found in the Chinle Formation, which dates to the Norian age. These bones were found in a bone bed in addition to many other species, including various fish, mammal precursors, turtles, and other reptiles.

Propterodactylus (meaning "before Pterodactylus") is an extinct genus of transitional monofenestratan pterosaurs from the Late Jurassic Painten Formation of Germany. The genus contains a single species, P. frankerlae, known from a complete articulated skeleton. Before its naming, Propterodactylus was referred to as the "Painten " in the scientific literature.

Akharhynchus (meaning "another snout") is an extinct genus of tropeognathine pteranodontoid pterosaurs possibly from the Cretaceous Kem Kem Group of Morocco. The genus contains a single species, A. martilli, known from a small fragment of the premaxillae.

Gobiazhdarcho () is an extinct genus of azhdarchid pterosaurs known from the Late Cretaceous Bayanshiree Formation of Mongolia. The genus contains a single species, Gobiazhdarcho tsogtbaatari, known from a three cervical (neck) vertebrae. It was closely related to Quetzalcoatlus and coexisted with Tsogtopteryx, another azhdarchid more closely related to Hatzegopteryx.

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.

Aldabrachampsus is an extinct genus of small horned crocodile known from fragmentary remains. It lived during the Pleistocene on Aldabra Atoll, Seychelles in the western Indian Ocean. The name Aldabrachampsus dilophus means "Two-crested crocodile from Aldabra". It was a small animal, reaching a length of , comparable in size to the smallest extant crocodilians.

Yurlunggur is a genus of fossil snake in the extinct family Madtsoiidae containing the species Yurlunggur camfieldensis known from the Oligocene and Miocene of Australia.

Skiphosoura (meaning "sword tail") is an extinct genus of pterodactyliform pterosaurs from the Late Jurassic Mörnsheim Formation of Germany. The genus contains a single species, S. bavarica, known from a nearly complete skeleton including a partial skull. Skiphosoura exhibits a transitional body morphology between more basal pterosaurs and later pterodactyloids.

Sumpalla is an extinct genus of ophthalmosaurid ichthyosaurs from the Late Jurassic Vaca Muerta Formation of Argentina. It contains a single species, Sumpalla argentina. The holotype was initially believed to have belonged to Aegirosaurus before being placed in a new genus in 2021.

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.

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

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

Melkamter () (meaning "winged lizard") is an extinct genus of monofenestratan pterosaurs from the Early Jurassic Cañadón Asfalto Formation of Argentina. The genus contains a single species, M. pateko, known from a partial skull and fragmentary postcranium. Melkamter represents the oldest known monofenestratan pterosaur in the fossil record.

Parvosuchus (meaning "small crocodile") is an extinct genus of gracilisuchid pseudosuchians from the Middle–Late Triassic Santa Maria Formation (Paraná Basin) of Brazil. The genus contains a single species, P. aurelioi, known from a cranium and partial skeleton.

Tsogtopteryx () is an extinct genus of azhdarchid pterosaurs known from the Late Cretaceous Bayanshiree Formation of Mongolia. The genus contains a single species, Tsogtopteryx mongoliensis, known from most of a cervical (neck) vertebra. It was closely related to Hatzegopteryx, and coexisted with Gobiazhdarcho, another azhdarchid more closely related to Quetzalcoatlus.

Asprosaurus () is an extinct genus of anguimorph lizard from the Late Cretaceous (Campanian) of South Korea. The genus contains a single species, A. bibongriensis, which is the first Mesozoic lizard to have been discovered on the Korean peninsula. Initially classified as a possible monstersaurian, Asprosaurus has been subsequently suggested to be a probable mosasauroid, an extinct group of marine lizards during the Late Cretaceous.

Saratovia is a genus of targaryendraconian pterosaurs that lived during the Late Cretaceous in what is now Russia. The genus contains a single species, S. glickmani, known from a partial lower jawbone, and is named after the city of Saratov, where the specimen was found, and its discover Leonid S. Glickman. The fossil comes from sedimentary rocks of the Melovatka Formation. Uncovered in the 1940s, the only specimen was assigned to various genera such as Ornithocheirus, Anhanguera and Coloborhynchus before being recognized as a new taxon and named in 2025. Likewise, though long thought to belon

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.