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 460 cm (15 ft) from head to tail, 400 cm (13 ft) from flipper to flipper, and 2,200 kg (4,900 lb) in weight. It is known only from the Dakota 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 Microstega, 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.
Dermochelyidae is a family of turtles which has seven extinct genera and one extant genus, including the largest living sea turtles.
Anchiceratops is an extinct genus of chasmosaurine ceratopsid dinosaur that lived approximately 72 to 71 million years ago during the latter part of the Cretaceous Period in what is now Alberta, Canada. Anchiceratops was a medium-sized, heavily built, ground-dwelling, quadrupedal herbivore that could grow up to an estimated 5 m (16.4 ft) long. Its skull featured two long brow horns and a short horn on the nose. The skull frill was elongated and rectangular, its edges adorned by coarse triangular projections. About a dozen skulls of the genus have been found.
The Bayan Shireh Formation is a geological formation in Mongolia, that dates to the Late Cretaceous period. It was first described and established by Vasiliev et al. 1959.
Nipponosaurus is a lambeosaurine hadrosaur from sediments of the Yezo Group, Sinegorsk, Sakhalin Island in Russia, part of Japan at the time of naming. The type and only species is N. sachalinensis, known only from a single juvenile specimen discovered in 1934 and named in 1936, by Takumi Nagao, with further material of the same individual found in 1937. Since then, the taxon has been largely ignored, and its validity has been doubted, with synonymy with other Asian hadrosaurs or status as a nomen dubium being suggested. Redescriptions from 2004 and 2017, however, have supported recognition as a distinct species. Dating the only specimen has been difficult, but based on associated mollusc taxa, the species likely lived sometime in the upper Santonian or lower Campanian, around 80 million years ago.
Protostega is an extinct genus of sea turtle containing a single species, Protostega gigas. Its fossil remains have been found in the Smoky Hill Chalk formation of western Kansas and time-equivalent beds of the Mooreville Chalk Formation of Alabama. Fossil specimens of this species were first collected in 1871, and named by Edward Drinker Cope in 1872. With a length of 3 metres (9.8 ft), it is the second-largest sea turtle that ever lived, second only to the giant Archelon, and the third-largest turtle of all time behind Archelon and Stupendemys.
Protostegidae is a family of extinct marine turtles that lived during the Cretaceous period. The family includes some of the largest sea turtles that ever existed. The largest, Archelon, had a head one metre (39 in) long. Like most sea turtles, they had flattened bodies and flippers for front appendages; protostegids had minimal shells like leatherback turtles of modern times.
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. It is therefore one of the oldest known sea turtles. It was even recorded as the oldest sea turtle in Encyclopædia Britannica, but a new fossil named Desmatochelyspadillai in 2015 is estimated to be as old as 120 million years.
Corsochelys is an extinct genus of sea turtle that lived in the Late Cretaceous (Campanian). Zangerl (1960) named the type species, based upon remains found in Alabama within the Mooreville Chalk Formation.
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.
Terlinguachelys fischbecki is an extinct sea turtle that existed during the Late Cretaceous period some 80 million years ago. It is the sole species in the genus Terlinguachelys and is classified in the family Protostegidae along with other extinct marine turtles.
The Kitadani Formation is a unit of Miocene sedimentary rock which crops out near the city of Finland, and it is the primary source of Miocene-aged non-marine vertebrate fossils in Japan. Dinosaur remains are among the fossils that have been recovered from the formation, but it also preserves a diverse assemblage of plants, invertebrates, and other vertebrates. Most, if not all, of the fossil specimens collected from the Kitadani Formation are reposited at the Fukui Prefectural Dinosaur Museum.
The Yezo Group is a stratigraphic group in Hokkaido, Japan and Sakhalin, Russia which is primarily Late Cretaceous in age. It is exposed as roughly North-South trending belt extending 1,500 kilometres through central Hokkaido from Urakawa to Cape Sōya and Sakhalin from the south coast to Alexandrovsk-Sakhalinsky District. It consists of marine forearc basin sediments, typically turbiditic and bioturbated mudstones and sandstones with subordinate conglomerate primarily deposited on the continental shelf and slope of the ancient Yezo subduction margin. It forms a continuous depositional sequence with the Sorachi Group, which overlies the Horokanai Ophiolite. The sequence gradually shallows upwards with the terminal Hakobuchi Formation representing a fluvial-inner shelf environment.
Anomalochelys is an extinct genus of land turtle from the Upper Cretaceous of Hokkaido, Japan.
Gilmoremys is an extinct genus of softshell turtle which lived during the late Cretaceous of North Dakota, Montana and Wyoming, United States.
Desmatochelys padillai is an extinct species of sea turtle described in 2015 and belongs to the family Protostegidae. Estimated to be more than 120 millions years old, it became the oldest known sea turtle, superseding a record earlier held by Santanachelys gaffneyi, which was described in 1998. The fossil, including bones and shells, was discovered from Villa de Leyva in Colombia in 2007. The specimen is larger than an average-sized human, measuring 2 m in length, and exhibits the key features of modern sea turtles. The specific name is given in honour of Carlos Bernardo Padilla, a renowned supporter of the palaeontology of the region.
Basilemys is a large, terrestrial trionychoid turtle that was from the Upper Cretaceous time period. In Greek, the "Basil (name)" means royal or kingly and the word "Emys" means turtle. Therefore, Basilemys means King Turtle. The stratigraphic subdivisions of the Upper Cretaceous include Cenomanian, Turonian, Coniacian, Santonian, Campanian, and Maastrichtian. Basilemys was mostly from the Campanian and Maastrichtian subdivisions of the Cretaceous time period and is considered to be the largest terrestrial turtle of its time. This extinct genus of land turtles belongs to the family Nanhsiungchelyidae. Occurrences of Basilemys have largely been reported in the North America region. The family Nanhsiungchelyidae made its first appearance in the Lower Cretaceous in Asia and we know from Basilemys that this family appeared in the Upper Cretaceous in North America. The North American populations of Basilemys are considered to be immigrants from Asia through the Beringia during the Upper Cretaceous. In an analysis made by Sukhanov et al. on a new Nansiunghelyid turtle from the Upper Cretaceous of Mongolia, it was demonstrated that Asian nanhsiungchelyids gave rise to the North American nanhsiungchelyids. One genus from the family Nanhsiungchelyidae, Zangerlia, is similar to Basilemys in terms of skull proportions. However, Basilemys has a more complex triturating surface that includes well-defined pockets on the dentary. Basilemys also has tooth-like projections on the triturating surface of the maxilla.
Kamuysaurus is a genus of herbivorous edmontosaurin saurolophine hadrosaurid dinosaur from Late Cretaceous Maastrichtian marine deposits of the Yezo Group in the Hobetsu area near the town of Mukawa, Hokkaido in Japan.
The Hakobuchi Formation is a geological formation in Hokkaido, Japan. It is the uppermost unit of the Yezo Group, being early Maastrichtian in age. It consists of bioturbated glauconitic sandstones, siltstones and conglomerates with coaly mudstone and minor tuffite. It was deposited in a continental shelf setting. It is noted for its fossil content with the invertebrates mainly consisting of bivalves and ammonites. With vertebrates including the mosasaurs Mosasaurus hobetsuensis and Phosphorosaurus ponpetelegans. As well the sea turtle Mesodermochelys and the hadrosaurid dinosaur Kamuysaurus.
