Sea turtles, sometimes called marine turtles, are reptiles of the order Testudines and of the suborder Cryptodira. The seven existing species of sea turtles are the flatback, green, hawksbill, leatherback, loggerhead, Kemp's ridley, and olive ridley sea turtles. All six of the sea turtle species present in US waters are listed as endangered and/or threatened under the Endangered Species Act. The seventh sea turtle species is the flatback, which exists in the waters of Australia, Papua New Guinea and Indonesia. Sea turtles can be separated into the categories of hard-shelled (cheloniid) and leathery-shelled (dermochelyid). There is only one dermochelyid species which is the leatherback sea turtle.
The leatherback sea turtle, sometimes called the lute turtle or leathery turtle or simply the luth, is the largest of all living turtles and the heaviest non-crocodilian reptile, reaching lengths of up to 1.8 metres and weights of 500 kilograms (1,100 lb). It is the only living species in the genus Dermochelys and family Dermochelyidae. It can easily be differentiated from other modern sea turtles by its lack of a bony shell; instead, its carapace is covered by oily flesh and flexible, leather-like skin, for which it is named.
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.
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.
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 4.6 m (15 ft) from head to tail and 2.2–3.2 t 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 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.
Squalodon is an extinct genus of whales of the Oligocene and Miocene epochs, belonging to the family Squalodontidae. Named by Jean-Pierre Sylvestre de Grateloup in 1840, it was originally believed to be an iguanodontid dinosaur but has since been reclassified. The name Squalodon comes from Squalus, a genus of shark. As a result, its name means "shark tooth". Its closest modern relative is the South Asian river dolphin.
Macrochelys is a genus of very large freshwater turtles in the family Chelydridae from Southeastern United States. Only a single extant species was recognized until a 2014 study divided it into two, or possibly three species.
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, time-equivalent beds of the Mooreville Chalk Formation of Alabama and Campanian beds of the Rybushka Formation. Fossil specimens of this species were first collected in 1871, and named by Edward Drinker Cope in 1872. With a total length of 3.9 metres (13 ft), it is the second-largest sea turtle that ever lived, second only to the giant Archelon, and one of the three largest turtle of all time along Archelon and Gigantatypus.
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. but a new fossil named Desmatochelyspadillai in 2015 is estimated to be as old as 120 million years.
Zygophyseter varolai is an extinct sperm whale that lived during the Tortonian age of the Late Miocene 11.2 to 7.6 million years ago. It is known from a single specimen from the Pietra Leccese Formation in Italy. It was a member of a stem group of fossil macroraptorial sperm whales also including Brygmophyseter, Acrophyseter, and Livyatan. It probably grew to be around 6.5 to 7 meters in length and shared some characteristics with other raptorials, such as large teeth with tooth enamel that were functional in both the upper and lower jaws which the modern sperm whale lacks. It also had a beak, the ability to echolocate prey, and could have probably swum faster than the modern-day sperm whale which can reach 4 kilometers per hour (2.5 mph). These were probably used in the capture of large prey, such as large fish, seals, and whales. In fact, its common name, the killer sperm whale, refers to its feeding habits that would have had a resemblance to the modern-day killer whale.
Hesperotestudo is an extinct genus of tortoise native to North and Central America from the Early Miocene to the Late Pleistocene. Species of Hesperotesudo varied widely in size, with a large undescribed specimen from the Late Pleistocene of El Salvador reaching 150 cm (4.9 ft) 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 Hesperotesudo species were extensively covered with large dermal ossicles, which in life were covered in keratin. It has been suggested that species of Hesperotestudo were relatively tolerant of cold weather. Hesperotestudo became extinct at the end of the Pleistocene and beginning of the Holocene co-incident with the arrival of the first humans in North America, and sites have been found where Hesperotestudo were butchered.
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.
Mesodermochelys is an extinct genus of sea turtle known from the Campanian to the Maastrichtian of what today is Japan. 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 that was closely related to the Protostegidae. It has been described as the best representative of Mesozoic dermochelyids.
The turtle shell is a shield for the ventral and dorsal parts of turtles, completely enclosing all the vital organs of the turtle and in some cases even the head. It is constructed of modified bony elements such as the ribs, parts of the pelvis and other bones found in most reptiles. The bone of the shell consists of both skeletal and dermal bone, showing that the complete enclosure of the shell likely evolved by including dermal armor into the rib cage.
Megalochelys is an extinct genus of cryptodiran tortoises that lived from the Miocene to Pleistocene. They are noted for their giant size, which is among the largest of any known testudine, with a maximum carapace length over 2 m (6.5 ft) in M. atlas. During the dry glacial periods it ranged from western India and Pakistan to as far east as Sulawesi and Timor in Indonesia, though the island specimens likely represent distinct species.
The Gran Canaria giant tortoise is an extinct species of cryptodire turtle in the family Testudinidae endemic to the island of Gran Canaria, in the Canary Islands.
Erquelinnesia is an extinct turtle genus from the Cretaceous period, which has been found in fossils. Paleontologist Louis Dollo first described this genus late 19th century from fossilized samples found in the layers of Upper Paleocene / Lower Eocene in Hainaut, Belgium,. Erquelinnesia lived between the Upper Cretaceous and Lower Paleocene ( Danian. Louis Dollo named his discovery as Pachyrhynchus gosseleti in 1886. However, in the following year, the nomenclature was changed by Dollo to Erquelinnesia gosseleti to resolve a conflict with another already existing generic name. Moreover, an additional species was attributed to the genus Erquelinnesia. The North American species called Erquelinnesia molariathat was known only from a fossilized mandible bone has subsequently re-categorized to the genus Euclastes.
This list of fossil reptiles described in 2023 is a list of new taxa of fossil reptiles that were described during the year 2023, as well as other significant discoveries and events related to reptile paleontology that occurred in 2023.
