20-597: Pistosauroidea is a group of marine reptiles within the superorder Sauropterygia that first appeared in the latter part of the Early Triassic and were the ancestors of plesiosaurs . Pistosauroids are rare in Triassic marine assemblages, and are represented by only a few fossils from central Europe , the United States , and China . Recent phylogenetic analyses consider the Triassic pistosauroids to be
40-607: A marine environment . Only about 100 of the 12,000 extant reptile species and subspecies are classed as marine reptiles, including marine iguanas , sea snakes , sea turtles and saltwater crocodiles . The earliest marine reptile was Mesosaurus (not to be confused with Mosasaurus ), which arose in the Permian period of the Paleozoic era. During the Mesozoic era, many groups of reptiles became adapted to life in
60-631: A paraphyletic grouping, meaning that they do not form a true clade . Plesiosauria is now placed within Pistosauroidea, while the traditional pistosauroids are successively more basal , or primitive, sauropterygians. Below is a cladogram of pistosauroid relationships from Cheng et al. (2006): Placodontia [REDACTED] Pachypleurosauria [REDACTED] Nothosauria [REDACTED] Corosaurus Cymatosaurus Pistosaurus [REDACTED] Yunguisaurus Augustasaurus Plesiosauria [REDACTED] Below
80-1097: A marine lifestyle that they were incapable of venturing onto land and gave birth in the water. Others, such as sea turtles and saltwater crocodiles, return to shore to lay their eggs. Some marine reptiles also occasionally rest and bask on land. Most species of marine reptiles are considered endangered to some degree. All but one species of sea turtles are endangered due to destruction of nesting habitats on coastal lands, exploitation, and marine fishing; many species of sea snakes are threatened or endangered due to commercial exploitation (sale of skins) and pollution especially in Asia; marine iguanas are threatened due to their very limited habitation range. Saltwater crocodiles are at low risk for extinction. Sea turtles Chelonii - Oppel, 1811 Chlonopteria - Rafinesque, 1814 Cheloniae - Schmid, 1819 Edigitata - Haworth, 1825 Oiacopodae - Wagler, 1828 Pterodactyli - Mayer, 1849 Sea turtles (superfamily Chelonioidea ), sometimes called marine turtles , are reptiles of
100-556: Is a cladogram showing the phylogenetic relationships of living and extinct sea turtles in the Chelonioidea based on Evers et al. (2019): † Toxochelys † Protostegidae [REDACTED] † Corsochelys Dermochelyidae [REDACTED] † Nichollsemys † Allopleuron Cheloniidae [REDACTED] † Argillochelys † Procolpochelys † Eochelone † Puppigerus † Ctenochelys † Peritresius † Cabindachelys An alternate phylogeny
120-559: Is a cladogram of pistosauroid relationships from Ketchum & Benson, 2011: Cymatosaurus " Pistosaurus postcranium" Bobosaurus Pistosaurus [REDACTED] Yunguisaurus Augustasaurus Plesiosauria [REDACTED] [REDACTED] [REDACTED] [REDACTED] This article about a prehistoric reptile is a stub . You can help Misplaced Pages by expanding it . Marine reptile Marine reptiles are reptiles which have become secondarily adapted for an aquatic or semiaquatic life in
140-625: Is possible to tell male turtles from female turtles by their long tails with a cloacal opening near the tip. Adult female sea turtles have shorter tails, with a cloacal opening near the base. Hatchling and sub-adult turtles do not exhibit sexual dimorphism ; it is not possible to determine their sex by looking at them. In general, sea turtles have a more fusiform body plan than their terrestrial or freshwater counterparts. This tapering at both ends reduces volume and means that sea turtles cannot retract their head and limbs into their shells for protection, unlike many other turtles and tortoises. However,
160-466: Is the smallest sea turtle species, to 120 cm (3.9 ft) long in the case of the green turtle, the second largest. The skulls of sea turtles have cheek regions that are enclosed in bone. Although this condition appears to resemble that found in the earliest known fossil reptiles (anapsids), it is possible it is a more recently evolved trait in sea turtles, placing them outside the anapsids. Sea turtles, along with other turtles and tortoises, are part of
180-468: The IUCN Red List of Threatened Species. The flatback turtle is found only in the waters of Australia, Papua New Guinea, and Indonesia. Sea turtles can be categorized as hard-shelled ( cheloniid ) or leathery-shelled ( dermochelyid ). The only dermochelyid species of sea turtle is the leatherback. For each of the seven species of sea turtles, females and males are the same size. As adults, it
200-608: The sister group to the Chelonoidea, or an unrelated turtle lineage that convergently evolved similar adaptations. The earliest "true" sea turtle that is known from fossils is Nichollsemys from the Early Cretaceous ( Albian ) of Canada . In 2022, the giant fossil species Leviathanochelys was described from Spain . This species inhabited the oceans covering Europe in the Late Cretaceous and rivaled
220-567: The Cenozoic, most importantly the sea turtles . Other Cenozoic marine reptiles included the bothremydids , palaeophiid snakes, a few choristoderes such as Simoedosaurus and dyrosaurid crocodylomorphs. Various types of marine gavialid crocodilians remained widespread as recently as the Late Miocene. Some marine reptiles, such as ichthyosaurs, plesiosaurs, metriorhynchid thalattosuchians, and mosasaurs became so well adapted to
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#1732797166236240-566: The concurrent giant protostegids such as Archelon and Protostega as one of the largest turtles to ever exist. Unlike the protostegids, which have an uncertain relationship to modern sea turtles, Leviathanochelys is thought to be a true sea turtle of the superfamily Chelonioidea. Sea turtles' limbs and brains have evolved to adapt to their diets. Their limbs originally evolved for locomotion, but more recently evolved to aid them in feeding. They use their limbs to hold, swipe, and forage their food. This helps them eat more efficiently. Below
260-479: The first marine turtle is Angolachelys , from the Turonian of Angola. A lineage of unrelated marine testudines, the pleurodire (side-necked) bothremydids , also survived well into the Cenozoic. Other pleurodires are also thought to have lived at sea, such as Araripemys and extinct pelomedusids . Modern sea turtles are not descended from more than one of the groups of sea-going turtles that have existed in
280-561: The lineage ( Panchelonioidea ) leading to modern sea turtles was possibly Desmatochelys padillai from the Early Cretaceous. Desmatochelys was a protostegid , a lineage that would later give rise to some very large species but went extinct at the end of the Cretaceous. Presently thought to be outside the crown group that contains modern sea turtles (Chelonioidea), the exact relationships of protostegids to modern sea turtles are still debated due to their primitive morphology; they may be
300-534: 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 . Six of the seven sea turtle species, all but the flatback, are present in U.S. waters, and are listed as endangered and/or threatened under the Endangered Species Act . All but the flatback turtle are listed as threatened with extinction globally on
320-609: The order Testudines . All species except the leatherback sea turtle are in the family Cheloniidae . The superfamily name Chelonioidea and family name Cheloniidae are based on the Ancient Greek word for tortoise: χελώνη ( khelōnē ). The leatherback sea turtle is the only extant member of the family Dermochelyidae . Fossil evidence of marine turtles goes back to the Late Jurassic (150 million years ago) with genera such as Plesiochelys , from Europe. In Africa,
340-462: The past; they instead constitute a single radiation that became distinct from all other turtles at least 110 million years ago. Their closest extant relatives are in fact the snapping turtles (Chelydridae), musk turtles (Kinosternidae), and hickatee ( Dermatemyidae ) of the Americas, which alongside the sea turtles constitute the clade Americhelydia . The oldest possible representative of
360-461: The seas, including such familiar clades as the ichthyosaurs , plesiosaurs (these two orders were once thought united in the group "Enaliosauria", a classification now cladistically obsolete), mosasaurs , nothosaurs , placodonts , sea turtles , thalattosaurs and thalattosuchians . Most marine reptile groups became extinct at the end of the Cretaceous period, but some still existed during
380-468: The streamlined body plan reduces friction and drag in the water and allows sea turtles to swim more easily and swiftly. The leatherback sea turtle is the largest sea turtle, reaching 1.4 to more than 1.8 m (4.6 to 5.9 ft) in length and weighing between 300 and 640 kg (661 to 1,411 lbs). Other sea turtle species are smaller, ranging from as little as 60 cm (2 ft) long in the case of the Kemp's ridley, which
400-508: Was proposed by Castillo-Visa et al. (2022): † Toxochelyidae † Protostegidae † Corsochelys † Eosphargis Dermochelys † Nichollsemys † Leviathanochelys † Allopleuron † Procolpochelys † Argillochelys † Eochelone † Puppigerus † Cabindachelys † Ctenochelys † Peritresius Natator Eretmochelys Chelonia Lepidochelys kempii Caretta Lepidochelys olivacea Sea turtles can be found in all oceans except for
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