Yaverland is a village on the Isle of Wight, just north of Sandown on Sandown Bay. It has about 200 houses. About 1⁄3 of a mile away from the village is Church. Holotype fossils have been discovered here of a pterosaur, Caulkicephalus; the White Air extreme sports festival was held annually at Yaverland pay and display car park between 1997 and 2008, but moved to Brighton for 2009. The older part of the village is spread along the road to Bembridge by the Norman Church; the newer part is along the seafront, consisting of a bungalow estate. The name appears to come from a local rendition of "over land" - being the land over the once-tidal causeway. An alternative derivation is from "Yar Island". In the fields below Yaverland the archaeological television programme Time Team discovered a Roman smithy. In 1545 a battle took place in Yaverland between local levies; the French were crossing Culver Down from their landing at Whitecliff Bay in order to attack Sandown Castle and link up with a force from Bonchurch.
The French fought their way into Sandown but were defeated at Sandown Castle under construction in the sea. The Isle of Wight Zoo is in Yaverland; the zoo is noted for its collection of rescued tigers and realistic and spacious enclosures for them. The zoo inhabits much of the converted buildings of the Granite Fort built by Lord Palmerston as a defense against the French in 1860; the grounds were used by the military during World War II as part of the Pluto pipeline to send oil under the English Channel to France to fuel the Allied war efforts. By the sea is the Yaverland Sailing and Boat Club and along the seashore are fossil-bearing beds, which may be explored by guided walks from Dinosaur Isle. A holiday camp is located further north in the village, was once the site of Yaverland Battery. In November 2008, the Isle of Wight Council opened a new public toilet block which runs from renewable energy generated on-site, it is thought to be one of the "greenest" facilities in the UK. Southern Vectis bus route 8 links the village with the towns of Newport, Ryde and Sandown, including intermediate towns.
Wightbus run route 22 around Culver Way to Sandown, after Southern Vectis withdrew route 10 from the area. St. John the Baptist Church, Yaverland Yaverland, Isle of Wight, UK, BBC, h2g2, 14 March 2000 Isle of Wight Zoo website IOW Council beach information
A swamp is a wetland, forested. Many swamps occur along large rivers where they are critically dependent upon natural water level fluctuations. Other swamps occur on the shores of large lakes; some swamps have hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodic inundation or soil saturation. The two main types of swamp swamp forests and "transitional" or shrub swamps. In the boreal regions of Canada, the word swamp is colloquially used for what is more termed a bog, fen, or muskeg; the water of a swamp may be brackish water or seawater. Some of the world's largest swamps are found along major rivers such as the Amazon, the Mississippi, the Congo. A marsh is a wetland composed of grasses and reeds found near the fringes of lakes and streams, serving as a transitional area between land and aquatic ecosystems. A swamp is a wetland composed of shrubs found along large rivers and lake shores. Swamps are characterized by slow-moving to stagnant waters.
Many adjoin rivers or lakes. Swamps are features of areas with low topographic relief. Humans have drained swamps to provide additional land for agriculture and to reduce the threat of diseases borne by swamp insects and similar animals. Many swamps have undergone intensive logging, requiring the construction of drainage ditches and canals; these ditches and canals contributed to drainage and, along the coast, allowed salt water to intrude, converting swamps to marsh or to open water. Large areas of swamp were therefore degraded. Louisiana provides a classic example of wetland loss from these combined factors. Europe has lost nearly half its wetlands. New Zealand lost 90 percent of its wetlands over a period of 150 years. Ecologists recognise that swamps provide valuable ecological services including flood control, fish production, water purification, carbon storage, wildlife habitat. In many parts of the world authorities protect swamps. In parts of Europe and North America, swamp restoration projects are becoming widespread.
The simplest steps to restoring swamps involve plugging drainage ditches and removing levees. Swamps and other wetlands have traditionally held a low property value compared to fields, prairies, or woodlands, they have a reputation for being unproductive land that cannot be utilized for human activities, other than hunting and trapping. Farmers, for example drained swamps next to their fields so as to gain more land usable for planting crops. Many societies now realize that swamps are critically important to providing fresh water and oxygen to all life, that they are breeding grounds for a wide variety of species. Indeed, floodplain swamps are important in fish production. Government environmental agencies are taking steps to protect and preserve swamps and other wetlands. In Europe, major effort is being invested in the restoration of swamp forests along rivers. Conservationists work to preserve swamps such as those in northwest Indiana in the United States Midwest that were preserved as part of the Indiana Dunes.
The problem of invasive species has been put into greater light such as in places like the Everglades. Swamps can be found on all continents except Antarctica; the largest swamp in the world is the Amazon River floodplain, significant for its large number of fish and tree species. The Sudd and the Okavango Delta are Africa's best known marshland areas; the Bangweulu Floodplains make up Africa's largest swamp. The Tigris-Euphrates river system is a large swamp and river system in southern Iraq, traditionally inhabited in part by the Marsh Arabs. In Asia, tropical peat swamps are located in mainland East Southeast Asia. In Southeast Asia, peatlands are found in low altitude coastal and sub-coastal areas and extend inland for distance more than 100 km along river valleys and across watersheds, they are to be found on the coasts of East Sumatra, West Papua, Papua New Guinea, Peninsular Malaya, Sarawak, Southeast Thailand, the Philippines. Indonesia has the largest area of tropical peatland. Of the total 440,000 km2 tropical peat swamp, about 210,000 km2 are located in Indonesia.
The Vasyugan Swamp is a large swamp in the western Siberia area of the Russian Federation. This is one of the largest swamps in the world; the Atchafalaya Swamp at the lower end of the Mississippi River is the largest swamp in the United States. It is an important example of southern cypress swamp but it has been altered by logging and levee construction. Other famous swamps in the United States are the forested portions of the Everglades, Okefenokee Swamp, Barley Barber Swamp, Great Cypress Swamp and the Great Dismal Swamp; the Okefenokee is located in extreme southeastern Georgia and extends into northeastern Florida. The Great Cypress Swamp is in Delaware but extends into Maryland on the Delmarva Peninsula. Point Lookout State Park on the southern tip of Maryland contains a large amount of swamps and marshes; the Great Dismal Swamp lies in extreme southeastern Virginia and extreme northeastern North Carolina. Both are National Wildlife Refuges. Another swamp area, Reelfoot Lake of extreme western Tennessee and Kentucky, was created by the 1811–12 New Madrid earthquakes.
Caddo Lake, the Great Dismal and Reelfoot are swamps. Swamps are called bayous in the southeastern United States in the Gulf Coast region; the worl
Freshwater, Isle of Wight
Freshwater is a large village and civil parish at the western end of the Isle of Wight, England. Freshwater Bay is a small cove on the south coast of the Island which gives its name to the nearby part of Freshwater. Freshwater sits at the western end of the region known as the Back of the Wight or the West Wight, a popular tourist area. Freshwater is close to steep chalk cliffs, it was the birthplace of physicist Robert Hooke and was the home of Poet Laureate Alfred Lord Tennyson. Freshwater is famous for its geology and coastal rock formations that have resulted from centuries worth of coastal erosion; the "Arch Rock" was a well-known local landmark that collapsed on 25 October 1992. The neighbouring "Stag Rock" is so named because a stag leaped to the rock from the cliff to escape during a hunt. Another huge slab fell off the cliff face in 1968, is now known as the "Mermaid Rock". Behind Mermaid Rock lies a small Sea cave that cuts several metres into the new cliff. Freshwater's beach is popular.
It is sandy but it is covered in chalk from the nearby cliffs, gathered by tourists as souvenirs. Freshwater features an excellent example of The Albion; the Albion was built around the time Freshwater became popularised as a coastal resort, is still popular today. However, heavy storms which lift rocks and other debris from the beach means that the building's exterior walls have to be repainted, with cracks and dents in the walls being repaired too; the hills above Freshwater are named after Tennyson. On the nearby Tennyson Down is a Cornish granite cross erected in 1897 in tribute to Tennyson, "by the people of Freshwater, other friends in England and America." There is a hill in the area called'Hooke Hill', named for Robert Hooke. All Saints' Church, Freshwater is one of the oldest churches on the Isle of Wight, was listed in the Domesday survey of 1086. Mark Whatson is the pastor of All Saints, an Anglican church in the Anglican Diocese of Portsmouth. A primary school associated with the church is nearby.
There is a marble memorial commemorating Tennyson in All Saints Church. Tennyson's wife Emily and other family members are buried in the church cemetery; the church is the site of a memorial to Tennyson's son, Lionel Tennyson, who died of malaria in 1886. Dimbola Lodge, the home of Julia Margaret Cameron and now a photographic museum, is in the village of Freshwater Bay, part of Freshwater. There is a tearoom and bookstore. Tennyson's son, Hallam donated land for a new church in Freshwater Bay. Hallam's wife Audrey suggested. St. Agnes' Church, Freshwater was consecrated on 12 August 1908, it is the only thatched church on the Isle of Wight. Freshwater was the site of the largest station on the Freshwater and Newport Railway that operated from 20 July 1889 to 21 September 1953; the station location is now occupied by a garden centre. Freshwater is near the source of the Western Yar. Freshwater Marshes are a Site of Special Scientific Interest, a large part of the Marshes are a Local Nature Reserve called Afton Marshes.
At the western end of Freshwater Bay on a bluff are the remains of Fort Redoubt known as Fort Freshwater or Freshwater Redoubt, a Palmerston Fort. Fort Redoubt was built in 1855-1856 to protect Freshwater Bay, was in use until the early 20th century, it was sold by the military in 1928. Presently, part of it is a private residence, other portions are being developed as holiday flats. A doorway carved into the cliff below the fort was the main access to the building from the beach, although most of the iron stairway that gave access has broken up due to the repeated actions of rust and the tide. Two unusual structures that have been described as ice houses, pottery kilns or crematoria are found on Moons Hill in Freshwater. Robert Walker was the first to excavate these features in the 1890s, he thought they were evidence of a Phoenician settlement in Freshwater. Chemical analyses suggest that they were most lime kilns; the renowned scientist Robert Hooke was born in Freshwater in 1635. His father John Hooke was the curate of All Saints Church in Freshwater.
When Hooke's father died in 1648, Hooke left Freshwater for London to be apprenticed to portrait painter Peter Lely. After that, he went to Westminster School and Oxford. Painter George Morland lived in Freshwater in a structure known as the "Cabin" around 1800. British Poet laureate Alfred Lord Tennyson lived at nearby Farringford House. Tennyson lived at Farringford from 1853 until the end of his life in 1892. Tennyson wrote of Farringford: “Where, far from noise and smoke of townI watch the twilight falling brown,All round a careless-ordered garden,Close to the ridge of a noble down.” Tennyson rented Farringford in 1853, bought it in 1856. He found that there were too many starstruck tourists who pestered him in Farringford, so he moved to "Aldworth", a stately home on a hill known as Blackdown between Lurgashall and Fernhurst, about 2 km south of Haslemere in West Sussex in 1869. However, he returned to Farringford to spend the winters. Pioneering photographer Julia Margaret Cameron lived in Freshwater at Dimbola Lodge from 1860 to 1875.
In 1960, Dekyi Tseri, mother of the current Dalai Lama, stayed at the guest house of Sir Basil Gould's widow Cecily in Freshwater for six weeks. Tseri, known to Tibetans as "Amala", meaning "The Great Mother", was recuperating after a throat operation to remove a benign polyp performed at St. Mary's Hospital in London. Freshwater was the birthplace of Sir Vivian Ernest Fuchs FRS (1
Mantellisaurus is a genus of iguanodontian dinosaur that lived in the Barremian and early Aptian ages of the Early Cretaceous Period of Europe. Its remains are known from Belgium and Germany; the type and only species is M. atherfieldensis. Known as Iguanodon atherfieldensis, the new genus Mantellisaurus was erected for the species by Gregory Paul in 2007. According to Paul, Mantellisaurus was more built than Iguanodon and more related to Ouranosaurus, making Iguanodon in its traditional sense paraphyletic, it is known from many complete and complete skeletons. The genus name honours the discoverer of Iguanodon. Mantellisaurus was a constructed iguanodont. Compared to Iguanodon bernissartensis, Mantellisaurus was smaller, estimated at 750 kilograms in weight, its forelimbs were proportionally shorter than those of I. bernissartensis. In Mantellisaurus the forelimbs were about half the length of the hindlimbs whereas they were about 70 percent the length of the hindlimbs in I. bernissartensis. Due to the short length of its forelimbs and the shortness of its body, Paul proposed that it was bipedal, only going on all fours when standing still or moving slowly.
The holotype fossil, NHMUK R5764, was discovered by Reginald Walter Hooley in 1914 in the upper Vectis Formation of southern England and reported upon in 1917. He posthumously named it Iguanodon atherfieldensis in 1925. Atherfield is the name of a village on the southwest shore of the Isle of Wight where the fossil was found. Synonyms include Dollodon and Proplanicoxa. Specimen IRSNB 1551 from the Sainte-Barbe Clays, became the second mounted skeleton of a non-avian dinosaur made out of actual bone when put on display by Louis Dollo in 1884; this specimen was assigned to Iguanodon mantelli by George Albert Boulenger in 1881, but was in 1986 thought to pertain to Iguanodon atherfieldensis by David Bruce Norman. The specimen was assigned to its own genus and species, Dollodon bampingi, by Gregory S. Paul in 2008; the genus was named after Dollo, who first described the remains, the specific name was in honour of popular science writer Daniel Bamping, who assisted Paul in his investigations. Paul noted several differences between the Mantellisaurus type and IRSNB 1551.
The Mantellisaurus type had proportionally shorter forelimbs with a larger pelvis and he argued it was more bipedal, whereas IRSNB 1551 was more to be quadrupedal. Paul noted that the snout and trunk of IRSNB 1551 were proportionally longer than the Mantellisaurus type specimen; the validity of Dollodon has since been disputed. In 2010, Kenneth Carpenter and Yusuke Ishida synonymized Dollodon bampingi with Iguanodon seelyi, a species based on BMNH R 28685 from Wessex Formation, England. David B. Norman and Andrew McDonald do not consider Dollodon a valid genus or species and instead include it with Mantellisaurus; the cladogram below follows an analysis by Andrew McDonald, 2012. Cornuel, M. 1850, Note sur des ossements fossiles decouvertes dans le calcaire neocomien de Wassy: Bulletin de la societie geologiques de France, 2nd series, v. 7, p. 702-704. Hooley, W. 1925, On the skeleton of Iguanodon atherfieldensis sp. nov. from the Wealden Shales of Atherfield: Quarterly Journal of the Geological Society of London, v. 81, p. 1-61.
Hulke, J. W. 1879, Vectisaurus valdensis, a new Wealden Dinosaur: Quarterly Journal of the Geological Society of London, v. 35, p. 421-424. Owen, R. 1842, Report on British Fossil Reptiles. Part II: Report of the British Association for the Advancement of Science, v. 11, p. 60-204. Lydekker, R. 1888, Catalogue of the Fossil Reptilia and Amphibia in the British Museum, Cromwell Road, S. W. Part 1. Containing the Orders Ornithosauria, Dinosauria, Squamta and Proterosauria: British Museum of Natural History, London, 309pp. Norman, D. B. 2012. "Iguanodontian Taxa from the Lower Cretaceous of England and Belgium". In: Pascal Godefroit, Bernissart Dinosaurs and Early Cretaceous Terrestrial Ecosystems. Indiana University Press. 464 pp. http://www.iupress.indiana.edu/product_info.php?products_id=800408 Paul, G. S. 2007. Turning the old into the new: a separate genus for the gracile iguanodont from the Wealden of England. Indiana University Press, Bloomington
Sauropodomorpha is an extinct clade of long-necked, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods grew to large sizes, had long necks and tails, were quadrupedal, became the largest animals to walk the Earth; the "prosauropods", which preceded the sauropods, were smaller and were able to walk on two legs. The sauropodomorphs were the dominant terrestrial herbivores throughout much of the Mesozoic Era, from their origins in the mid-Triassic until their decline and extinction at the end of the Cretaceous. Sauropodomorphs were adapted to browsing higher than any other contemporary herbivore, giving them access to high tree foliage; this feeding strategy is supported by many of their defining characteristics, such as: a light, tiny skull on the end of a long neck and a counterbalancing long tail. Their teeth were weak, shaped like leaves or spoons. Instead of grinding teeth, they had stomach stones, similar to the gizzard stones of modern birds and crocodiles, to help digest tough plant fibers.
The front of the upper mouth bends down in. One of the earliest known sauropodomorphs, was small and slender; the largest sauropods, like Supersaurus, Diplodocus hallorum and Argentinosaurus, reached 30–40 metres in length, 60,000–100,000 kilograms or more in mass. Bipedal, as their size increased they evolved a four-legged graviportal gait adapted only to walking on land, like elephants; the early sauropodomorphs were most omnivores as their shared common ancestor with the other saurischian lineage was a carnivore. Therefore, their evolution to herbivory went hand in hand with their increasing size and neck length, they had large nostrils, retained a thumb with a big claw, which may have been used for defense — though their primary defensive adaptation was their extreme size. Sauropodomorphs can be distinguished as a group on the basis of some of the following synapomorphies: The presence of large nares; the distal part of the tibia is covered by an ascending process of the astragalus. Their hind limbs are short.
The presence of three or more sacral vertebrae. The teeth are thin and are spatula-like, with bladed and serrated crowns; the presence of a minimum of 10 cervical vertebrae that are elongated The presence of 25 presacral vertebrae The manus had a large digit I Among the first dinosaurs to evolve in the Late Triassic Period, about 230 million years ago, they became the dominant herbivores by halfway through the late Triassic. Their perceived decline in the early Cretaceous is most a bias in fossil sampling, as most fossils are known from Europe and North America. Sauropods were still the dominant herbivores in the Gondwanan landmasses, however; the spread of flowering plants and "advanced" ornithischians, another major group of herbivorous dinosaurs, are most not a major factor in sauropod decline in the northern continents. Like all non-avian dinosaurs, the sauropodomorphs became extinct 66 Mya, during the Cretaceous–Paleogene extinction event; the earliest and most basal sauropodomorphs known are Chromogisaurus novasi and Panphagia protos, both from the Ischigualasto Formation, dated to 231.4 million years ago.
Some studies have found Eoraptor lunensis, traditionally considered a theropod, to be an early member of the sauropodomorph lineage, which would make it the most basal sauropodomorph known. Sauropodomorpha is one of the two major clades within the order Saurischia; the sauropodomorphs' sister group, the Theropoda, includes bipedal carnivores like Velociraptor and Tyrannosaurus. However, sauropodomorphs share a number of characteristics with the Ornithischia, so a small minority of palaeontologists, like Bakker, have placed both sets of herbivores within a group called "Phytodinosauria" or "Ornithischiformes". In Linnaean taxonomy, Sauropodomorpha is left unranked, it was established by Friedrich von Huene in 1932, who broke it into two groups: the basal forms within Prosauropoda, their descendants, the giant Sauropoda. Phylogenetic analyses by Adam Yates and others placed Sauropoda within a paraphyletic "Prosauropoda". Recent cladistic analyses suggest that the clade Prosauropoda, named by Huene in 1920 and was defined by Sereno, in 1998, as all animals more related to Plateosaurus engelhardti than to Saltasaurus loricatus, is a junior synonym of Plateosauridae as both contain the same taxa.
Most modern classification schemes break the prosauropods into a half-dozen groups that evolved separately from one common lineage. While they have a number of shared characteristics, the evolutionary requirements for giraffe-like browsing high in the trees may have caused convergent evolution, where similar traits evolve separately because they faced the same evolutionary pressure, instead of trait
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago, although the exact origin and timing of the evolution of dinosaurs is the subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201 million years ago. Reverse genetic engineering and the fossil record both demonstrate that birds are modern feathered dinosaurs, having evolved from earlier theropods during the late Jurassic Period; as such, birds were the only dinosaur lineage to survive the Cretaceous–Paleogene extinction event 66 million years ago. Dinosaurs can therefore be divided into birds; this article deals with non-avian dinosaurs. Dinosaurs are a varied group of animals from taxonomic and ecological standpoints. Birds, at over 10,000 living species, are the most diverse group of vertebrates besides perciform fish. Using fossil evidence, paleontologists have identified over 500 distinct genera and more than 1,000 different species of non-avian dinosaurs.
Dinosaurs are represented on every continent by fossil remains. Through the first half of the 20th century, before birds were recognized to be dinosaurs, most of the scientific community believed dinosaurs to have been sluggish and cold-blooded. Most research conducted since the 1970s, has indicated that all dinosaurs were active animals with elevated metabolisms and numerous adaptations for social interaction; some were herbivorous, others carnivorous. Evidence suggests that egg-laying and nest-building are additional traits shared by all dinosaurs and non-avian alike. While dinosaurs were ancestrally bipedal, many extinct groups included quadrupedal species, some were able to shift between these stances. Elaborate display structures such as horns or crests are common to all dinosaur groups, some extinct groups developed skeletal modifications such as bony armor and spines. While the dinosaurs' modern-day surviving avian lineage are small due to the constraints of flight, many prehistoric dinosaurs were large-bodied—the largest sauropod dinosaurs are estimated to have reached lengths of 39.7 meters and heights of 18 meters and were the largest land animals of all time.
Still, the idea that non-avian dinosaurs were uniformly gigantic is a misconception based in part on preservation bias, as large, sturdy bones are more to last until they are fossilized. Many dinosaurs were quite small: Xixianykus, for example, was only about 50 cm long. Since the first dinosaur fossils were recognized in the early 19th century, mounted fossil dinosaur skeletons have been major attractions at museums around the world, dinosaurs have become an enduring part of world culture; the large sizes of some dinosaur groups, as well as their monstrous and fantastic nature, have ensured dinosaurs' regular appearance in best-selling books and films, such as Jurassic Park. Persistent public enthusiasm for the animals has resulted in significant funding for dinosaur science, new discoveries are covered by the media; the taxon'Dinosauria' was formally named in 1841 by paleontologist Sir Richard Owen, who used it to refer to the "distinct tribe or sub-order of Saurian Reptiles" that were being recognized in England and around the world.
The term is derived from Ancient Greek δεινός, meaning'terrible, potent or fearfully great', σαῦρος, meaning'lizard or reptile'. Though the taxonomic name has been interpreted as a reference to dinosaurs' teeth and other fearsome characteristics, Owen intended it to evoke their size and majesty. Other prehistoric animals, including pterosaurs, ichthyosaurs and Dimetrodon, while popularly conceived of as dinosaurs, are not taxonomically classified as dinosaurs. Pterosaurs are distantly related to dinosaurs; the other groups mentioned are, like dinosaurs and pterosaurs, members of Sauropsida, except Dimetrodon. Under phylogenetic nomenclature, dinosaurs are defined as the group consisting of the most recent common ancestor of Triceratops and Neornithes, all its descendants, it has been suggested that Dinosauria be defined with respect to the MRCA of Megalosaurus and Iguanodon, because these were two of the three genera cited by Richard Owen when he recognized the Dinosauria. Both definitions result in the same set of animals being defined as dinosaurs: "Dinosauria = Ornithischia + Saurischia", encompassing ankylosaurians, ceratopsians, ornithopods and sauropodomorphs.
Birds are now recognized as being the sole surviving lineage of theropod dinosaurs. In traditional taxonomy, birds were considered a separate class that had evolved from dinosaurs, a distinct superorder. However, a majority of contemporary paleontologists concerned with dinosaurs reject the traditional style of classification in favor of phylogenetic taxonomy. Birds are thus considered to be dinosaurs and dinosaurs are, not extinct. Birds are classified as belonging to the subgroup M
Turtles are diapsids of the order Testudines characterized by a special bony or cartilaginous shell developed from their ribs and acting as a shield. "Turtle" may refer to fresh-water and sea-dwelling testudines. The order Testudines includes both extinct species; the earliest known members of this group date from 220 million years ago, making turtles one of the oldest reptile groups and a more ancient group than snakes or crocodilians. Of the 356 known species alive today, some are endangered. Turtles are ectotherms—animals called cold-blooded—meaning that their internal temperature varies according to the ambient environment. However, because of their high metabolic rate, leatherback sea turtles have a body temperature, noticeably higher than that of the surrounding water. Turtles are classified as amniotes, along with other reptiles and mammals. Like other amniotes, turtles breathe air and do not lay eggs underwater, although many species live in or around water; the study of turtles is called cheloniology, after the Greek word for turtle.
It is sometimes called testudinology, after the Latin name for turtles. Differences exist in usage of the common terms turtle and terrapin, depending on the variety of English being used; these terms do not reflect precise biological or taxonomic distinctions. Turtle may either refer to the order as a whole, or to particular turtles that make up a form taxon, not monophyletic, or may be limited to only aquatic species. Tortoise refers to any land-dwelling, non-swimming chelonian. Terrapin is used to describe several species of small, hard-shell turtles those found in brackish waters. In North America, all chelonians are called turtles. Tortoise is used only in reference to terrestrial turtles or, more narrowly, only those members of Testudinidae, the family of modern land tortoises. Terrapin may refer to small semi-aquatic turtles that live in fresh and brackish water, in particular the diamondback terrapin. Although the members of the genus Terrapene dwell on land, they are referred to as box turtles rather than tortoises.
The American Society of Ichthyologists and Herpetologists uses "turtle" to describe all species of the order Testudines, regardless of whether they are land-dwelling or sea-dwelling, uses "tortoise" as a more specific term for slow-moving terrestrial species. In the United Kingdom, the word turtle is used for water-dwelling species, including ones known in the US as terrapins, but not for terrestrial species, which are known only as tortoises; the word chelonian is popular among veterinarians and conservationists working with these animals as a catch-all name for any member of the superorder Chelonia, which includes all turtles living and extinct, as well as their immediate ancestors. Chelonia is based on the Greek word for χελώνη chelone. Testudines, on the other hand, is based on the Latin word for testudo. Terrapin comes from an Algonquian word for turtle; some languages do not have this distinction. For example, in Spanish, the word tortuga is used for turtles and terrapins. A sea-dwelling turtle is tortuga marina, a freshwater species tortuga de río, a tortoise tortuga terrestre.
The largest living chelonian is the leatherback sea turtle, which reaches a shell length of 200 cm and can reach a weight of over 900 kg. Freshwater turtles are smaller, but with the largest species, the Asian softshell turtle Pelochelys cantorii, a few individuals have been reported up to 200 cm; this dwarfs the better-known alligator snapping turtle, the largest chelonian in North America, which attains a shell length of up to 80 cm and weighs as much as 113.4 kg. Giant tortoises of the genera Geochelone and others were widely distributed around the world into prehistoric times, are known to have existed in North and South America and Africa, they became extinct at the same time as the appearance of man, it is assumed humans hunted them for food. The only surviving giant tortoises are on the Seychelles and Galápagos Islands and can grow to over 130 cm in length, weigh about 300 kg; the largest chelonian was Archelon ischyros, a Late Cretaceous sea turtle known to have been up to 4.6 m long.
The smallest turtle is the speckled padloper tortoise of South Africa. It weighs about 140 g. Two other species of small turtles are the American mud turtles and musk turtles that live in an area that ranges from Canada to South America; the shell length of many species in this group is less than 13 cm in length. Turtles are divided according to how they retract their necks into their shells; the mechanism of neck retraction differs phylogenetically: the suborder Pleurodira retracts laterally to the side, anterior to shoulder girdles, while the suborder Cryptodira retracts straight back, between shoulder girdles. These motions are due to the morphology and arrangement of cervical vertebrae. Of all recent turtles, the cervical column consists of nine joints and eight vertebrae, which are individually independent. Since these vertebrae are not fused and are rounded, the neck is more flexible, being able to bend in the backwards and sideways directions; the primary function and evolutionary implicastion of neck retraction is thought to