Mollusca is the second largest phylum of invertebrate animals. The members are known as mollusks. Around 85,000 extant species of molluscs are recognized; the number of fossil species is estimated between 100,000 additional species. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs live in freshwater and terrestrial habitats, they are diverse, not just in size and in anatomical structure, but in behaviour and in habitat. The phylum is divided into 8 or 9 taxonomic classes, of which two are extinct. Cephalopod molluscs, such as squid and octopus, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species; the gastropods are by far the most numerous molluscs and account for 80% of the total classified species. The three most universal features defining modern molluscs are a mantle with a significant cavity used for breathing and excretion, the presence of a radula, the structure of the nervous system.
Other than these common elements, molluscs express great morphological diversity, so many textbooks base their descriptions on a "hypothetical ancestral mollusc". This has a single, "limpet-like" shell on top, made of proteins and chitin reinforced with calcium carbonate, is secreted by a mantle covering the whole upper surface; the underside of the animal consists of a single muscular "foot". Although molluscs are coelomates, the coelom tends to be small; the main body cavity is a hemocoel. The "generalized" mollusc's feeding system consists of a rasping "tongue", the radula, a complex digestive system in which exuded mucus and microscopic, muscle-powered "hairs" called cilia play various important roles; the generalized mollusc has three in bivalves. The brain, in species that have one, encircles the esophagus. Most molluscs have eyes, all have sensors to detect chemicals and touch; the simplest type of molluscan reproductive system relies on external fertilization, but more complex variations occur.
All produce eggs, from which may emerge trochophore larvae, more complex veliger larvae, or miniature adults. The coelomic cavity is reduced, they have kidney-like organs for excretion. Good evidence exists for the appearance of gastropods and bivalves in the Cambrian period, 541 to 485.4 million years ago. However, the evolutionary history both of molluscs' emergence from the ancestral Lophotrochozoa and of their diversification into the well-known living and fossil forms are still subjects of vigorous debate among scientists. Molluscs still are an important food source for anatomically modern humans. There is a risk of food poisoning from toxins which can accumulate in certain molluscs under specific conditions and because of this, many countries have regulations to reduce this risk. Molluscs have, for centuries been the source of important luxury goods, notably pearls, mother of pearl, Tyrian purple dye, sea silk, their shells have been used as money in some preindustrial societies. Mollusc species can represent hazards or pests for human activities.
The bite of the blue-ringed octopus is fatal, that of Octopus apollyon causes inflammation that can last for over a month. Stings from a few species of large tropical cone shells can kill, but their sophisticated, though produced, venoms have become important tools in neurological research. Schistosomiasis is transmitted to humans via water snail hosts, affects about 200 million people. Snails and slugs can be serious agricultural pests, accidental or deliberate introduction of some snail species into new environments has damaged some ecosystems; the words mollusc and mollusk are both derived from the French mollusque, which originated from the Latin molluscus, from mollis, soft. Molluscus was itself an adaptation of Aristotle's τὰ μαλάκια ta malákia, which he applied inter alia to cuttlefish; the scientific study of molluscs is accordingly called malacology. The name Molluscoida was used to denote a division of the animal kingdom containing the brachiopods and tunicates, the members of the three groups having been supposed to somewhat resemble the molluscs.
As it is now known these groups have no relation to molluscs, little to one another, the name Molluscoida has been abandoned. The most universal features of the body structure of molluscs are a mantle with a significant cavity used for breathing and excretion, the organization of the nervous system. Many have a calcareous shell. Molluscs have developed such a varied range of body structures, it is difficult to find synapomorphies to apply to all modern groups; the most general characteristic of molluscs is they are bilaterally symmetrical. The following are present in all modern molluscs: The dorsal part of the body wall is a mantle which secretes calcareous spicules, plates or shells, it overlaps the body with enough spare room to form a mantle cavity. The anus and genitals open into the mantle cavity. There are two pairs of main nerve cords. Other characteristics that appear in textbooks have significant exceptions: Estimates of accepted described living species of molluscs vary from 50,000 to a maximum of 120,000 species.
In 1969 David Nicol estimated the probable total number of living mollusc species at 107,000 of which were ab
Isle of Portland
The Isle of Portland is a limestone tied island, 4 miles long by 1.7 miles wide, in the English Channel. Portland is 5 miles south of the resort of Weymouth, forming the southernmost point of the county of Dorset, England. A barrier beach called; the A354 road passes down the Portland end of the beach and over the Fleet Lagoon by bridge to the mainland. Portland and Weymouth together form the borough of Portland; the population of Portland is 12,400. Portland is a central part of the Jurassic Coast, a World Heritage Site on the Dorset and east Devon coast, important for its geology and landforms. Portland stone, famous for its use in British and world architecture, including St Paul's Cathedral and the United Nations Headquarters, continues to be quarried. Portland Harbour, in between Portland and Weymouth, is one of the largest man-made harbours in the world; the harbour was made by the building of stone breakwaters between 1848 and 1905. From its inception it was a Royal Navy base, played prominent roles during the First and Second World Wars.
The harbour is now a civilian port and popular recreation area, was used for the 2012 Olympic Games. The name Portland is used for one of the British Sea Areas, has been exported as the name of North American and Australian towns. Portland has been inhabited since at least the Mesolithic period —there is archaeological evidence of Mesolithic inhabitants at the Culverwell Mesolithic Site, near Portland Bill, of habitation since then; the Romans occupied Portland. Although the beginning of the Viking Age in England is dated to their raid in 793, when they destroyed the abbey on Lindisfarne, their first documented landing occurred in Portland four years earlier, in 789, as recorded in the Anglo-Saxon Chronicle. Three lost Viking ships from Hordaland landed at Portland Bill; the king's reeve tried to collect taxes from them. In 1539 King Henry VIII ordered the construction of Portland Castle for defence against attacks by the French, it is one of the best preserved castles from this period, is opened to the public by the custodians English Heritage.
In the 17th century, chief architect and Surveyor-General to James I, Inigo Jones, surveyed the area and introduced the local Portland stone to London, using it in his Banqueting House and for repairs on St Paul's Cathedral. His successor, Sir Christopher Wren, the architect and Member of Parliament for nearby Weymouth, used six million tons of white Portland limestone to rebuild destroyed parts of the capital after the Great Fire of London of 1666. Well-known buildings in the capital, including St Paul's Cathedral and the eastern front of Buckingham Palace feature the stone. After the First World War, a quarry was opened by The Crown Estate to provide stone for the Cenotaph in Whitehall and half a million gravestones for war cemeteries, after the Second World War hundreds of thousands of gravestones were hewn for soldiers who had fallen on the Western Front. Portland cement has nothing to do with Portland. There have been railways in Portland since the early 19th century; the Merchant's Railway was the earliest—it opened in 1826 and ran from the quarries at the north of Tophill to a pier at Castletown, from where the Portland stone was shipped around the country.
The Weymouth and Portland Railway was laid in 1865, ran from a station in Melcombe Regis, across the Fleet and along the low isthmus behind Chesil Beach to a station at Victoria Square in Chiswell. At the end of the 19th century the line was extended to the top of the island as the Easton and Church Ope Railway, running through Castletown and ascending the cliffs at East Weares, to loop back north to a station in Easton; the line closed to passengers in 1952, the final goods train ran in April 1965. The Royal National Institution for the Preservation of Life from Shipwreck stationed a lifeboat at Portland in 1826, withdrawn in 1851. Coastal flooding has affected Portland's residents and transport for centuries—the only way off the island by land is along the causeway in the lee of Chesil Beach. At times of extreme floods this road link is cut by floods; the low-lying village of Chiswell used to flood on average every 5 years. Chesil Beach faces severe storms and massive waves, which have a fetch across the Atlantic Ocean.
Following two severe flood events in the 1970s, Weymouth and Portland Borough Council and Wessex Water decided to investigate the structure of the beach, coastal management schemes that could be built to protect Chiswell and the beach road. In the 1980s it was agreed that a scheme to protect against a one-in-five-year storm would be practicable. Hard engineering techniques were employed in the scheme, including a gabion running 550 metres to the north of Chiswell, an extended sea wall in Chesil Cove, a culvert running from inside the beach, underneath the beach road and into Portland Harbour, to divert flood water away from low-lying areas. At the start of the First World War, HMS Hood was sunk in the passage between the southern breakwaters to protect the harbour from torpedo and submarine attack. Portland Harbour was formed by the construction of breakwaters, but before that the natural anchorage had hosted ships of the Royal Navy for more than 50
Dorset is a county in South West England on the English Channel coast. The ceremonial county comprises the unitary authority areas of Bournemouth and Poole and Dorset. Covering an area of 2,653 square kilometres, Dorset borders Devon to the west, Somerset to the north-west, Wiltshire to the north-east, Hampshire to the east; the county town is Dorchester, in the south. After the reorganisation of local government in 1974 the county's border was extended eastward to incorporate the Hampshire towns of Bournemouth and Christchurch. Around half of the population lives in the South East Dorset conurbation, while the rest of the county is rural with a low population density; the county has a long history of human settlement stretching back to the Neolithic era. The Romans conquered Dorset's indigenous Celtic tribe, during the early Middle Ages, the Saxons settled the area and made Dorset a shire in the 7th century; the first recorded Viking raid on the British Isles occurred in Dorset during the eighth century, the Black Death entered England at Melcombe Regis in 1348.
Dorset has seen much civil unrest: in the English Civil War, an uprising of vigilantes was crushed by Oliver Cromwell's forces in a pitched battle near Shaftesbury. During the Second World War, Dorset was involved in the preparations for the invasion of Normandy, the large harbours of Portland and Poole were two of the main embarkation points; the former was the sailing venue in the 2012 Summer Olympics, both have clubs or hire venues for sailing, Cornish pilot gig rowing, sea kayaking and powerboating. Dorset has a varied landscape featuring broad elevated chalk downs, steep limestone ridges and low-lying clay valleys. Over half the county is designated as an Area of Outstanding Natural Beauty. Three-quarters of its coastline is part of the Jurassic Coast Natural World Heritage Site due to its geological and palaeontologic significance, it features notable landforms such as Lulworth Cove, the Isle of Portland, Chesil Beach and Durdle Door. Agriculture was traditionally the major industry of Dorset but is now in decline and tourism has become important to the economy.
There are no motorways in Dorset but a network of A roads cross the county and two railway main lines connect to London. Dorset has ports at Poole and Portland, an international airport; the county has a variety of museums and festivals, is host to the Great Dorset Steam Fair, one of the biggest events of its kind in Europe. It is the birthplace of Thomas Hardy, who used the county as the principal setting of his novels, William Barnes, whose poetry celebrates the ancient Dorset dialect. Dorset derives its name from the county town of Dorchester; the Romans established the settlement in the 1st century and named it Durnovaria, a Latinised version of a Common Brittonic word meaning "place with fist-sized pebbles". The Saxons named the town Dornwaraceaster and Dornsæte came into use as the name for the inhabitants of the area from "Dorn"—a reduced form of Dornwaraceaster—and the Old English word "sæte" meaning people, it is first mentioned in the Anglo-Saxon Chronicle in AD 845 and in the 10th century the county's archaic name, "Dorseteschyre", was first recorded.
The first human visitors to Dorset were Mesolithic hunters, from around 8000 BC. The first permanent Neolithic settlers appeared around 3000 BC and were responsible for the creation of the Dorset Cursus, a 10.5-kilometre monument for ritual or ceremonial purposes. From 2800 BC onwards Bronze Age farmers cleared Dorset's woodlands for agricultural use and Dorset's high chalk hills provided a location for numerous round barrows. During the Iron Age, the British tribe known as the Durotriges established a series of hill forts across the county—most notably Maiden Castle, one of the largest in Europe; the Romans arrived in Dorset during their conquest of Britain in AD 43. Maiden Castle was captured by a Roman legion under the command of Vespasian, the Roman settlement of Durnovaria was established nearby. Bokerley Dyke, a large defensive ditch built by the county's post-Roman inhabitants near the border with modern-day Hampshire, delayed the advance of the Saxons into Dorset for 150 years. However, by the end of the 7th century Dorset had fallen under Saxon control and been incorporated into the Kingdom of Wessex.
The Saxons established a diocese at Sherborne and Dorset was made a shire—an administrative district of Wessex and predecessor to the English county system—with borders that have changed little since. In 789 the first recorded Viking attack on the British Isles took place in Dorset on the Portland coast, they continued to raid into the county for the next two centuries. After the Norman Conquest in 1066, feudal rule was established in Dorset and the bulk of the land was divided between the Crown and ecclesiastical institutions; the Normans consolidated their control over the area by constructing castles at Corfe and Dorchester in the early part of the 12th century. Over the next 200 years Dorset's population grew and additional land was enclosed for farming to provide the extra food required; the wool trade, the quarrying of Purbeck Marble and the busy ports of Weymouth, Melcombe Regis, Lyme Regis and Bridport brought prosperity to the county. However, Dorset was devastated by the bubonic plague in 1348 which arrived in Melcombe Regis on a ship from Gascony.
The disease, more known as the Black Death, created an epidemic that spread a
Chesil Beach, sometimes called Chesil Bank, in Dorset, southern England is one of three major shingle structures in Britain. Its name is derived from the Old English ceosel or cisel, meaning "gravel" or "shingle"; the beach is identified as a tombolo, although research into the geomorphology of the area has revealed that it is in fact a barrier beach which has "rolled" landwards, joining the mainland with the Isle of Portland and giving the appearance of a tombolo. The shingle beach is 200 metres wide and 15 metres high; the beach and The Fleet, a shallow tidal lagoon, are part of the Jurassic Coast and a UNESCO World Heritage Site. The beach curves at the eastern end, near the village of Chiswell, forms Chesil Cove against the cliffs of the Isle of Portland, this protects the low-lying village from flooding, it was named "Dead Man's Bay" by Thomas Hardy. Westwards the shingle forms a straight line along the coast; the beach provides shelter from the prevailing winds and waves for the town of Weymouth and the village of Chiswell on Portland.
Simon Jenkins rates the view of Chesil Beach from Abbotsbury along the coast to Portland Bill as one of the top ten in England. The origin of Chesil Beach has been argued over for some time, it was believed that beach material was from the Budleigh Salterton pebble beds to the west and from Portland to the south east. The differences between the pebbles on the beach and nearby sources is now put down to the Flandrian isostatic sea level rise, so the feature could be considered a barrier beach or bar, that happens to connect the mainland to an island rather than a'true' tombolo. Tombolos are created due to the effects of the island on waves and to sediment transport, which produces a beach perpendicular to the mainland rather than parallel to it. Fossils occur all along the landward shore of the Fleet and along the landward side of Chesil Beach from Abbotsbury to West Bay; the main site is at Burton Bradstock. There have been many shipwrecks on Chesil Beach during the age of sail; the beach was dangerous within the English Channel, as it forms an extended lee shore during south-westerly gales.
A ship coming up the Channel had to clear Portland Bill to be safe, but the wind and tide would be pushing it northwards into Lyme Bay. When sailing ships were common, a strong string of coastguards were based along the beach, with lookouts and cottages at Chiswell, Wyke Regis, Langton Herring, East Bexington, Burton Bradstock and West Bay. At present there are no manned stations along the beach, as coverage is provided when required from Portland Coastguard; the local fishermen at Portland, developed a purpose-built vessel to withstand the sea actions of Chesil Beach. The boat, known as a Lerret, is a double-ended open fishing boat — 16–17 ft long — used for seine net fishing, it is rowed by four people with a fifth to steer and deploy the net. Much of the villages Fleet and Chiswell were destroyed in the Great Storm of 1824. Over the centuries Chiswell had battled with the sea and was flooded during rough winter storms. In the storms the sea would pour through the upper part of the bank, for this reason plans to drain the Fleet were abandoned in 1630.
The great storm of November 1824 struck the village with disastrous results - an event from which Chiswell would never recover. Since various defences have been set-up to aid the village, notably the sea wall and promenade which commenced work in 1958, was completed in 1965; the Weymouth to Portland Railway line was opened in 1865, built along the southern end of the beach. It closed to passengers in 1952 and closed to all traffic in 1965; the line included a viaduct across Ferry Bridge. Over the last 150 years there have been a number of proposals to build a line from Weymouth to Bridport running the length of Chesil Beach. A line could not be continued through lack of money. A line was built from Maiden Newton to Bridport and onwards to West Bay. A more recent proposal was to build a light railway between West Bay. A rifle range, built around 1907, is situated near Ferry Bridge, it had 100 yard increments up to 800 yards, some remains of this structure can still be seen today. The Royal Navy operated a minesweeping trials range off West Bexington for many years following World War II.
It was abandoned in the mid-1980s. The cables came ashore under the beach at the West Bexington car park, today the range control building can still be seen behind the car park, while one of the theodolite stations is located near the entrance to the Cogden Beach car park. From West Bay to Cliff End the beach is piled up against the cliff. At Cliff End a hollow forms behind the beach and at Abbotsbury a stretch of saline water called the Fleet Lagoon begins; the Fleet is home to many wading birds and Abbotsbury Swannery, fossils can be found in the sand and mud. The Fleet connects to Portland Harbour at Ferry Bridge. A ferry boat was used to connect Portland to the mainland, until the first bridge was constructed in 1839. An iron bridge replaced this in 1896, this was in turn replaced with a concrete bridge in 1985. Both Chesil Beach and the Fleet Lagoon are a Site of Special Scientific Interest, the view of the beach from Abbotsbury has been voted by Country Life magazine as Britain's third best view.
The Fleet Lagoon and Chesil Beach feature in the novel Moonfleet by J. Meade Falkner, in which the village of Moonfleet is based on the real village of Fleet. An arrangement of nets and p
In earth science, erosion is the action of surface processes that removes soil, rock, or dissolved material from one location on the Earth's crust, transports it to another location. This natural process is caused by the dynamic activity of erosive agents, that is, ice, air, plants and humans. In accordance with these agents, erosion is sometimes divided into water erosion, glacial erosion, snow erosion, wind erosion, zoogenic erosion, anthropogenic erosion; the particulate breakdown of rock or soil into clastic sediment is referred to as physical or mechanical erosion. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Natural rates of erosion are controlled by the action of geological weathering geomorphic drivers, such as rainfall; the rates at which such processes act control. Physical erosion proceeds fastest on steeply sloping surfaces, rates may be sensitive to some climatically-controlled properties including amounts of water supplied, wind speed, wave fetch, or atmospheric temperature.
Feedbacks are possible between rates of erosion and the amount of eroded material, carried by, for example, a river or glacier. Processes of erosion that produce sediment or solutes from a place contrast with those of deposition, which control the arrival and emplacement of material at a new location. While erosion is a natural process, human activities have increased by 10-40 times the rate at which erosion is occurring globally. At well-known agriculture sites such as the Appalachian Mountains, intensive farming practices have caused erosion up to 100x the speed of the natural rate of erosion in the region. Excessive erosion causes both "on-site" and "off-site" problems. On-site impacts include decreases in agricultural productivity and ecological collapse, both because of loss of the nutrient-rich upper soil layers. In some cases, the eventual end result is desertification. Off-site effects include sedimentation of waterways and eutrophication of water bodies, as well as sediment-related damage to roads and houses.
Water and wind erosion are the two primary causes of land degradation. Intensive agriculture, roads, anthropogenic climate change and urban sprawl are amongst the most significant human activities in regard to their effect on stimulating erosion. However, there are many prevention and remediation practices that can curtail or limit erosion of vulnerable soils. Rainfall, the surface runoff which may result from rainfall, produces four main types of soil erosion: splash erosion, sheet erosion, rill erosion, gully erosion. Splash erosion is seen as the first and least severe stage in the soil erosion process, followed by sheet erosion rill erosion and gully erosion. In splash erosion, the impact of a falling raindrop creates a small crater in the soil, ejecting soil particles; the distance these soil particles travel can be as much as 0.6 m vertically and 1.5 m horizontally on level ground. If the soil is saturated, or if the rainfall rate is greater than the rate at which water can infiltrate into the soil, surface runoff occurs.
If the runoff has sufficient flow energy, it will transport loosened soil particles down the slope. Sheet erosion is the transport of loosened soil particles by overland flow. Rill erosion refers to the development of small, ephemeral concentrated flow paths which function as both sediment source and sediment delivery systems for erosion on hillslopes. Where water erosion rates on disturbed upland areas are greatest, rills are active. Flow depths in rills are of the order of a few centimetres or less and along-channel slopes may be quite steep; this means that rills exhibit hydraulic physics different from water flowing through the deeper, wider channels of streams and rivers. Gully erosion occurs when runoff water accumulates and flows in narrow channels during or after heavy rains or melting snow, removing soil to a considerable depth. Valley or stream erosion occurs with continued water flow along a linear feature; the erosion is both downward, deepening the valley, headward, extending the valley into the hillside, creating head cuts and steep banks.
In the earliest stage of stream erosion, the erosive activity is dominantly vertical, the valleys have a typical V cross-section and the stream gradient is steep. When some base level is reached, the erosive activity switches to lateral erosion, which widens the valley floor and creates a narrow floodplain; the stream gradient becomes nearly flat, lateral deposition of sediments becomes important as the stream meanders across the valley floor. In all stages of stream erosion, by far the most erosion occurs during times of flood when more and faster-moving water is available to carry a larger sediment load. In such processes, it is not the water alone
Mary Anning was an English fossil collector and palaeontologist who became known around the world for important finds she made in Jurassic marine fossil beds in the cliffs along the English Channel at Lyme Regis in the county of Dorset in Southwest England. Her findings contributed to important changes in scientific thinking about prehistoric life and the history of the Earth. Anning searched for fossils in the area's Blue Lias cliffs during the winter months when landslides exposed new fossils that had to be collected before they were lost to the sea, she nearly died in 1833 during a landslide. Her discoveries included the first ichthyosaur skeleton identified, her observations played a key role in the discovery that coprolites, known as bezoar stones at the time, were fossilised faeces. She discovered that belemnite fossils contained fossilised ink sacs like those of modern cephalopods; when geologist Henry De la Beche painted Duria Antiquior, the first circulated pictorial representation of a scene from prehistoric life derived from fossil reconstructions, he based it on fossils Anning had found, sold prints of it for her benefit.
A Dissenter and a woman, Anning did not participate in the scientific community of 19th-century Britain, who were Anglican gentlemen. She struggled financially for much of her life, her family was poor, her father, a cabinetmaker, died when she was eleven. She became well known in geological circles in Britain and America, was consulted on issues of anatomy as well as about collecting fossils. Nonetheless, as a woman, she was not eligible to join the Geological Society of London and she did not always receive full credit for her scientific contributions. Indeed, she wrote in a letter: "The world has used me so unkindly, I fear it has made me suspicious of everyone." The only scientific writing of hers published in her lifetime appeared in the Magazine of Natural History in 1839, an extract from a letter that Anning had written to the magazine's editor questioning one of its claims. After her death in 1847, her unusual life story attracted increasing interest. An uncredited author in All the Year Round, edited by Charles Dickens, wrote of her in 1865 that "he carpenter's daughter has won a name for herself, has deserved to win it."
It has been claimed that her story was the inspiration for the 1908 tongue-twister "She sells seashells on the seashore" by Terry Sullivan. In 2010, one hundred and sixty-three years after her death, the Royal Society included Anning in a list of the ten British women who have most influenced the history of science. Anning was born in Lyme Regis in England, her father, Richard Anning, was a cabinetmaker who supplemented his income by mining the coastal cliff-side fossil beds near the town, selling his finds to tourists. He married Mary Moore, known on 8 August 1793 in Blandford Forum; the couple lived in a house built on the town's bridge. They attended the Dissenter chapel on Coombe Street, whose worshippers called themselves independents and became known as Congregationalists. Shelley Emling writes that the family lived so near to the sea that the same storms that swept along the cliffs to reveal the fossils sometimes flooded the Annings' home, on one occasion forcing them to crawl out of an upstairs bedroom window to avoid being drowned.
Richard and Molly had ten children. The first child, was born in 1794, she was followed by another girl, who died at once. In December that year, the oldest child four years old, died after her clothes caught fire while adding wood shavings to the fire; the incident was reported in the Bath Chronicle on 27 December 1798: "A child, four years of age of Mr. R. Anning, a cabinetmaker of Lyme, was left by the mother for about five minutes... in a room where there were some shavings... The girl's clothes caught fire and she was so dreadfully burnt as to cause her death." When another daughter was born just five months she was named Mary after her dead sister. More children were born after her. Only Mary and Joseph survived to adulthood; the high childhood mortality rate for the Anning family was not unusual. Half the children born in Britain throughout the 19th century died before the age of 5, in the crowded living conditions of early 19th century Lyme Regis, infant deaths from diseases like smallpox and measles were common.
On 19 August 1800, when Anning was 15 months old, an event occurred. She was being held by a neighbour, Elizabeth Haskings, standing with two other women under an elm tree watching an equestrian show being put on by a travelling company of horsemen, when lightning struck the tree killing all three women below. Onlookers rushed the infant home. A local doctor declared her survival miraculous, her family said she had been a sickly baby before the event but afterwards she seemed to blossom. For years afterward members of her community would attribute the child's curiosity and lively personality to the incident, her education was limited. She was able to attend a Congregationalist Sunday school where she learned to write. Congregationalist doctrine, unlike that of the Church of England at the time, emphasised the importance of education for the poor, her prized possession was a bound volume of the Dissenters' Theological Magazine and Re
Ammonoids are an extinct group of marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs referred to as ammonites, are more related to living coleoids than they are to shelled nautiloids such as the living Nautilus species; the earliest ammonites appear during the Devonian, the last species died out in the Cretaceous–Paleogene extinction event. Ammonites are excellent index fossils, it is possible to link the rock layer in which a particular species or genus is found to specific geologic time periods, their fossil shells take the form of planispirals, although there were some helically spiraled and nonspiraled forms. The name "ammonite", from which the scientific term is derived, was inspired by the spiral shape of their fossilized shells, which somewhat resemble coiled rams' horns. Pliny the Elder called fossils of these animals ammonis cornua because the Egyptian god Ammon was depicted wearing ram's horns; the name of an ammonite genus ends in -ceras, Greek for "horn".
Ammonites can be distinguished by their septa, the dividing walls that separate the chambers in the phragmocone, by the nature of their sutures where the septa joint the outer shell wall, in general by their siphuncles. Ammonoid septa characteristically have bulges and indentations and are to varying degrees convex from the front, distinguishing them from nautiloid septa which are simple concave dish-shaped structures; the topology of the septa around the rim, results in the various suture patterns found. Three major types of suture patterns are found in the Ammonoidea: Goniatitic - numerous undivided lobes and saddles; this pattern is characteristic of the Paleozoic ammonoids. Ceratitic - lobes have subdivided tips, giving them a saw-toothed appearance, rounded undivided saddles; this suture pattern is characteristic of Triassic ammonoids and appears again in the Cretaceous "pseudoceratites". Ammonitic - lobes and saddles are much subdivided. Ammonoids of this type are the most important species from a biostratigraphical point of view.
This suture type is characteristic of Jurassic and Cretaceous ammonoids, but extends back all the way to the Permian. The siphuncle in most ammonoids is a narrow tubular structure that runs along the shell's outer rim, known as the venter, connecting the chambers of the phragmocone to the body or living chamber; this distinguishes them from living nautiloides and typical Nautilida, in which the siphuncle runs through the center of each chamber. However the earliest nautiloids from the Late Cambrian and Ordovician had ventral siphuncles like ammonites, although proportionally larger and more internally structured; the word "siphuncle" comes from the New Latin siphunculus, meaning "little siphon". Originating from within the bactritoid nautiloids, the ammonoid cephalopods first appeared in the Devonian and became extinct at the close of the Cretaceous along with the dinosaurs; the classification of ammonoids is based in part on the ornamentation and structure of the septa comprising their shells' gas chambers.
While nearly all nautiloids show curving sutures, the ammonoid suture line is variably folded, forming saddles and lobes. The Ammonoidea can be divided into six orders, listed here starting with the most primitive and going to the more derived: Agoniatitida, Lower Devonian - Middle Devonian Clymeniida, Upper Devonian Goniatitida, Middle Devonian - Upper Permian Prolecanitida, Upper Devonian - Upper Triassic Ceratitida, Upper Permian - Upper Triassic Ammonitida, Lower Jurassic - Upper CretaceousIn some classifications, these are left as suborders, included in only three orders: Goniatitida and Ammonitida; the Treatise on Invertebrate Paleontology divides the Ammonoidea, regarded as an order, into eight suborders, the Anarcestina, Clymeniina and Prolecanitina from the Paleozoic. In subsequent taxonomies, these are sometimes regarded as orders within the subclass Ammonoidea; because ammonites and their close relatives are extinct, little is known about their way of life. Their soft body parts are rarely preserved in any detail.
Nonetheless, much has been worked out by examining ammonoid shells and by using models of these shells in water tanks. Many ammonoids lived in the open water of ancient seas, rather than at the sea bottom, because their fossils are found in rocks laid down under conditions where no bottom-dwelling life is found. Many of them are thought to have been good swimmers, with flattened, discus-shaped, streamlined shells, although some ammonoids were less effective swimmers and were to have been slow-swimming bottom-dwellers. Synchrotron analysis of an aptychophoran ammonite revealed remains of isopod and mollusc larvae in its buccal cavity, indicating at least this kind of ammonite fed on plankton, they may have avoided predation by squirting ink, much like modern cephalopods. The soft body of the creature occupied the largest segments of the shell at the end of the coil; the smaller earlier segments were walled off and the animal could maintain its buoyancy by filling them with gas. Thus, the smaller sections of the coil would have floated ab