Hadrosaurids, or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts; the family, which includes ornithopods such as Edmontosaurus and Parasaurolophus, was a common group of herbivores during the Late Cretaceous Period in what is now Asia, Antarctica, South America, North America. Hadrosaurids are descendants of the Upper Jurassic/Lower Cretaceous iguanodontian dinosaurs and had a similar body layout. Like other ornithischians, hadrosaurids had a predentary bone and a pubic bone, positioned backwards in the pelvis. Hadrosauridae is divided into two principal subfamilies: the lambeosaurines, which had hollow cranial crests or tubes. Saurolophines tended to be bulkier than lambeosaurines. Lambeosaurines included the aralosaurins, tsintaosaurins and parasaurolophins, while saurolophines included the brachylophosaurins, kritosaurins and edmontosaurins. Hadrosaurids were facultative bipeds, with the young of some species walking on two legs and the adults walking on four.
Their jaws were evolved for grinding plants, with multiple rows of teeth replacing each other as the teeth wore down. Hadrosaurids were the first dinosaur family to be identified in North America - the first traces being found in 1855-1856 with the discovery of fossil teeth. Joseph Leidy examined the teeth, erected the genera Trachodon and Thespesius. One species was named Trachodon mirabilis. Trachodon included all sorts of cerapod dinosaurs, including ceratopsids, is now considered an invalid genus. In 1858, the teeth were associated with Leidy's eponymous Hadrosaurus foulkii, named after the fossil hobbyist William Parker Foulke. More and more teeth were found, resulting in more genera. A well preserved complete hadrosaurid specimen, AMNH 5060, was recovered in 1908 by the fossil collector Charles Hazelius Sternberg and his three sons, in Converse County, Wyoming. Analyzed by Henry Osborn in 1912, it has come to be known as the "Trachodon mummy"; this specimen's skin was completely preserved in the form of impressions.
The family Hadrosauridae was first used by Edward Drinker Cope in 1869. Since its creation, a major division has been recognized in the group between the hollow-crested subfamily Lambeosaurinae and the subfamily Saurolophinae known as Hadrosaurinae. Both of these have been robustly support in all recent literature. Phylogenetic analysis has increased the resolution of hadrosaurid relationships leading to the widespread usage of tribes to describe the finer relationships within each group of hadrosaurids.. Lambeosaurines have been traditionally split into Parasaurolophini and Lambeosaurini; these terms entered the formal literature in Evans and Reisz's 2007 redescription of Lambeosaurus magnicristatus. Lambeosaurini is defined as all taxa more related Lambeosaurus lambei than to Parasaurolophus walkeri, Parasaurolophini as all those taxa closer to P. walkeri than to L. lambei. In recent years Tsintaosaurini and Aralosaurini have emerged; the use of the term Hadrosaurinae was questioned in a comprehensive study of hadrosaurid relationships by Albert Prieto-Márquez in 2010.
Prieto-Márquez noted that, though the name Hadrosaurinae had been used for the clade of crestless hadrosaurids by nearly all previous studies, its type species, Hadrosaurus foulkii, has always been excluded from the clade that bears its name, in violation of the rules for naming animals set out by the ICZN. Prieto-Márquez defined Hadrosaurinae as just the lineage containing H. foulkii, used the name Saurolophinae instead for the traditional grouping. Hadrosauridae was first defined as a clade, by Forster, in a 1997 abstract, as "Lambeosaurinae plus Hadrosaurinae and their most recent common ancestor". In 1998, Paul Sereno defined the clade Hadrosauridae as the most inclusive possible group containing Saurolophus and Parasaurolophus emending the definition to include Hadrosaurus, the type genus of the family, which ICZN rules state must be included, despite its status as a nomen dubium. According to Horner et al. Sereno's definition would place a few other well-known hadrosaurs outside the family, which led them to define the family to include Telmatosaurus by default.
Prieto-Marquez reviewed the phylogeny of Hadrosauridae in 2010, including many taxa within the family. Below is a cladogram from al.. 2016. This cladogram is a recent modification of the original 2010 analysis, including more characters and taxa; the resulting cladistic tree of their analysis was resolved using Maximum-Parsimony. 61 hadrosauroid species were included, characterized for 273 morphological features: 189 for cranial features and 84 for postcranial features. When characters had multiple states that formed an evolutionary scheme, they were ordered to account for the evolution of one state into the next; the final tree was run through TNT version 1.0. The most recognizable aspect of hadrosaur anatomy is the flattened and laterally stretched rostral bones, which gives the distinct duck-bill look, some members of the hadrosaurs had massive crests on their heads for display. In some genera, including Edmontosaurus, the whole fron
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals have mouthparts adapted to rasping or grinding. Horses and other herbivores have wide flat teeth that are adapted to grinding grass, tree bark, other tough plant material. A large percentage of herbivores have mutualistic gut flora that help them digest plant matter, more difficult to digest than animal prey; this flora is made up of cellulose-digesting bacteria. Herbivore is the anglicized form of a modern Latin coinage, cited in Charles Lyell's 1830 Principles of Geology. Richard Owen employed the anglicized term in an 1854 work on fossil skeletons. Herbivora is derived from the Latin herba meaning a small plant or herb, vora, from vorare, to eat or devour. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants and photosynthesizing bacteria.
More organisms that feed on autotrophs in general are known as primary consumers. Herbivory is limited to animals that eat plants. Fungi and protists that feed on living plants are termed plant pathogens, while fungi and microbes that feed on dead plants are described as saprotrophs. Flowering plants that obtain nutrition from other living plants are termed parasitic plants. There is, however, no single exclusive and definitive ecological classification of consumption patterns. In zoology, an herbivore is an animal, adapted to eat plant matter. Our understanding of herbivory in geological time comes from three sources: fossilized plants, which may preserve evidence of defence, or herbivory-related damage. Although herbivory was long thought to be a Mesozoic phenomenon, fossils have shown that within less than 20 million years after the first land plants evolved, plants were being consumed by arthropods. Insects fed on the spores of early Devonian plants, the Rhynie chert provides evidence that organisms fed on plants using a "pierce and suck" technique.
During the next 75 million years, plants evolved a range of more complex organs, such as roots and seeds. There is no evidence of any organism being fed upon until the middle-late Mississippian, 330.9 million years ago. There was a gap of 50 to 100 million years between the time each organ evolved and the time organisms evolved to feed upon them. Further than their arthropod status, the identity of these early herbivores is uncertain. Hole feeding and skeletonisation are recorded in the early Permian, with surface fluid feeding evolving by the end of that period. Herbivory among four-limbed terrestrial vertebrates, the tetrapods developed in the Late Carboniferous. Early tetrapods were large amphibious piscivores. While amphibians continued to feed on fish and insects, some reptiles began exploring two new food types and plants; the entire dinosaur order ornithischia was composed with herbivores dinosaurs. Carnivory was a natural transition from insectivory for medium and large tetrapods, requiring minimal adaptation.
In contrast, a complex set of adaptations was necessary for feeding on fibrous plant materials. Arthropods evolved herbivory in four phases, changing their approach to it in response to changing plant communities. Tetrapod herbivores made their first appearance in the fossil record of their jaws near the Permio-Carboniferous boundary 300 million years ago; the earliest evidence of their herbivory has been attributed to dental occlusion, the process in which teeth from the upper jaw come in contact with teeth in the lower jaw is present. The evolution of dental occlusion led to a drastic increase in plant food processing and provides evidence about feeding strategies based on tooth wear patterns. Examination of phylogenetic frameworks of tooth and jaw morphologes has revealed that dental occlusion developed independently in several lineages tetrapod herbivores; this suggests that evolution and spread occurred within various lineages. Herbivores form an important link in the food chain because they consume plants in order to digest the carbohydrates photosynthetically produced by a plant.
Carnivores in turn consume herbivores for the same reason, while omnivores can obtain their nutrients from either plants or animals. Due to a herbivore's ability to survive on tough and fibrous plant matter, they are termed the primary consumers in the food cycle. Herbivory and omnivory can be regarded as special cases of Consumer-Resource Systems. Herbivores come in all sizes in the animal kingdom, they include aquatic and non-aquatic vertebrates. They can be large, like an elephant. Many herbivores found living in close proximity to humans, such as rodents, cows and camels. Two herbivore feeding strategies are browsing. For a terrestrial mammal to be called a grazer, at least 90% of the forage has to be grass, for a browser at least 90% tree leaves and/or twigs. An intermediate feeding strategy is called "mixed-feeding". In their daily need to take up energy from forage, herbivores of different body mass may be selective in choosing their food. "Selective" means that herbivores may choose their forage source depending on, e.g. season or food avail
North America is a continent within the Northern Hemisphere and all within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, to the southeast by South America and the Caribbean Sea. North America covers an area of about 24,709,000 square kilometers, about 16.5% of the earth's land area and about 4.8% of its total surface. North America is the third largest continent by area, following Asia and Africa, the fourth by population after Asia and Europe. In 2013, its population was estimated at nearly 579 million people in 23 independent states, or about 7.5% of the world's population, if nearby islands are included. North America was reached by its first human populations during the last glacial period, via crossing the Bering land bridge 40,000 to 17,000 years ago; the so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago. The Classic stage spans the 6th to 13th centuries.
The Pre-Columbian era ended in 1492, the transatlantic migrations—the arrival of European settlers during the Age of Discovery and the Early Modern period. Present-day cultural and ethnic patterns reflect interactions between European colonists, indigenous peoples, African slaves and their descendants. Owing to the European colonization of the Americas, most North Americans speak English, Spanish or French, their culture reflects Western traditions; the Americas are accepted as having been named after the Italian explorer Amerigo Vespucci by the German cartographers Martin Waldseemüller and Matthias Ringmann. Vespucci, who explored South America between 1497 and 1502, was the first European to suggest that the Americas were not the East Indies, but a different landmass unknown by Europeans. In 1507, Waldseemüller produced a world map, in which he placed the word "America" on the continent of South America, in the middle of what is today Brazil, he explained the rationale for the name in the accompanying book Cosmographiae Introductio:... ab Americo inventore... quasi Americi terram sive Americam.
For Waldseemüller, no one should object to the naming of the land after its discoverer. He used the Latinized version of Vespucci's name, but in its feminine form "America", following the examples of "Europa", "Asia" and "Africa". Other mapmakers extended the name America to the northern continent, In 1538, Gerard Mercator used America on his map of the world for all the Western Hemisphere; some argue that because the convention is to use the surname for naming discoveries, the derivation from "Amerigo Vespucci" could be put in question. In 1874, Thomas Belt proposed a derivation from the Amerrique mountains of Central America. Marcou corresponded with Augustus Le Plongeon, who wrote: "The name AMERICA or AMERRIQUE in the Mayan language means, a country of perpetually strong wind, or the Land of the Wind, and... the can mean... a spirit that breathes, life itself." The United Nations formally recognizes "North America" as comprising three areas: Northern America, Central America, The Caribbean.
This has been formally defined by the UN Statistics Division. The term North America maintains various definitions in accordance with context. In Canadian English, North America refers to the land mass as a whole consisting of Mexico, the United States, Canada, although it is ambiguous which other countries are included, is defined by context. In the United States of America, usage of the term may refer only to Canada and the US, sometimes includes Greenland and Mexico, as well as offshore islands. In France, Portugal, Romania and the countries of Latin America, the cognates of North America designate a subcontinent of the Americas comprising Canada, the United States, Mexico, Greenland, Saint Pierre et Miquelon, Bermuda. North America has been referred to by other names. Spanish North America was referred to as Northern America, this was the first official name given to Mexico. Geographically the North American continent has many subregions; these include cultural and geographic regions. Economic regions included those formed by trade blocs, such as the North American Trade Agreement bloc and Central American Trade Agreement.
Linguistically and culturally, the continent could be divided into Latin America. Anglo-America includes most of Northern America and Caribbean islands with English-speaking populations; the southern North American continent is composed of two regions. These are the Caribbean; the north of the continent maintains recognized regions as well. In contrast to the common definition of "North America", which encompasses the whole continent, the term "North America" is sometimes used to refer only to Mexico, the United States, Greenland; the term Northern America refers to the northern-most countries and territories of North America: the United States, Bermuda, St. Pierre and Miquelon and Greenland. Although the term does not refer to a unifie
Sauropoda, or the sauropods, are a clade of saurischian dinosaurs. They had long necks, long tails, small heads, four thick, pillar-like legs, they are notable for the enormous sizes attained by some species, the group includes the largest animals to have lived on land. Well-known genera include Brachiosaurus, Diplodocus and Brontosaurus. Sauropods first appeared in the late Triassic Period, where they somewhat resembled the related group "Prosauropoda". By the Late Jurassic, sauropods had become widespread. By the Late Cretaceous, those groups had been replaced by the titanosaurs, which had a near-global distribution. However, as with all other non-avian dinosaurs alive at the time, the titanosaurs died out in the Cretaceous–Paleogene extinction event. Fossilised remains of sauropods have been found on every continent, including Antarctica; the name Sauropoda was coined by O. C. Marsh in 1878, is derived from Greek, meaning "lizard foot". Sauropods are one of the most recognizable groups of dinosaurs, have become a fixture in popular culture due to their large sizes.
Complete sauropod fossil finds are rare. Many species the largest, are known only from isolated and disarticulated bones. Many near-complete specimens lack tail tips and limbs. Sauropods were herbivorous quite long-necked quadrupeds with spatulate teeth, they had tiny heads, massive bodies, most had long tails. Their hind legs were thick and powerful, ending in club-like feet with five toes, though only the inner three bore claws, their forelimbs were rather more slender and ended in pillar-like hands built for supporting weight. Many illustrations of sauropods in the flesh miss these facts, inaccurately depicting sauropods with hooves capping the claw-less digits of the feet, or more than three claws or hooves on the hands; the proximal caudal vertebrae are diagnostic for sauropods. The sauropods' most defining characteristic was their size; the dwarf sauropods were counted among the largest animals in their ecosystem. Their only real competitors in terms of size are the rorquals, such as the blue whale.
But, unlike whales, sauropods were terrestrial animals. Their body structure did not vary as much as other dinosaurs due to size constraints, but they displayed ample variety. Some, like the diplodocids, possessed tremendously long tails, which they may have been able to crack like a whip as a signal or to deter or injure predators, or to make sonic booms. Supersaurus, at 33 to 34 metres long, was the longest sauropod known from reasonably complete remains, but others, like the old record holder, were extremely long; the holotype vertebra of Amphicoelias fragillimus may have come from an animal 58 metres long. However, a research published in 2015 speculated that the size estimates of A. fragillimus may have been exaggerated. The longest dinosaur known from reasonable fossils material is Argentinosaurus huinculensis with length estimates of 25 metres to 39.7 metres. The longest terrestrial animal alive today, the reticulated python, only reaches lengths of 6.95 metres. Others, like the brachiosaurids, were tall, with high shoulders and long necks.
Sauroposeidon was the tallest, reaching about 18 metres high, with the previous record for longest neck being held by Mamenchisaurus. By comparison, the giraffe, the tallest of all living land animals, is only 4.8 to 5.5 metres tall. The best evidence indicates that the most massive were Argentinosaurus, Alamosaurus, Antarctosaurus. There was poor evidence that so-called Bruhathkayosaurus, might have weighed over 175 metric tons but this has been questioned; the weight of Amphicoelias fragillimus was estimated at 122.4 metric tons but 2015 research argued that these estimates may have been exaggerated. The largest land animal alive today, the Savannah elephant, weighs no more than 10.4 metric tons. Among the smallest sauropods were the primitive Ohmdenosaurus, the dwarf titanosaur Magyarosaurus, the dwarf brachiosaurid Europasaurus, 6.2 meters long as a fully-grown adult. Its small stature was the result of insular dwarfism occurring in a population of sauropods isolated on an island of the late Jurassic in what is now the Langenberg area of northern Germany.
The diplodocoid sauropod Brachytrachelopan was the shortest member of its group because of its unusually short neck. Unlike other sauropods, whose necks could grow to up to four times the length of their backs, the neck of Brachytrachelopan was shorter than its backbone. On or shortly before 29 March 2017 a sauropod footprint about 5.6 feet long was found at Walmadany in the Kimberley Region of Western Australia. The report said; as massive quadrupeds, sauropods developed specialized graviportal limbs. The hind feet were broad, retained three claws in most species. Unusual compared with other animals were the modified front feet; the front feet of sauropods were dissimilar from those of modern
Stenopelix is a genus of small marginocephalian dinosaur a basal ceratopsian, from the Early Cretaceous of Germany. It lived in the Barremian Stage of the Cretaceous period, sometime between 130 and 125 million years ago; the genus is based on a partial skeleton lacking the skull, its classification is based on characteristics of the hips. In 1855, in a sandstone quarry near Bückeburg on the Harrl, a fossil was found of a small dinosaur. Most of its bones were in a poor condition and removed on preparation, leaving two sets of hollow impressions on the plate and counterplate; the two plates do not overlap completely. The hollows, serving as a natural mold, have since been used to produce several casts in gypsum and latex to facilitate the study of the specimen, it was part of the collection of Max Ballerstedt preserved in the Bückeburg Gymnsasium Adolfinum but was in 1976 moved to the Georg-August-Universität Göttingen where it now resides in the collection of the Geowissenschaftliches Zentrum der Universität Göttingen.
In 1857, based on this fossil, Christian Erich Hermann von Meyer named the type species Stenopelix valdensis. The generic name is derived from Greek stenos, "narrow", pelyx, "pelvis"; the specific name refers to the Wealden Formation. The holotype, GZG 741/2, found in the Obernkirchen Sandstein Formation, consists of the impressions of an complete skeleton, lacking the skull and the neck; the classification of Stenopelix is controversial and has been problematic because of the lacking skull. Prior to the 1960s, it was assigned to some ornithopod group. In 1974 Teresa Maryańska suggested it to be a pachycephalosaur, one of the oldest known, due to the apparent exclusion of the pubis from the acetabulum, the presence of strong caudal ribs. Peter Galton in 1982 showed that the "pubis" was part of the acetabulum, the so-called "caudal ribs" were sacral ribs; the curvature of the ischium and absence of an obturator foramen were not characteristics seen in other pachycephalosaurs. Galton concluded Stenopelix to be ceratopian.
However, exact cladistic analyses by Paul Sereno have resulted in a position in the Pachycephalosauria. But paleontologists Richard J. Butler and Robert M. Sullivan nonetheless view the species as being Marginocephalia incertae sedis, rejecting the presumed synapomorphies with the Pachycephalosauria as incorrect identifications or lacking cogency because of a possible presence in ceratopsian groups. In 2011, cladistic analysis performed by Butler et al. showed that Stenopelix is a basal member of the Ceratopsia, its sister taxon is Yinlong. Stenopelix was a small herbivorous animal; the preserved rump and tail have a combined length of just 97 centimetres. The species can be distinguished by several details of the pelvis; the shaft part of the ilium uniformly tapers ending in a rounded point. The shaft of the ischium is thickest in the middle and there shows a distinctive kink. Timeline of ceratopsian research
The Triassic is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.9 million years ago, to the beginning of the Jurassic Period 201.3 Mya. The Triassic is the shortest period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events. Triassic began in the wake of the Permian–Triassic extinction event, which left the Earth's biosphere impoverished. Therapsids and archosaurs were the chief terrestrial vertebrates during this time. A specialized subgroup of archosaurs, called dinosaurs, first appeared in the Late Triassic but did not become dominant until the succeeding Jurassic Period; the first true mammals, themselves a specialized subgroup of therapsids evolved during this period, as well as the first flying vertebrates, the pterosaurs, like the dinosaurs, were a specialized subgroup of archosaurs. The vast supercontinent of Pangaea existed until the mid-Triassic, after which it began to rift into two separate landmasses, Laurasia to the north and Gondwana to the south.
The global climate during the Triassic was hot and dry, with deserts spanning much of Pangaea's interior. However, the climate became more humid as Pangaea began to drift apart; the end of the period was marked by yet another major mass extinction, the Triassic–Jurassic extinction event, that wiped out many groups and allowed dinosaurs to assume dominance in the Jurassic. The Triassic was named in 1834 by Friedrich von Alberti, after the three distinct rock layers that are found throughout Germany and northwestern Europe—red beds, capped by marine limestone, followed by a series of terrestrial mud- and sandstones—called the "Trias"; the Triassic is separated into Early and Late Triassic Epochs, the corresponding rocks are referred to as Lower, Middle, or Upper Triassic. The faunal stages from the youngest to oldest are: During the Triassic all the Earth's land mass was concentrated into a single supercontinent centered more or less on the equator and spanning from pole to pole, called Pangaea.
From the east, along the equator, the Tethys sea penetrated Pangaea, causing the Paleo-Tethys Ocean to be closed. In the mid-Triassic a similar sea penetrated along the equator from the west; the remaining shores were surrounded by the world-ocean known as Panthalassa. All the deep-ocean sediments laid down during the Triassic have disappeared through subduction of oceanic plates; the supercontinent Pangaea was rifting during the Triassic—especially late in that period—but had not yet separated. The first nonmarine sediments in the rift that marks the initial break-up of Pangaea, which separated New Jersey from Morocco, are of Late Triassic age. S. these thick sediments comprise the Newark Group. Because a super-continental mass has less shoreline compared to one broken up, Triassic marine deposits are globally rare, despite their prominence in Western Europe, where the Triassic was first studied. In North America, for example, marine deposits are limited to a few exposures in the west, thus Triassic stratigraphy is based on organisms that lived in lagoons and hypersaline environments, such as Estheria crustaceans.
At the beginning of the Mesozoic Era, Africa was joined with Earth's other continents in Pangaea. Africa shared the supercontinent's uniform fauna, dominated by theropods and primitive ornithischians by the close of the Triassic period. Late Triassic fossils are more common in the south than north; the time boundary separating the Permian and Triassic marks the advent of an extinction event with global impact, although African strata from this time period have not been studied. During the Triassic peneplains are thought to have formed in what is now southern Sweden. Remnants of this peneplain can be traced as a tilted summit accordance in the Swedish West Coast. In northern Norway Triassic peneplains may have been buried in sediments to be re-exposed as coastal plains called strandflats. Dating of illite clay from a strandflat of Bømlo, southern Norway, have shown that landscape there became weathered in Late Triassic times with the landscape also being shaped during that time. At Paleorrota geopark, located in Rio Grande do Sul, the Santa Maria Formation and Caturrita Formations are exposed.
In these formations, one of the earliest dinosaurs, Staurikosaurus, as well as the mammal ancestors Brasilitherium and Brasilodon have been discovered. The Triassic continental interior climate was hot and dry, so that typical deposits are red bed sandstones and evaporites. There is no evidence of glaciation near either pole. Pangaea's large size limited the moderating effect of the global ocean; the strong contrast between the Pangea supercontinent and the global ocean triggered intense cross-equatorial monsoons. The Triassic may have been a dry period, but evidence exists that it was punctuated by several episodes of increased rainfall in tropical and subtropical latitudes of the Tethys Sea and its surrounding land. Sediments and fossils suggestive of a more humid climate are known from the Anisian to Ladinian of the Tethysian domain, from the Carnian and Rhaetian of a larger area that includes the Boreal domain, the North
Thomas Henry Huxley
Thomas Henry Huxley was an English biologist and anthropologist specialising in comparative anatomy. He is known as "Darwin's Bulldog" for his advocacy of Charles Darwin's theory of evolution; the stories regarding Huxley's famous debate in 1860 with Samuel Wilberforce were a key moment in the wider acceptance of evolution and in his own career, although historians think that the surviving story of the debate is a fabrication. Huxley had been planning to leave Oxford on the previous day, after an encounter with Robert Chambers, the author of Vestiges, he changed his mind and decided to join the debate. Wilberforce was coached by Richard Owen, against whom Huxley debated about whether humans were related to apes. Huxley was slow to accept some of Darwin's ideas, such as gradualism, was undecided about natural selection, but despite this he was wholehearted in his public support of Darwin. Instrumental in developing scientific education in Britain, he fought against the more extreme versions of religious tradition.
Coining the term in 1869, Huxley elaborated on "agnosticism" in 1889 to frame the nature of claims in terms of what is knowable and what is not. Huxley statesAgnosticism, in fact, is not a creed, but a method, the essence of which lies in the rigorous application of a single principle... the fundamental axiom of modern science... In matters of the intellect, follow your reason as far as it will take you, without regard to any other consideration... In matters of the intellect, do not pretend that conclusions are certain which are not demonstrated or demonstrable. Use of that term has continued to the present day. Much of Huxley's agnosticism is influenced by Kantian views on human perception and the ability to rely on rational evidence rather than belief systems. Huxley had little formal schooling and was self-taught, he became the finest comparative anatomist of the 19th century. He worked on invertebrates, clarifying relationships between groups little understood, he worked on vertebrates on the relationship between apes and humans.
After comparing Archaeopteryx with Compsognathus, he concluded that birds evolved from small carnivorous dinosaurs, a theory accepted today. The tendency has been for this fine anatomical work to be overshadowed by his energetic and controversial activity in favour of evolution, by his extensive public work on scientific education, both of which had significant effects on society in Britain and elsewhere. Huxley’s 1893 Romanes Lecture, “Evolution and Ethics” is exceedingly influential in China. Thomas Henry Huxley was born in Ealing, a village in Middlesex, he was the second youngest of eight children of Rachel Withers. Like some other British scientists of the nineteenth century such as Alfred Russel Wallace, Huxley was brought up in a literate middle-class family which had fallen on hard times, his father was a mathematics teacher at Ealing School until it closed, putting the family into financial difficulties. As a result, Thomas left school after only two years of formal schooling. Huxley's parents were Anglicans, although it was against organized religion Huxley sympathized with the town's Nonconformist.
Despite this unenviable start, Huxley was determined to educate himself. He became one of the great autodidacts of the nineteenth century. At first he read Thomas Carlyle, James Hutton's Geology, Hamilton's Logic. In his teens he taught himself German becoming fluent and used by Charles Darwin as a translator of scientific material in German, he learned Latin, enough Greek to read Aristotle in the original. On, as a young adult, he made himself an expert, first on invertebrates, on vertebrates, all self-taught, he was skilled in drawing and did many of the illustrations for his publications on marine invertebrates. In his debates and writing on science and religion his grasp of theology was better than most of his clerical opponents. Huxley, a boy who left school at ten, became one of the most knowledgeable men in Britain, he was apprenticed for short periods to several medical practitioners: at 13 to his brother-in-law John Cooke in Coventry, who passed him on to Thomas Chandler, notable for his experiments using mesmerism for medical purposes.
Chandler's practice was in London's Rotherhithe amidst the squalor endured by the Dickensian poor. Here Thomas would have seen poverty and rampant disease at its worst. Next, another brother-in-law took him on: his eldest sister's husband. Now 16, Huxley entered Sydenham College, a cut-price anatomy school whose founder, Marshall Hall, discovered the reflex arc. All this time Huxley continued his programme of reading, which more than made up for his lack of formal schooling. A year buoyed by excellent results and a silver medal prize in the Apothecaries' yearly competition, Huxley was admitted to study at Charing Cross Hospital, where he obtained a small scholarship. At Charing Cross, he was taught by Thomas Wharton Jones, Professor of Ophthalmic Medicine and Surgery at University College London. Jones had been Robert Knox's assistant when Knox bought cadavers from Hare; the young Wharton Jones, who acted as go-between, was exonerated of crime, but thought it best to leave Scotland. He was a fine teacher, up-to-date in physiology and an ophthalmic surgeon.
In 1845, under Wharton Jones' guidance, Huxley published his first scientific paper demonstrating the existence of a hitherto unrecognised layer in the inner sheath of hairs, a layer, known sin