A frugivore is an animal that thrives on raw fruits, succulent fruit-like vegetables, shoots and seeds. It can be any type of omnivore where fruit is a preferred food type; because 20% of all mammalian herbivores eat fruit, frugivory is common among mammals. Since frugivores eat a lot of fruit, they are dependent on the abundance and nutritional composition of fruits. Frugivores can either benefit fruit-producing plants by dispersing seeds, or they can hinder plants by digesting seeds along with the fruits; when both the fruit-producing plant and the frugivore species benefit by fruit-eating behavior, their interaction is called mutualism. Seed dispersal is important for plants because it allows their progeny to move away from their parents over time; the advantages of seed dispersal may have led to the evolution of fleshy fruits, which entice animals to eat the fruits and move the plants seeds from place to place. While many fruit-producing plant species would not disperse far without frugivores, they can germinate if they fall to the ground directly below the parent plant.
Many types of animals are seed dispersers. Mammal and bird species represent the majority of seed-dispersing species. However, frugivorous tortoises, lizards and fish disperse seeds. For example, cassowaries are a keystone species because they spread fruit through digestion, many seeds will not grow unless they have been digested by a cassowary. While frugivores and fruit-producing plant species are present worldwide, there is some evidence that tropical forests have more frugivore seed dispersers than the temperate zone. Frugivore seed dispersal is a common phenomenon in many ecosystems. However, it is not a specific type of plant–animal interaction. For example, a single species of frugivorous bird may disperse fruits from several species of plants, or a few species of bird may disperse seeds of one plant species; this lack of specialization could be because fruit availability varies by season and year, which tends to discourage frugivore animals from focusing on just one plant species. Furthermore, different seed dispersers tend to disperse seeds to different habitats, at different abundances, distances, depending on their behavior and numbers.
There are a number of fruit characteristics that seem to be adaptive characteristics to attract frugivores. Many animal-dispersed fruits advertise their palatability to animals with bright colors and attractive smells. Fruit pulp is rich in water and carbohydrates and low in protein and lipids. However, the exact nutritional composition of fruits varies widely; the seeds of animal-dispersed fruits are adapted to survive digestion by frugivores. For example, seeds can become more permeable to water after passage through an animal's gut; this leads to higher germination rates. Some mistletoe seeds germinate inside the disperser's intestine. In order for frugivores to be good seed dispersers, they must digest fruits without consuming a high proportion of the seeds. Many seed-dispersing animals have specialized digestive systems to process fruits, which leave seeds intact; some bird species have shorter intestines to pass seeds from fruits, while some frugivorous bat species have longer intestines. Some seed-dispersing frugivores have short gut-retention times, others can alter intestinal enzyme composition when eating different types of fruits.
Plants invest energy into the production of fruits. Plants have evolved to encourage mutualist frugivores to consume their fruit for seed dispersal, but evolved mechanisms to decrease consumption of fruits when unripe and from non-seed-dispersing predators. Predators and parasites of fruit include seed predators and microbial frugivores. Plants have physical adaptations. Physical deterrents: Cryptic coloration Unpalatable textures Resins and saps Repellent substances, hard outer coats, thornsChemical deterrents: Chemical deterrents in plants are called secondary metabolites. Secondary metabolites are compounds produced by the plant that are not essential for the primary processes, such as growth and reproduction. Toxins might have evolved to prevent consumption by animals that disperse seeds into unsuitable habitats, to prevent too many fruits from being eaten per feeding bout by preventing too many seeds being deposited in one site, or to prevent digestion of the seeds in the gut of the animal.
Secondary chemical defenses are divided into three categories: nitrogen-based, carbon-based terpenes, carbon-based phenolics. Examples of secondary chemical defenses in fruit: Capsaicin is a carbon-based phenolic compound only found in plant genus Capsicum. Capsaicin is responsible for the pungent, hot "flavor" of peppers and inhibits growth of microbes and invertebrates. Cyanogenic glycosides are nitrogen-based compounds and are found in 130 plant families, but not in the fruit of all the plants, it is found in the red berries of the genus Ilex. It can inhibit electron transport, cellular respiration, induce vomiting and mild narcosis in animals. Emodin is a carbon-based phenolic compound in plants like rhubarb. Emodin can be cathartic or act as a laxative in humans, kills dipteran larvae, inhibits growth of bacteria and fungi, deters consumption by birds and mice. Starch is a polysaccharide, converted to fructose as the fruit ripens. Birds are a main focus of frugivory research. An article by B.
A. Loisell and J. G. Blake, Potential Consequences of Extinction of Frugivorous Birds, discusses the im
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them; some animals may scale trees only but others are arboreal. The habitats pose numerous mechanical challenges to animals moving through them and lead to a variety of anatomical and ecological consequences as well as variations throughout different species. Furthermore, many of these same principles may be applied to climbing without trees, such as on rock piles or mountains; the earliest known tetrapod with specializations that adapted it for climbing trees was Suminia, a synapsid of the late Permian, about 260 million years ago. Some animals are arboreal in habitat, such as the tree snail. Arboreal habitats pose numerous mechanical challenges to animals moving in them, which have been solved in diverse ways; these challenges include moving on narrow branches, moving up and down inclines, crossing gaps, dealing with obstructions. Moving along a narrow surface poses special difficulties to animals.
During locomotion on the ground, the location of the center of mass may swing from side to side, but during arboreal locomotion, this would result in the center of mass moving beyond the edge of the branch, resulting in a tendency to topple over. Additionally, foot placement is constrained by the need to make contact with the narrow branch; this narrowness restricts the range of movements and postures an animal can use to move. Branches are oriented at an angle to gravity in arboreal habitats, including being vertical, which poses special problems; as an animal moves up an inclined branch, they must fight the force of gravity to raise their body, making the movement more difficult. Conversely, as the animal descends, it must fight gravity to control its descent and prevent falling. Descent can be problematic for many animals, arboreal species have specialized methods for controlling their descent. Due to the height of many branches and the disastrous consequences of a fall, balance is of primary importance to arboreal animals.
On horizontal and sloped branches, the primary problem is tipping to the side due to the narrow base of support. The narrower the branch, the greater the difficulty in balancing a given animal faces. On steep and vertical branches, tipping becomes less of an issue, pitching backwards or slipping downwards becomes the most failure. In this case, large-diameter branches pose a greater challenge since the animal cannot place its forelimbs closer to the center of the branch than its hindlimbs. Branches are not continuous, any arboreal animal must be able to move between gaps in the branches, or between trees; this can be accomplished by gliding between them. Arboreal habitats contain many obstructions, both in the form of branches emerging from the one being moved on and other branches impinging on the space the animal needs to move through; these obstructions may be used as additional contact points to enhance it. While obstructions tend to impede limbed animals, they benefit snakes by providing anchor points.
Arboreal organisms display many specializations for dealing with the mechanical challenges of moving through their habitats. Arboreal animals have elongated limbs that help them cross gaps, reach fruit or other resources, test the firmness of support ahead, in some cases, to brachiate. However, some species of lizard have reduced limb size that helps them avoid limb movement being obstructed by impinging branches. Many arboreal species, such as tree porcupines, green tree pythons, emerald tree boas, silky anteaters, spider monkeys, possums, use prehensile tails to grasp branches. In the spider monkey and crested gecko, the tip of the tail has either a bare patch or adhesive pad, which provide increased friction. Claws can be used to interact with rough substrates and re-orient the direction of forces the animal applies; this is what allows squirrels to climb tree trunks that are so large as to be flat, from the perspective of such a small animal. However, claws can interfere with an animal's ability to grasp small branches, as they may wrap too far around and prick the animal's own paw.
Adhesion is an alternative to claws. Wet adhesion is common in tree frogs and arboreal salamanders, functions either by suction or by capillary adhesion. Dry adhesion is best typified by the specialized toes of geckos, which use van der Waals forces to adhere to many substrates glass. Frictional gripping is used by primates. Squeezing the branch between the fingertips generates a frictional force that holds the animal's hand to the branch. However, this type of grip depends upon the angle of the frictional force, thus upon the diameter of the branch, with larger branches resulting in reduced gripping ability. Animals other than primates that use gripping in climbing include the chameleon, which has mitten-like grasping feet, many birds that grip branches in perching or moving about. To control descent down large diameter branches, some arboreal animals such as squirrels have evolved mobile ankle joints that permit rotating the foot into a'reversed' posture; this allows the claws to hook into the rough surface of the bark.
Many arboreal species lower their center of mass to reduce pitching and toppling movement when climbing. This may be accomplished by altered body proportions, or smaller size. Small size provides many advantages to arboreal species: such as increasing the relative size of branches
A chordate is an animal constituting the phylum Chordata. During some period of their life cycle, chordates possess a notochord, a dorsal nerve cord, pharyngeal slits, an endostyle, a post-anal tail: these five anatomical features define this phylum. Chordates are bilaterally symmetric; the Chordata and Ambulacraria together form the superphylum Deuterostomia. Chordates are divided into three subphyla: Vertebrata. There are extinct taxa such as the Vetulicolia. Hemichordata has been presented as a fourth chordate subphylum, but now is treated as a separate phylum: hemichordates and Echinodermata form the Ambulacraria, the sister phylum of the Chordates. Of the more than 65,000 living species of chordates, about half are bony fish that are members of the superclass Osteichthyes. Chordate fossils have been found from as early as the Cambrian explosion, 541 million years ago. Cladistically, vertebrates - chordates with the notochord replaced by a vertebral column during development - are considered to be a subgroup of the clade Craniata, which consists of chordates with a skull.
The Craniata and Tunicata compose the clade Olfactores. Chordates form a phylum of animals that are defined by having at some stage in their lives all of the following anatomical features: A notochord, a stiff rod of cartilage that extends along the inside of the body. Among the vertebrate sub-group of chordates the notochord develops into the spine, in wholly aquatic species this helps the animal to swim by flexing its tail. A dorsal neural tube. In fish and other vertebrates, this develops into the spinal cord, the main communications trunk of the nervous system. Pharyngeal slits; the pharynx is the part of the throat behind the mouth. In fish, the slits are modified to form gills, but in some other chordates they are part of a filter-feeding system that extracts particles of food from the water in which the animals live. Post-anal tail. A muscular tail that extends backwards behind the anus. An endostyle; this is a groove in the ventral wall of the pharynx. In filter-feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus.
It stores iodine, may be a precursor of the vertebrate thyroid gland. There are soft constraints that separate chordates from certain other biological lineages, but are not part of the formal definition: All chordates are deuterostomes; this means. All chordates are based on a bilateral body plan. All chordates are coelomates, have a fluid filled body cavity called a coelom with a complete lining called peritoneum derived from mesoderm; the following schema is from the third edition of Vertebrate Palaeontology. The invertebrate chordate classes are from Fishes of the World. While it is structured so as to reflect evolutionary relationships, it retains the traditional ranks used in Linnaean taxonomy. Phylum Chordata †Vetulicolia? Subphylum Cephalochordata – Class Leptocardii Clade Olfactores Subphylum Tunicata – Class Ascidiacea Class Thaliacea Class Appendicularia Class Sorberacea Subphylum Vertebrata Infraphylum incertae sedis Cyclostomata Superclass'Agnatha' paraphyletic Class Myxini Class Petromyzontida or Hyperoartia Class †Conodonta Class †Myllokunmingiida Class †Pteraspidomorphi Class †Thelodonti Class †Anaspida Class †Cephalaspidomorphi Infraphylum Gnathostomata Class †Placodermi Class Chondrichthyes Class †Acanthodii Superclass Osteichthyes Class Actinopterygii Class Sarcopterygii Superclass Tetrapoda Class Amphibia Class Sauropsida Class Synapsida Craniates, one of the three subdivisions of chordates, all have distinct skulls.
They include the hagfish. Michael J. Benton commented that "craniates are characterized by their heads, just as chordates, or all deuterostomes, are by their tails". Most craniates are vertebrates; these consist of a series of bony or cartilaginous cylindrical vertebrae with neural arches that protect the spinal cord, with projections that link the vertebrae. However hagfish have incomplete braincases and no vertebrae, are therefore not regarded as vertebrates, but as members of the craniates, the group from which vertebrates are thought to have evolved; however the cladistic exclusion of hagfish from the vertebrates is controversial, as they ma
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more they represent problematic species concepts. For example, the boundaries between related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, in a ring species. Among organisms that reproduce only asexually, the concept of a reproductive species breaks down, each clone is a microspecies. All species are given a two-part name, a "binomial"; the first part of a binomial is the genus.
The second part is called the specific epithet. For example, Boa constrictor is one of four species of the genus Boa. None of these is satisfactory definitions, but scientists and conservationists need a species definition which allows them to work, regardless of the theoretical difficulties. If species were fixed and distinct from one another, there would be no problem, but evolutionary processes cause species to change continually, to grade into one another. Species were seen from the time of Aristotle until the 18th century as fixed kinds that could be arranged in a hierarchy, the great chain of being. In the 19th century, biologists grasped. Charles Darwin's 1859 book The Origin of Species explained how species could arise by natural selection; that understanding was extended in the 20th century through genetics and population ecology. Genetic variability arises from mutations and recombination, while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures.
Genes can sometimes be exchanged between species by horizontal gene transfer. Viruses are a special case, driven by a balance of mutation and selection, can be treated as quasispecies. Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics. Early taxonomists such as Linnaeus had no option but to describe what they saw: this was formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts, is hard or impossible to test. Biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: agamospecies for asexual organisms biospecies for reproductively isolated sexual organisms ecospecies based on ecological niches evolutionary species based on lineage genetic species based on gene pool morphospecies based on form or phenotype and taxonomic species, a species as determined by a taxonomist.
A typological species is a group of organisms in which individuals conform to certain fixed properties, so that pre-literate people recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens would differentiate the species; this method was used as a "classical" method of determining species, such as with Linnaeus early in evolutionary theory. However, different phenotypes are not different species. Species named in this manner are called morphospecies. In the 1970s, Robert R. Sokal, Theodore J. Crovello and Peter Sneath proposed a variation on this, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms, it differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species is a group of sexually reproducing organisms that recognize one another as potential mates.
Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms. A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology, genes can move even between distantly related bacteria extending to the whole bacterial domain; as a rule of thumb, microbiologists have assumed that kinds of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA-DNA hybridisation to decide if they belong to the same species or not. This concept was narrowed in 2006 to a similarity of 98.7%. DNA-DNA hybri
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement and number of teeth in a given species at a given age; that is, the number and morpho-physiology of the teeth of an animal. Animals whose teeth are all of the same type, such as most non-mammalian vertebrates, are said to have homodont dentition, whereas those whose teeth differ morphologically are said to have heterodont dentition; the dentition of animals with two successions of teeth is referred to as diphyodont, while the dentition of animals with only one set of teeth throughout life is monophyodont. The dentition of animals in which the teeth are continuously discarded and replaced throughout life is termed polyphyodont; the dentition of animals in which the teeth are set in sockets in the jawbones is termed thecodont. The evolutionary origin of the vertebrate dentition remains contentious. Current theories suggest either an "outside-in" or "inside-out" evolutionary origin to teeth, with the dentition arising from odontodes on the skin surface moving into the mouth, or vice versa.
Despite this debate, it is accepted that vertebrate teeth are homologous to the dermal denticles found on the skin of basal Gnathostomes. Since the origin of teeth some 450mya, the vertebrate dentition has diversified within the reptiles and fish: however most of these groups continue to possess a long row of pointed or sharp-sided, undifferentiated teeth that are replaceable; the mammalian pattern is different. The teeth in the upper and lower jaws in mammals have evolved a close-fitting relationship such that they operate together as a unit. "They'occlude'", that is, the chewing surfaces of the teeth are so constructed that the upper and lower teeth are able to fit together, crushing, grinding or tearing the food caught between."All mammals except the monotremes, the xenarthrans, the pangolins, the cetaceans have up to four distinct types of teeth, with a maximum number for each. These are the incisor, the canine, the premolar, the molar; the incisors occupy the front of the tooth row in lower jaws.
They are flat, chisel-shaped teeth that meet in an edge-to-edge bite. Their function is cutting, slicing, or gnawing food into manageable pieces that fit into the mouth for further chewing; the canines are behind the incisors. In many mammals, the canines are pointed, tusk-shaped teeth, projecting beyond the level of the other teeth. In carnivores, they are offensive weapons for bringing down prey. In other mammals such as some primates, they are used to split open hard surfaced food; the premolars and molars are at the back of the mouth. Depending on the particular mammal and its diet, these two kinds of teeth prepare pieces of food to be swallowed by grinding, shearing, or crushing; the specialised teeth—incisors, canines and molars—are found in the same order in every mammal. In many mammals the infants have a set of teeth that are replaced by adult teeth; these are called primary teeth, baby teeth or milk teeth. Animals that have two sets of teeth, one followed by the other, are said to be diphyodont.
The dental formula for milk teeth is the same as for adult teeth except that the molars are missing. Because every mammal's teeth are specialised for different functions, many mammal groups have lost teeth not needed in their adaptation. Tooth form has undergone evolutionary modification as a result of natural selection for specialised feeding or other adaptations. Over time, different mammal groups have evolved distinct dental features, both in the number and type of teeth, in the shape and size of the chewing surface; the number of teeth of each type is written as a dental formula for one side of the mouth, or quadrant, with the upper and lower teeth shown on separate rows. The number of teeth in a mouth is twice that listed. In each set, incisors are indicated first, canines second, premolars third, molars, giving I:C:P:M. So for example, the formula 220.127.116.11 for upper teeth indicates 2 incisors, 1 canine, 2 premolars, 3 molars on one side of the upper mouth. The deciduous dental formula is notated in lowercase lettering preceded by the letter d: for example: di:dc:dp.
An animal's dentition for either deciduous or permanent teeth can thus be expressed as a dental formula, written in the form of a fraction, which can be written as I. C. P. MI. C. P. M, or I. C. P. M / I. C. P. M. For example, the following formulae show the deciduous and usual permanent dentition of all catarrhine primates, including humans: Deciduous: / × 2 = 20; this can be written as di2.dc1.dm2di2.dc1.dm2. Superscript and subscript denote upper and lower jaw, i.e. do not indicate mathematical operations. The dashes in the formula are not mathematical operators, but spacers.'d' denotes deciduous teeth. Another annotation is 18.104.22.168.1.0.2, if the fact that it pertains to deciduous teeth is stated, per examples found in some texts such as The Ca
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