Mammals are vertebrate animals constituting the class Mammalia, characterized by the presence of mammary glands which in females produce milk for feeding their young, a neocortex, fur or hair, three middle ear bones. These characteristics distinguish them from reptiles and birds, from which they diverged in the late Triassic, 201–227 million years ago. There are around 5,450 species of mammals; the largest orders are the rodents and Soricomorpha. The next three are the Primates, the Cetartiodactyla, the Carnivora. In cladistics, which reflect evolution, mammals are classified as endothermic amniotes, they are the only living Synapsida. The early synapsid mammalian ancestors were sphenacodont pelycosaurs, a group that produced the non-mammalian Dimetrodon. At the end of the Carboniferous period around 300 million years ago, this group diverged from the sauropsid line that led to today's reptiles and birds; the line following the stem group Sphenacodontia split off several diverse groups of non-mammalian synapsids—sometimes referred to as mammal-like reptiles—before giving rise to the proto-mammals in the early Mesozoic era.
The modern mammalian orders arose in the Paleogene and Neogene periods of the Cenozoic era, after the extinction of non-avian dinosaurs, have been among the dominant terrestrial animal groups from 66 million years ago to the present. The basic body type is quadruped, most mammals use their four extremities for terrestrial locomotion. Mammals range in size from the 30–40 mm bumblebee bat to the 30-meter blue whale—the largest animal on the planet. Maximum lifespan varies from two years for the shrew to 211 years for the bowhead whale. All modern mammals give birth to live young, except the five species of monotremes, which are egg-laying mammals; the most species-rich group of mammals, the cohort called placentals, have a placenta, which enables the feeding of the fetus during gestation. Most mammals are intelligent, with some possessing large brains, self-awareness, tool use. Mammals can communicate and vocalize in several different ways, including the production of ultrasound, scent-marking, alarm signals and echolocation.
Mammals can organize themselves into fission-fusion societies and hierarchies—but can be solitary and territorial. Most mammals are polygynous. Domestication of many types of mammals by humans played a major role in the Neolithic revolution, resulted in farming replacing hunting and gathering as the primary source of food for humans; this led to a major restructuring of human societies from nomadic to sedentary, with more co-operation among larger and larger groups, the development of the first civilizations. Domesticated mammals provided, continue to provide, power for transport and agriculture, as well as food and leather. Mammals are hunted and raced for sport, are used as model organisms in science. Mammals have been depicted in art since Palaeolithic times, appear in literature, film and religion. Decline in numbers and extinction of many mammals is driven by human poaching and habitat destruction deforestation. Mammal classification has been through several iterations since Carl Linnaeus defined the class.
No classification system is universally accepted. George Gaylord Simpson's "Principles of Classification and a Classification of Mammals" provides systematics of mammal origins and relationships that were universally taught until the end of the 20th century. Since Simpson's classification, the paleontological record has been recalibrated, the intervening years have seen much debate and progress concerning the theoretical underpinnings of systematization itself through the new concept of cladistics. Though field work made Simpson's classification outdated, it remains the closest thing to an official classification of mammals. Most mammals, including the six most species-rich orders, belong to the placental group; the three largest orders in numbers of species are Rodentia: mice, porcupines, beavers and other gnawing mammals. The next three biggest orders, depending on the biological classification scheme used, are the Primates including the apes and lemurs. According to Mammal Species of the World, 5,416 species were identified in 2006.
These were grouped into 153 families and 29 orders. In 2008, the International Union for Conservation of Nature completed a five-year Global Mammal Assessment for its IUCN Red List, which counted 5,488 species. According to a research published in the Journal of Mammalogy in 2018, the number of recognized mammal species is 6,495 species included 96 extinct; the word "mammal" is modern, from the scientific name Mammalia coined by Carl Linnaeus in 1758, derived from the Latin mamma. In an influential 1988 paper, Timothy Rowe defined Mammalia phylogenetically as the crown group of mammals, the clade consisting of the most recent common ancestor of living monotremes and therian m
Kansas is a U. S. state in the Midwestern United States. Its capital is Topeka and its largest city is Wichita, with its most populated county being Johnson County. Kansas is bordered by Nebraska on the north. Kansas is named after the Kansa Native American tribe; the tribe's name is said to mean "people of the wind" although this was not the term's original meaning. For thousands of years, what is now Kansas was home to diverse Native American tribes. Tribes in the eastern part of the state lived in villages along the river valleys. Tribes in the western part of the state were semi-nomadic and hunted large herds of bison. Kansas was first settled by European Americans in 1827 with the establishment of Fort Leavenworth; the pace of settlement accelerated in the 1850s, in the midst of political wars over the slavery debate. When it was opened to settlement by the U. S. government in 1854 with the Kansas–Nebraska Act, abolitionist Free-Staters from New England and pro-slavery settlers from neighboring Missouri rushed to the territory to determine whether Kansas would become a free state or a slave state.
Thus, the area was a hotbed of violence and chaos in its early days as these forces collided, was known as Bleeding Kansas. The abolitionists prevailed, on January 29, 1861, Kansas entered the Union as a free state. By 2015, Kansas was one of the most productive agricultural states, producing high yields of wheat, corn and soybeans. Kansas, which has an area of 82,278 square miles is the 15th-largest state by area and is the 34th most-populous of the 50 states with a population of 2,911,505. Residents of Kansas are called Kansans. Mount Sunflower is Kansas's highest point at 4,041 feet. For a millennium, the land, Kansas was inhabited by Native Americans; the first European to set foot in present-day Kansas was the Spanish conquistador Francisco Vázquez de Coronado, who explored the area in 1541. In 1803, most of modern Kansas was acquired by the United States as part of the Louisiana Purchase. Southwest Kansas, was still a part of Spain and the Republic of Texas until the conclusion of the Mexican–American War in 1848, when these lands were ceded to the United States.
From 1812 to 1821, Kansas was part of the Missouri Territory. The Santa Fe Trail traversed Kansas from 1821 to 1880, transporting manufactured goods from Missouri and silver and furs from Santa Fe, New Mexico. Wagon ruts from the trail are still visible in the prairie today. In 1827, Fort Leavenworth became the first permanent settlement of white Americans in the future state; the Kansas–Nebraska Act became law on May 30, 1854, establishing Nebraska Territory and Kansas Territory, opening the area to broader settlement by whites. Kansas Territory stretched all the way to the Continental Divide and included the sites of present-day Denver, Colorado Springs, Pueblo. Missouri and Arkansas sent settlers into Kansas all along its eastern border; these settlers attempted to sway votes in favor of slavery. The secondary settlement of Americans in Kansas Territory were abolitionists from Massachusetts and other Free-Staters, who attempted to stop the spread of slavery from neighboring Missouri. Directly presaging the American Civil War, these forces collided, entering into skirmishes that earned the territory the name of Bleeding Kansas.
Kansas was admitted to the Union as a free state on January 29, 1861, making it the 34th state to join the United States. By that time the violence in Kansas had subsided, but during the Civil War, on August 21, 1863, William Quantrill led several hundred men on a raid into Lawrence, destroying much of the city and killing nearly 200 people, he was roundly condemned by both the conventional Confederate military and the partisan rangers commissioned by the Missouri legislature. His application to that body for a commission was flatly rejected due to his pre-war criminal record. After the Civil War, many veterans constructed homesteads in Kansas. Many African Americans looked to Kansas as the land of "John Brown" and, led by freedmen like Benjamin "Pap" Singleton, began establishing black colonies in the state. Leaving southern states in the late 1870s because of increasing discrimination, they became known as Exodusters. At the same time, the Chisholm Trail was opened and the Wild West-era commenced in Kansas.
Wild Bill Hickok was a marshal at Hays and Abilene. Dodge City was another wild cowboy town, both Bat Masterson and Wyatt Earp worked as lawmen in the town. In one year alone, eight million head of cattle from Texas boarded trains in Dodge City bound for the East, earning Dodge the nickname "Queen of the Cowtowns." In response to demands of Methodists and other evangelical Protestants, in 1881 Kansas became the first U. S. state to adopt a constitutional amendment prohibiting all alcoholic beverages, repealed in 1948. Kansas is bordered by Nebraska on the north; the state is divided into 105 counties with 628 cities, is located equidistant from the Pacific and Atlantic oceans. The geographic center of the 48 contiguous states is in Smith County near Lebanon; until 1989, the Meades Ranch Triangulation Station in Osborne County was the geodetic center of North America: the central reference point for all maps of North America. The geographic center of Kansas is in Barton County. Kansas is underlain by a sequence of horizontal to westward dipping sedimentary rocks.
A sequence of Mississippian and Permian rocks outcrop in the eastern and southern part of the state
An endangered species is a species, categorized as likely to become extinct. Endangered, as categorized by the International Union for Conservation of Nature Red List, is the second most severe conservation status for wild populations in the IUCN's schema after Critically Endangered. In 2012, the IUCN Red List featured 3,079 animal and 2,655 plant species as endangered worldwide; the figures for 1998 were 1,102 and 1,197. Many nations have laws that protect conservation-reliant species: for example, forbidding hunting, restricting land development or creating preserves. Population numbers and species' conservation status can be found at the lists of organisms by population; the conservation status of a species indicates the likelihood. Many factors are considered; the IUCN Red List of Threatened Species is the best-known worldwide conservation status listing and ranking system. Over 50% of the world's species are estimated to be at risk of extinction. Internationally, 199 countries have signed an accord to create Biodiversity Action Plans that will protect endangered and other threatened species.
In the United States, such plans are called Species Recovery Plans. Though labelled a list, the IUCN Red List is a system of assessing the global conservation status of species that includes "Data Deficient" species – species for which more data and assessment is required before their status may be determined – as well species comprehensively assessed by the IUCN's species assessment process; those species of "Near Threatened" and "Least Concern" status have been assessed and found to have robust and healthy populations, though these may be in decline. Unlike their more general use elsewhere, the List uses the terms "endangered species" and "threatened species" with particular meanings: "Endangered" species lie between "Vulnerable" and "Critically Endangered" species, while "Threatened" species are those species determined to be Vulnerable, Endangered or Critically Endangered; the IUCN categories, with examples of animals classified by them, include: Extinct no remaining individuals of the species Extinct in the wild Captive individuals survive, but there is no free-living, natural population.
Critically endangered Faces an high risk of extinction in the immediate future. Endangered Faces a high risk of extinction in the near future. Vulnerable Faces a high risk of endangerment in the medium term. Near-threatened May be considered threatened in the near future. Least concern No immediate threat to species' survival. A) Reduction in population size based on any of the following: An observed, inferred or suspected population size reduction of ≥ 70% over the last 10 years or three generations, whichever is the longer, where the causes of the reduction are reversible AND understood AND ceased, based on any of the following: direct observation an index of abundance appropriate for the taxon a decline in area of occupancy, extent of occurrence or quality of habitat actual or potential levels of exploitation the effects of introduced taxa, pathogens, competitors or parasites. An observed, inferred or suspected population size reduction of ≥ 50% over the last 10 years or three generations, whichever is the longer, where the reduction or its causes may not have ceased OR may not be understood OR may not be reversible, based on any of to under A1.
A population size reduction of ≥ 50%, projected or suspected to be met within the next 10 years or three generations, whichever is the longer, based on any of to under A1. An observed, inferred, projected or suspected population size reduction of ≥ 50% over any 10 year or three generation period, whichever is longer, where the time period must include both the past and the future, where the reduction or its causes may not have ceased OR may not be understood OR may not be reversible, based on any of to under A1. B) Geographic range in the form of either B1 OR B2 OR both: Extent of occurrence estimated to be less than 5,000 km², estimates indicating at least two of a-c: Severely fragmented or known to exist at no more than five locations. Continuing decline, observed or projected, in any of the following: extent of occurrence area of occupancy area, extent or quality of habitat number of locations or subpopulations number of mature individuals Extreme fluctuations in any of the following: extent of occurrence area of occupancy number of locations or subpopulations number of mature individuals Area of occupancy estimated to be less than 500 km², estimates indicating at least two of a-c: Severely fragmented or known to exist at no more than five locations.
Continuing decline, observed or projected, in any of the following: extent of occurrence area of occupancy area, extent or quality of habitat number of locations or subpopulations number of mature individuals Extreme fluctuations in any of the following: extent of occurrence area of occupancy number of locations or subpopulations number of mature individualsC) Population estimated to number fewer than 2,500 mature individuals and either: An estimated continuing decline of at least 20% within five years or two generations, whichever is longer, OR A continuing decline, projected
In evolutionary biology, parasitism is a relationship between species, where one organism, the parasite, lives on or in another organism, the host, causing it some harm, is adapted structurally to this way of life. The entomologist E. O. Wilson has characterised parasites as "predators that eat prey in units of less than one". Parasites include protozoans such as the agents of malaria, sleeping sickness, amoebic dysentery. There are six major parasitic strategies of exploitation of animal hosts, namely parasitic castration, directly transmitted parasitism, trophically transmitted parasitism, vector-transmitted parasitism and micropredation. Like predation, parasitism is a type of consumer-resource interaction, but unlike predators, with the exception of parasitoids, are much smaller than their hosts, do not kill them, live in or on their hosts for an extended period. Parasites of animals are specialised, reproduce at a faster rate than their hosts. Classic examples include interactions between vertebrate hosts and tapeworms, the malaria-causing Plasmodium species, fleas.
Parasites reduce host fitness by general or specialised pathology, from parasitic castration to modification of host behaviour. Parasites increase their own fitness by exploiting hosts for resources necessary for their survival, in particular by feeding on them and by using intermediate hosts to assist in their transmission from one definitive host to another. Although parasitism is unambiguous, it is part of a spectrum of interactions between species, grading via parasitoidism into predation, through evolution into mutualism, in some fungi, shading into being saprophytic. People have known about parasites such as roundworms and tapeworms since ancient Egypt and Rome. In Early Modern times, Antonie van Leeuwenhoek observed Giardia lamblia in his microscope in 1681, while Francesco Redi described internal and external parasites including sheep liver fluke and ticks. Modern parasitology developed in the 19th century. In human culture, parasitism has negative connotations; these were exploited to satirical effect in Jonathan Swift's 1733 poem "On Poetry: A Rhapsody", comparing poets to hyperparasitical "vermin".
In fiction, Bram Stoker's 1897 Gothic horror novel Dracula and its many adaptations featured a blood-drinking parasite. Ridley Scott's 1979 film Alien was one of many works of science fiction to feature a terrifying parasitic alien species. First used in English in 1539, the word parasite comes from the Medieval French parasite, from the Latin parasitus, the latinisation of the Greek παράσιτος, "one who eats at the table of another" and that from παρά, "beside, by" + σῖτος, "wheat", hence "food"; the related term parasitism appears in English from 1611. Parasitism is a kind of symbiosis, a close and persistent long-term biological interaction between a parasite and its host. Unlike commensalism and mutualism, the parasitic relationship harms the host, either feeding on it or, as in the case of intestinal parasites, consuming some of its food; because parasites interact with other species, they can act as vectors of pathogens, causing disease. Predation is by definition not a symbiosis, as the interaction is brief, but the entomologist E. O. Wilson has characterised parasites as "predators that eat prey in units of less than one".
Within that scope are many possible strategies. Taxonomists classify parasites in a variety of overlapping schemes, based on their interactions with their hosts and on their life-cycles, which are sometimes complex. An obligate parasite depends on the host to complete its life cycle, while a facultative parasite does not. Parasite life-cycles involving only one host are called "direct". An endoparasite lives inside the host's body. Mesoparasites - like some copepods, for example - enter an opening in the host's body and remain embedded there; some parasites can be generalists, feeding on a wide range of hosts, but many parasites, the majority of protozoans and helminths that parasitise animals, are specialists and host-specific. An early basic, functional division of parasites distinguished macroparasites; these each had a mathematical model assigned in order to analyse the population movements of the host–parasite groupings. The microorganisms and viruses that can reproduce and complete their life cycle within the host are known as microparasites.
Macroparasites are the multicellular organisms that reproduce and complete their life cycle outside of the host or on the host's body. Much of the thinking on types of parasitism has focussed on terrestrial animal parasites of animals, such as helminths; those in other environments and with other hosts have analogous strategies. For example, the snubnosed eel is a facultative endoparasite that opportunistically burrows into and eats sick and dying fish. Plant-eating insects such as scale insects and caterpillars resemble ectoparasites, attacking much larger plants; as female scale-insects cannot move, they are obligate parasites, permanently attached to their hosts. There are six major parasitic strategies, namely parasitic castration, directly transmitted parasitism, trophically transmitted parasitism, vector-transmitted parasitism, parasitoid
Manitoba is a province at the longitudinal centre of Canada. It is considered one of the three prairie provinces and is Canada's fifth-most populous province with its estimated 1.3 million people. Manitoba covers 649,950 square kilometres with a varied landscape, stretching from the northern oceanic coastline to the southern border with the United States; the province is bordered by the provinces of Ontario to the east and Saskatchewan to the west, the territories of Nunavut to the north, Northwest Territories to the northwest, the U. S. states of North Minnesota to the south. Aboriginal peoples have inhabited. In the late 17th century, fur traders arrived on two major river systems, what is now called the Nelson in northern Manitoba and in the southeast along the Winnipeg River system. A Royal Charter in 1670 granted all the lands draining into Hudson's Bay to the British company and they administered trade in what was called Rupert's Land. During the next 200 years, communities continued to grow and evolve, with a significant settlement of Michif in what is now Winnipeg.
The assertion of Métis identity and self-rule culminated in negotiations for the creation of the province of Manitoba. There are many factors that led to an armed uprising of the Métis people against the Government of Canada, a conflict known as the Red River Rebellion aka Resistance; the resolution of the assertion of the right to representation led to the Parliament of Canada passing the Manitoba Act in 1870 that created the province. Manitoba's capital and largest city, Winnipeg, is the eighth-largest census metropolitan area in Canada. Other census agglomerations in the province are Brandon, Portage la Prairie, Thompson; the name Manitoba is believed to be derived from the Ojibwe or Assiniboine languages. The name derives from Cree manitou-wapow or Ojibwa manidoobaa, both meaning "straits of Manitou, the Great Spirit", a place referring to what are now called The Narrows in the centre of Lake Manitoba, it may be from the Assiniboine for "Lake of the Prairie". The lake was known to French explorers as Lac des Prairies.
Thomas Spence chose the name to refer to a new republic he proposed for the area south of the lake. Métis leader Louis Riel chose the name, it was accepted in Ottawa under the Manitoba Act of 1870. Manitoba is bordered by the provinces of Ontario to the east and Saskatchewan to the west, the territories of Nunavut to the north, the US states of North Dakota and Minnesota to the south; the province meets the Northwest Territories at the four corners quadripoint to the extreme northwest, though surveys have not been completed and laws are unclear about the exact location of the Nunavut–NWT boundary. Manitoba adjoins Hudson Bay to the northeast, is the only prairie province to have a saltwater coastline; the Port of Churchill is Canada's only Arctic deep-water port. Lake Winnipeg is the tenth-largest freshwater lake in the world. Hudson Bay is the world's second-largest bay by area. Manitoba is at the heart of the giant Hudson Bay watershed, once known as Rupert's Land, it was a vital area of the Hudson's Bay Company, with many rivers and lakes that provided excellent opportunities for the lucrative fur trade.
The province has a saltwater coastline bordering Hudson Bay and more than 110,000 lakes, covering 15.6 percent or 101,593 square kilometres of its surface area. Manitoba's major lakes are Lake Manitoba, Lake Winnipegosis, Lake Winnipeg, the tenth-largest freshwater lake in the world; some traditional Native lands and boreal forest on Lake Winnipeg's east side are a proposed UNESCO World Heritage Site. Manitoba is at the centre of the Hudson Bay drainage basin, with a high volume of the water draining into Lake Winnipeg and north down the Nelson River into Hudson Bay; this basin's rivers reach far west to the mountains, far south into the United States, east into Ontario. Major watercourses include the Red, Nelson, Hayes and Churchill rivers. Most of Manitoba's inhabited south has developed in the prehistoric bed of Glacial Lake Agassiz; this region the Red River Valley, is flat and fertile. Baldy Mountain is the province's highest point at 832 metres above sea level, the Hudson Bay coast is the lowest at sea level.
Riding Mountain, the Pembina Hills, Sandilands Provincial Forest, the Canadian Shield are upland regions. Much of the province's sparsely inhabited north and east lie on the irregular granite Canadian Shield, including Whiteshell and Nopiming Provincial Parks. Extensive agriculture is found only in the province's southern areas, although there is grain farming in the Carrot Valley Region; the most common agricultural activity is cattle husbandry, followed by assorted grains and oilseed. Around 12 percent of Canada's farmland is in Manitoba. Manitoba has an extreme continental climate. Temperatures and precipitation decrease from south to north and increase from east to west. Manitoba is far from the moderating large bodies of water; because of the flat landscape, it is exposed to cold Arctic high-pressure air masses from the northwest during January and February. In the summer, air masses sometimes come out of the Southern United States, as warm humid air is drawn northward from the Gulf of Mexico.
Temperatures exceed 30 °C numerous times each summer, the combination of heat and humidity can bring the humidex value to the mid-40s. Carman, Manitoba recorded the second-highest humidex in Canada in 2007, with
The kit fox is a fox species of North America. Its range is in the Southwestern United States and northern and central Mexico; some mammalogists classify it as conspecific with the swift fox, V. velox, but molecular systematics imply that the two species are distinct. The northernmost part of its range is the arid interior of Oregon, its eastern limit is southwestern Colorado. It can be found south through Nevada, southeastern California, New Mexico, into western Texas; the endangered San Joaquin kit fox was very common in the San Joaquin Valley and through much of Central California. Its 1990 population was estimated to be 7,000; this subspecies is still endangered, after nearly 50 years of being on the Endangered Species List. This subspecies was listed March 3, 1967. On September 26, 2007, Wildlands Inc. announced the designation of the 684 acre Deadman a Creek Conservation Bank, intended to protect habitat of the San Joaquin kit fox. However, the population continues to decline due to heavy habitat loss.
Other factors include competition from red fox, the extermination of the gray wolf from California has left the coyote as the dominant meso-predator in kit fox territory bringing an imbalance in ecosystem relationships. The kit fox is the smallest species of the family Canidae found in North America It has large ears, between 71 and 95 mm, that help the fox lower its body temperature and give it exceptional hearing; this species exhibits sexual dimorphism, with the male being larger. The average species weight is between 2.7 kg. The body length is 455 to 535 mm; the tail adds another 250–340 mm to its length. It has a gray coat, with rusty tones, a black tip to its tail. Unlike the gray fox, it has no stripe along the length of its tail, its color ranges from yellowish to gray, the back is darker than the majority of its coat. It has distinct dark patches around the nose; the kit fox is a nocturnal animal, but sometimes ventures out of its den during the day. It goes out to hunt shortly after sunset eating small animals such as kangaroo rats, cottontail rabbits, black-tailed jackrabbits, meadow voles, prairie dogs, lizards, snakes and ground-dwelling birds.
It will scavenge carrion. While carnivorous, if food is scarce, it has been known to eat tomatoes, cactus fruits and other fruits. Different kit fox families can occupy the same hunting grounds, but do not go hunting at the same time; the Kit Fox experiences a interesting, but rare, tooth malformation that causes Bigeminy: a heart rhythm problem. This is caused by the fusion of a maxillary third premolar tooth and an adjoining supernumerary tooth which makes a single tooth with two cusps and three roots. Kit foxes favor arid climates, such as desert scrub and grasslands. Good examples of common habitats are sagebrush Artemisia tridentata and saltbrush Atriplex polycarpa, they can be found in agricultural areas, too. They are found at elevations of 400 to 1,900 meters above sea level; the kit fox is a monogamous species. Male and female kit foxes establish monogamous mating pairs during October and November. Polygamous mating relationships have been observed. Pairs can change year to year, they mate from December to February.
Litters are born throughout March and April containing one to seven pups, average four pups. The gestation is 49 to 55 days. Pups do not leave the den, they are become independent at five to six months old. They become sexually mature at 10 months. Both parents take part in protecting their young; the average lifespan of a wild kit fox is 5.5 years. In captivity, they can live 12 years. One Californian study of 144 kit fox pups showed a 74% mortality rate in pups within the first year. 10. Vieira, J. L. & Có, M. A.. Dental and Temporomandibular Joint Pathology of the Kit Fox Author links open overlay panel. Eletrônica De Potência,2, 35-42. Doi:10.18618/rep.1997.1.035042 ARKive – images and movies of the kit fox NPS - information about Kit Fox in Joshua Tree National Park
The biological family Canidae is a lineage of carnivorans that includes domestic dogs, coyotes, jackals and many other extant and extinct dog-like mammals. A member of this family is called a canid; the cat-like feliformia and dog-like caniforms emerged within the Carnivoramorpha 43 million years before present. The caniforms included the fox-like genus Leptocyon whose various species existed from 34 million years ago before branching 11.9 Mya into Vulpi and Canidae. Canids are found on all continents except Antarctica, having arrived independently or accompanied human beings over extended periods of time. Canids vary in size from the 2-m-long gray wolf to the 24-cm-long fennec fox; the body forms of canids are similar having long muzzles, upright ears, teeth adapted for cracking bones and slicing flesh, long legs, bushy tails. They are social animals, living together in family units or small groups and behaving co-operatively. Only the dominant pair in a group breeds, a litter of young is reared annually in an underground den.
Canids communicate by scent vocalizations. They are intelligent. One canid, the domestic dog, long ago entered into a partnership with humans and today remains one of the most kept domestic animals. In the history of the carnivores, the family Canidae is represented by the two extinct subfamilies designated as Hesperocyoninae and Borophaginae, the extant subfamily Caninae; this subfamily includes their most recent fossil relatives. All living canids as a group form a dental monophyletic relationship with the extinct borophagines, with both groups having a bicuspid on the lower carnassial talonid, which gives this tooth an additional ability in mastication. This, together with the development of a distinct entoconid cusp and the broadening of the talonid of the first lower molar, the corresponding enlargement of the talon of the upper first molar and reduction of its parastyle distinguish these late Cenozoic canids and are the essential differences that identify their clade. Within the Canidae, the results of allozyme and chromosome analyses have suggested several phylogenetic divisions: The wolf-like canids include the domestic dog, gray wolf, red wolf, eastern wolf, Eurasian golden jackal, African golden wolf, Ethiopian wolf, black-backed jackal, side-striped jackal and African wild dog.
The fox-like canids include the kit fox, red fox, Cape fox, Arctic fox, fennec fox. The South American canids include the bush dog, hoary fox, crab-eating fox, maned wolf. Various monotypic taxa include the bat-eared fox, gray fox, raccoon dog. DNA analysis shows; the wolf-like canids and the South American canids together form the tribe Canini. Molecular data imply a North American origin of living Canidae some 10 Mya and an African origin of wolf-like canines, with the jackals being the most basal of this group; the South American clade is rooted by the maned wolf and bush dog, the fox-like canids by the fennec fox and Blanford's fox. The gray fox and island fox are basal to the other clades; the cladogram below is based on the phylogeny of Lindblad-Toh et al. modified to incorporate recent findings on Canis, Vulpes and Dusicyon species. The Canidae today include a diverse group of some 34 species ranging in size from the maned wolf with its long limbs to the short-legged bush dog. Modern canids inhabit forests, tundra and deserts throughout tropical and temperate parts of the world.
The evolutionary relationships between the species have been studied in the past using morphological approaches, but more molecular studies have enabled the investigation of phylogenetic relationships. In some species, genetic divergence has been suppressed by the high level of gene flow between different populations and where the species have hybridized, large hybrid zones exist. Carnivorans evolved from miacoids about 55 Mya during the late Paleocene; some 5 million years the carnivorans split into two main divisions: caniforms and feliforms. By 40 Mya, the first member of the dog family proper had arisen. Called Prohesperocyon wilsoni, its fossilized remains have been found in what is now the southwestern part of Texas; the chief features which identify it as a canid include the loss of the upper third molar, the structure of the middle ear which has an enlarged bulla. Prohesperocyon had longer limbs than its predecessors, had parallel and touching toes which differ markedly from the splayed arrangements of the digits in bears.
The canid family soon subdivided into three subfamilies, each of which diverged during the Eocene: Hesperocyoninae and Caninae. The Caninae are the only surviving subfamily and all present-day canids, including wolves, coyotes and domestic dogs, belong to it. Members of each subfamily showed an increase in body mass with time and some ex