In the sequence of cultural stages first proposed for the archaeology of the Americas by Gordon Willey and Philip Phillips in 1958, the Lithic stage was the earliest period of human occupation in the Americas, as post-glacial hunters and collectors spread through the Americas. The stage derived its name from the first appearance of Lithic flaked stone tools; the term Paleo-Indian is an alternative indicating much the same period. This stage was conceived of as embracing two major categories of stone technology: unspecialized and unformulated core and flake industries, with percussion the dominant and only technique employed, industries exhibiting more advanced "blade" techniques of stoneworking, with specialized fluted or unfluted lanceolate points the most characteristic artifact types. Throughout South America, there are stone tool traditions of the lithic stage, such as the "fluted fishtail" that reflect localized adaptations to the diverse habitats of the continent; the indications and timing of the end of the Lithic stage vary between regions.
The use of textiles, fired pottery and start of the gradual replacement of hunter gatherer lifestyles with the use of agriculture and domesticated animals would all be factors. End dates are around 5,000 to 3,000 BC in many areas; the Archaic stage is the most used term for the succeeding stage, but in the periodization of pre-Columbian Peru the Cotton Pre-Ceramic may be used, as in the Norte Chico civilization cultivated cotton seems to have been important in economic and power relations, from around 3,200 BC. One of the leading figures is Alex Krieger who has documented hundreds of sites that have yielded crude, percussion-flaked tools; the most convincing evidence for a lithic stage is based upon data recovered from sites in South America where such crude tools have been found and dated to more than 20,000 years ago. In North America, the time encompasses the Paleo-Indian period that subsequently is divided into more specific time terms such as Early Lithic stage or Early Paleo-Indians and Middle Paleo-Indians or Middle Lithic stage.
Examples include the Clovis culture and Folsom tradition groups. The Lithic stage was followed by the Archaic stage. 12,340 BCE–10,800 BCE: a stone-lined hearth and coprolites left in Paisley Caves, Oregon 10,200 BCE: Cooper Bison skull is painted with a red zigzag in present-day Oklahoma, becoming the oldest known painted object in North America. 9500 BC: Cordilleran and Laurentide ice sheets retreat enough to open a habitable ice-free corridor through Canada along the eastern flank of the Rocky Mountains. 9500 BC: People craft early Clovis spear points and skin scrapers from rock in New Mexico. 9250–8950 BC: Clovis points - thin, fluted projectile points created using bifacial percussion flaking - are created by Clovis culture peoples in the Plains and Southwestern North America 9001 BC: Archaeological materials found on the Channel Islands of California and in coastal Peru. 9000 BC: Archaeological materials found on Channel Islands off the California coast 9000 BC: Human settlers arrive in the Great Basin with its cool, wet prevailing climate 9000–8900 BC: The Folsom culture in New Mexico leaves Bison bones and stone spear points.
8700 BC: Human settlement reaches the Northwestern Plateau region. 8000 BC: The last glacial ends, causing sea levels to rise and flood the Beringia land bridge, closing the primary migration route from Siberia. 8000 BC: Sufficient rain falls on the American Southwest to support many large mammal species--mammoth, a bison species-—that soon go extinct. 8000 BC: Native Americans leave documented traces of their presence in every habitable corner of the Americas, including the American Northeast, the Pacific Northwest, a cave on Prince of Wales Island in the Alexander archipelago of southeast Alaska following these game animals. 8000 BC: Hunters in the American Southwest both use the atlatl. 8000 BC: Sufficient rain falls on the American Southwest to support many large mammal species, such as mammoth, a bison species-—that soon go extinct. 8000 BC: Hunters in the American Southwest use the atlatl. Times from the 8000 BC to about 3000 BC may be classified as part of the lithic stage or of an archaic stage, depending on authority and on region.
7500 BC: Early basketry. 7560—7370 BC: Kennewick Man dies along the shore of the Columbia River in Washington State, leaving one of the most complete early Native American skeletons. 7000 BC: Northeastern peoples depend on deer and wild grains as the climate warms. 7000 BC: Native Americans in Lahontan Basin, Nevada mummify their dead to give them honor and respect, evidencing deep concern about their treatment and condition. 6500 BC–200 AD: The San Dieguito-Pinto tradition and Chihuahua Tradition flourish in southern California, the Southwest, northwestern Mexico. 6000 BC: Ancestors of Penutian-speaking peoples settle in the Northwestern Plateau. 6000 BC: Nomadic hunting bands roam Subarctic Alaska following herds of caribou and other game animals. 6000 BC: Aleuts begin to arrive in the Aleutian Islands. 5700 BC: Cataclysmic eruption of Mount Mazama in Oregon. 5500 BC–500 AD Oshara Tradition, a Southwestern Archaic Tradition, arises in north-central New Mexico, the San Juan Basin, the Rio Grande Valley, southern Colorado, southeastern Utah.
Natives of the Northwestern Plateau begin to rely on salmon runs. 5000 BC: Early cultivation of food crops began in Mesoamerica. 5000 BC: Native Americans in the Pacific Northwest from Alaska to California develop a fishing economy, with salmon as a staple. 5000 BC: The Old Copper Culture of the Great Lakes area hammers the metal into various tools and ornaments, such as knives, awls, bracelets and pendants. Archaeology of the Amer
Mogollon culture is an archaeological culture of Native American peoples from Southern New Mexico and Arizona, Northern Sonora and Chihuahua, Western Texas, a region known as Oasisamerica. The Mogollon culture is one of the major prehistoric Southwestern cultural divisions of the Southwestern United States and Northern Mexico; the culture flourished from the archaic period, c. 200 CE, to either 1450 or 1540 CE, when the Spanish arrived. The name Mogollon comes from the Mogollon Mountains, which were named after Don Juan Ignacio Flores Mogollón, Spanish Governor of New Spain from 1712 to 1715; the name was defined in 1936 by archaeologist Emil W. Haury; the distinct facets of Mogollon culture were recorded by Emil Haury, based on his excavations in 1931, 1933, 1934 at the Harris Village in Mimbres, New Mexico, the Mogollon Village on the upper San Francisco River in New Mexico Haury recognized differences between architecture and artifacts from these sites as compared with sites in the Hohokam archaeological culture area and the Ancestral Pueblo archaeological culture area.
Key differences included brown-paste, coil-and-scrape pottery excavated semi-subterranean pit-houses and different ceremonial architecture. Eight decades of subsequent research have confirmed Haury's initial findings. Today, the distinctiveness of the Mogollon pottery manufacture, architectural construction, ground-stone tool design and customs of residence location, mortuary treatment is recognized; the earliest Mogollon pithouses were deep and either oval-shaped. Over time, Mogollon people not as deep, their villages had kivas, or round, semi-subterranean ceremonial structures. Mogollon origins remain a matter of speculation. One model holds that the Mogollon emerged from a preceding Desert Archaic tradition that links Mogollon ancestry with the first prehistoric human occupations of the area. In this model, cultural distinctions emerged in the larger region when populations grew great enough to establish villages and larger communities. An alternative possibility holds that the Mogollon were descendants of early farmers who migrated from farming regions in central Mexico around 3500 BCE, who displaced descendants of the antecedent Desert Archaic peoples.
A third view is that at the time of the shift from hunting and gathering to agriculture the Cochise culture had been immigrants into the area about 5000 BCE, were not linked to the earlier inhabitants, but were receptive to cultural dissemination from the farmers of Central Mexico. The Mogollon were foragers who augmented their subsistence efforts by farming. Through the first millennium CE, dependence on farming increased. Water control features are common among Mimbres branch sites from the 10th through 12th centuries CE; the nature and density of Mogollon residential villages changed through time. The earliest Mogollon villages are small hamlets composed of several pithouses. Village sizes increased by the 11th century surface pueblos became common. Cliff-dwellings became common during 14th centuries. Research on Mogollon culture has led to the recognition of regional variants, of which the most recognized in popular media is the Mimbres culture. Others include the Jornada, Reserve, Point of Pines, San Simon, Upper Gila branches.
Although the Mimbres culture is the most well-known subset of the Mogollon archaeological culture-area, the entire Mogollon occupation spans a greater interval of time and a vastly larger area than is encompassed by the Mimbres culture. Mogollon culture is divided into five periods proposed by Joe Ben Wheat in 1955: Mogollon 1: Pine Lawn, Penasco, Circle Prairie, Hilltop phases Mogollon 2: San Lorenzo, Dos Cabezas, Circle Prairie, Cottonwood phases Mogollon 3: San Francisco, Galiuro and San Marcial phases Mogollon 4: Three Circle, Corduroy and Capitan phases Mogollon 5, including the Classic Mimbres phrase: Mangus, Encinas, Tularosa, Dona Anna, Three Rivers, El Paso, San Anders phases. An alternate way of viewing Mogollon culture is through three periods of housing types: Early Pithouse Late Pithouse Mogollon Pueblo. Archaeological sites attributed to the Mogollon culture are found in the Gila Wilderness, Mimbres River Valley, along the Upper Gila river and Hueco Tanks, an area of low mountains between the Franklin Mountains to the west and the Hueco Mountains to the east.
Gila Cliff Dwellings National Monument in southwestern New Mexico was established as a National Monument on 16 November 1907. It contains several archaeological sites attributed to the Mimbres branch. At the headwaters of the Gila, Mimbres populations adjoined another more northern branch of the Mogollon culture; the TJ Ruin, for example, is a Classic Mimbres phase pueblo, however the cliff dwellings are Tularosa phase. The Hueco Tanks State Historic Site is 32 mi northeast of El Paso, Texas. Mimbres may, depending on its context, refer to a tradition within a subregion of the Mogollon culture area or to an interva
Park County, Montana
Park County is a county located in the U. S. state of Montana. At the 2010 census, the population was 15,636, its county seat is Livingston. A small part of Yellowstone National Park is located in the extreme southern part of the county. Park County was authorized by the Territorial Legislature of Montana Territory on February 23, 1887, it was named for its proximity to Yellowstone National Park, a portion of, now included in County boundaries. This area had long been peopled and hunted by indigenous peoples, including members of the Crow and Blackfoot tribes; the first recorded visit of European-descent peoples was the Clark Expedition. Mountain man Jim Bridger wintered with Crow nomads near present-day Emigrant Hunting and trapping brought many men across this area during the first part of the nineteenth century, but by 1850 the beaver population had nearly disappeared. Gold was discovered in Emigrant Gulch in 1863, by 1864 a booming town was serving the area. In late 1864, Yellowstone City, consisting of 75 cabins, was in operation.
Two miners, John Bozeman and John Jacobs, laid out the Bozeman Trail in 1864 to allow access to western Montana Territory, it soon became a well-traveled path between Fort Laramie and western Montana. This road ran through the future Livingston area to Bozeman Pass. Much of this traffic did originate in Fort Laramie, but by the late 1860s a considerable traffic was arriving via the Yellowstone River, at an embarkation point in the Livingston area. By the late 1860s, the indigenous peoples, being denied access to their previous areas, had become a danger to the settlers, so Territorial Governor Smith organized a militia to guard the Livingston area; the group encamped at Fort Howie, near the mouth of Shields River, five miles east of present-day Livingston. In 1868 an Indian agency was established at Mission Creek. To service the fort, a ferry service was set up to cross the Yellowstone River, four miles east of present-day Livingston. Benson's Landing was the small settlement that grew around the landing, was a bustling community center for a few decades.
Interest in the Yellowstone Park area grew around 1870. By 1872, the federal government had established it as the nation's first. By 1880 the area of the future Park County contained some 200 souls. In 1881 the Northern Pacific Railway entered Montana Territory, extended a line to Livingston by November 22, 1882. In 1883 the National Park branch of the Northern Pacific was completed; the area population continued to grow rapidly. By 1890 the county population had reached 6,900. According to the US Census Bureau, the county has a total area of 2,813 square miles, of which 2,803 square miles is land and 10.4 square miles is water. The highest natural point in Montana, Granite Peak at 12,807 feet, is located in Park County; the county attained its present boundaries in 1978, when the former Yellowstone National Park county-equivalent was dissolved and apportioned between Gallatin County and Park County. Gallatin County received 99.155 square miles of land area and 0.119 square miles of water area, whereas Park County received 146.229 square miles of land area and 0.608 square miles of water area.
The geographies transferred are known now as Census Tract 14 in Gallatin County, as Census Tract 6 in Park County. Voters in Park County tend to support the Republican Party candidate in national elections. At the 2000 United States Census, there were 15,694 people, 6,828 households and 4,219 families in the county; the population density was 6 per square mile. There were 8,247 housing units at an average density of 3 per square mile; the racial makeup of the county was 96.65% White, 0.40% Black or African American, 0.92% Native American, 0.36% Asian, 0.03% Pacific Islander, 0.47% from other races, 1.17% from two or more races. 1.84% of the population were Hispanic or Latino of any race. 23.5% were of German, 12.4% English, 9.5% Norwegian, 9.0% Irish and 7.9% American ancestry. There were 6,828 households of which 28.10% had children under the age of 18 living with them, 51.00% were married couples living together, 7.30% had a female householder with no husband present, 38.20% were non-families.
32.40% of all households were made up of individuals and 11.70% had someone living alone, 65 years of age or older. The average household size was 2.27 and the average family size was 2.88. The population contained 23.5% under age 18, 6.50% 18–24, 27.90% 25–44, 27.10% 45–64, 14.90% who were 65+. The median age was 41 years. For every 100 females there were 97.40 males. For every 100 females age 18 and over, there were 96.10 males. The median household income was $31,739 and the median family income was $40,561. Males had a median income of $28,215 and females $19,973; the per capita income was $17,704. About 7.20% of families and 11.40% of the population were below the poverty line, including 13.10% of those under age 18 and 10.10% of those age 65 or over. As of the 2010 United States Census, there were 15,636 people, 7,310 households, 4,177 families residing in the county; the population density was 5.6 inhabitants per square mile. There were 9,375 housing units at an average density of 3.3 per square mile.
The racial makeup of the county was 96.5% white, 0.8% Am
Radiocarbon dating is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was developed in the late 1940s by Willard Libby, who received the Nobel Prize in Chemistry for his work in 1960, it is based on the fact that radiocarbon is being created in the atmosphere by the interaction of cosmic rays with atmospheric nitrogen. The resulting 14C combines with atmospheric oxygen to form radioactive carbon dioxide, incorporated into plants by photosynthesis; when the animal or plant dies, it stops exchanging carbon with its environment, from that point onwards the amount of 14C it contains begins to decrease as the 14C undergoes radioactive decay. Measuring the amount of 14C in a sample from a dead plant or animal such as a piece of wood or a fragment of bone provides information that can be used to calculate when the animal or plant died; the older a sample is, the less 14C there is to be detected, because the half-life of 14C is about 5,730 years, the oldest dates that can be reliably measured by this process date to around 50,000 years ago, although special preparation methods permit accurate analysis of older samples.
Research has been ongoing since the 1960s to determine what the proportion of 14C in the atmosphere has been over the past fifty thousand years. The resulting data, in the form of a calibration curve, is now used to convert a given measurement of radiocarbon in a sample into an estimate of the sample's calendar age. Other corrections must be made to account for the proportion of 14C in different types of organisms, the varying levels of 14C throughout the biosphere. Additional complications come from the burning of fossil fuels such as coal and oil, from the above-ground nuclear tests done in the 1950s and 1960s; because the time it takes to convert biological materials to fossil fuels is longer than the time it takes for its 14C to decay below detectable levels, fossil fuels contain no 14C, as a result there was a noticeable drop in the proportion of 14C in the atmosphere beginning in the late 19th century. Conversely, nuclear testing increased the amount of 14C in the atmosphere, which attained a maximum in about 1965 of twice what it had been before the testing began.
Measurement of radiocarbon was done by beta-counting devices, which counted the amount of beta radiation emitted by decaying 14C atoms in a sample. More accelerator mass spectrometry has become the method of choice; the development of radiocarbon dating has had a profound impact on archaeology. In addition to permitting more accurate dating within archaeological sites than previous methods, it allows comparison of dates of events across great distances. Histories of archaeology refer to its impact as the "radiocarbon revolution". Radiocarbon dating has allowed key transitions in prehistory to be dated, such as the end of the last ice age, the beginning of the Neolithic and Bronze Age in different regions. In 1939, Martin Kamen and Samuel Ruben of the Radiation Laboratory at Berkeley began experiments to determine if any of the elements common in organic matter had isotopes with half-lives long enough to be of value in biomedical research, they synthesized 14C using the laboratory's cyclotron accelerator and soon discovered that the atom's half-life was far longer than had been thought.
This was followed by a prediction by Serge A. Korff employed at the Franklin Institute in Philadelphia, that the interaction of thermal neutrons with 14N in the upper atmosphere would create 14C, it had been thought that 14C would be more to be created by deuterons interacting with 13C. At some time during World War II, Willard Libby, at Berkeley, learned of Korff's research and conceived the idea that it might be possible to use radiocarbon for dating. In 1945, Libby moved to the University of Chicago, he published a paper in 1946 in which he proposed that the carbon in living matter might include 14C as well as non-radioactive carbon. Libby and several collaborators proceeded to experiment with methane collected from sewage works in Baltimore, after isotopically enriching their samples they were able to demonstrate that they contained 14C. By contrast, methane created from petroleum showed no radiocarbon activity because of its age; the results were summarized in a paper in Science in 1947, in which the authors commented that their results implied it would be possible to date materials containing carbon of organic origin.
Libby and James Arnold proceeded to test the radiocarbon dating theory by analyzing samples with known ages. For example, two samples taken from the tombs of two Egyptian kings and Sneferu, independently dated to 2625 BC plus or minus 75 years, were dated by radiocarbon measurement to an average of 2800 BC plus or minus 250 years; these results were published in Science in 1949. Within 11 years of their announcement, more than 20 radiocarbon dating laboratories had been set up worldwide. In 1960, Libby was awarded the Nobel Prize in Chemistry for this work. In nature, carbon exists as two stable, nonradioactive isotopes: carbon-12, carbon-13, a radioactive isotope, carbon-14 known as "radiocarbon"; the half-life
Marmots are large squirrels in the genus Marmota, with 15 species. Some species live in mountainous areas, such as the Alps, northern Apennines, Carpathians and Pyrenees in Europe. Other species prefer rough grassland and can be found across North America and the Eurasian Steppe; the sized but more social prairie dog is not classified in the genus Marmota, but in the related genus Cynomys. Marmots live in burrows, hibernate there through the winter. Most marmots are social and use loud whistles to communicate with one another when alarmed. Marmots eat greens and many types of grasses, lichens, mosses and flowers; the following is a list of all Marmota species recognized by Thorington and Hoffman plus the defined M. kastschenkoi. They divide marmots into two subgenera. Genus Marmota – marmots Subgenus Marmota Alaska marmot, Brower's marmot, or Brooks Range marmot, M. broweri found in Alaska Alpine marmot, M. marmota found only in Europe in the Alps, northern Apennine Mountains in Italy, Carpathian Mountains, Tatra Mountains, reintroduced in the Pyrenees Black-capped marmot, M. camtschatica found in eastern Siberia Bobak marmot, M. bobak found from central Europe to central Asia Forest-steppe marmot, M. kastschenkoi found in south Russia Gray marmot or Altai marmot, M. baibacina found in Siberia Groundhog, woodchuck, or whistlepig, M. monax found in most of North America Himalayan marmot or Tibetan snow pig, M. himalayana found in the Himalayas Long-tailed marmot, golden marmot, or red marmot, M. caudata found in central Asia Menzbier's marmot, M. menzbieri found in central Asia Tarbagan marmot, Mongolian marmot, or tarvaga, M. sibirica found in Siberia Subgenus Petromarmota Hoary marmot, M. caligata found in northwestern North America Olympic marmot, M. olympus endemic to the Olympic Peninsula, United States Vancouver Island marmot, M. vancouverensis endemic to Vancouver Island, British Columbia, Canada Yellow-bellied marmot, M. flaviventris found in southwestern Canada and western United StatesAdditionally, four extinct species of marmots are recognized from the fossil record: †Marmota arizonae, Arizona, U.
S. †Marmota minor, Nevada, U. S. †Marmota robusta, China †Marmota vetus, Nebraska, U. S. Marmots have been known since antiquity. Research by the French ethnologist Michel Peissel claimed the story of the "Gold-digging ant" reported by the Ancient Greek historian Herodotus, who lived in the fifth century BCE, was founded on the golden Himalayan marmot of the Deosai Plateau and the habit of local tribes such as the Brokpa to collect the gold dust excavated from their burrows; the etymology of the term "marmot" is uncertain. It may have arisen from the Gallo-Romance prefix marm -, meaning to murmur. Another possible origin is post-classical Latin, mus montanus, meaning "mountain mouse". Beginning in 2010, Alaska celebrates February 2 as "Marmot Day", a holiday intended to observe the prevalence of marmots in that state and take the place of Groundhog Day; the Marmot Burrow International Marmot Network
Sandstone is a clastic sedimentary rock composed of sand-sized mineral particles or rock fragments. Most sandstone is composed of quartz or feldspar because they are the most resistant minerals to weathering processes at the Earth's surface, as seen in Bowen's reaction series. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, yellow, grey, pink and black. Since sandstone beds form visible cliffs and other topographic features, certain colors of sandstone have been identified with certain regions. Rock formations that are composed of sandstone allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Fine-grained aquifers, such as sandstones, are better able to filter out pollutants from the surface than are rocks with cracks and crevices, such as limestone or other rocks fractured by seismic activity. Quartz-bearing sandstone can be changed into quartzite through metamorphism related to tectonic compression within orogenic belts.
Sandstones are clastic in origin. They are formed from cemented grains that may either be fragments of a pre-existing rock or be mono-minerallic crystals; the cements binding these grains together are calcite and silica. Grain sizes in sands are defined within the range of 0.0625 mm to 2 mm. Clays and sediments with smaller grain sizes not visible with the naked eye, including siltstones and shales, are called argillaceous sediments; the formation of sandstone involves two principal stages. First, a layer or layers of sand accumulates as the result of sedimentation, either from water or from air. Sedimentation occurs by the sand settling out from suspension. Once it has accumulated, the sand becomes sandstone when it is compacted by the pressure of overlying deposits and cemented by the precipitation of minerals within the pore spaces between sand grains; the most common cementing materials are silica and calcium carbonate, which are derived either from dissolution or from alteration of the sand after it was buried.
Colors will be tan or yellow. A predominant additional colourant in the southwestern United States is iron oxide, which imparts reddish tints ranging from pink to dark red, with additional manganese imparting a purplish hue. Red sandstones are seen in the Southwest and West of Britain, as well as central Europe and Mongolia; the regularity of the latter favours use as a source for masonry, either as a primary building material or as a facing stone, over other forms of construction. The environment where it is deposited is crucial in determining the characteristics of the resulting sandstone, which, in finer detail, include its grain size and composition and, in more general detail, include the rock geometry and sedimentary structures. Principal environments of deposition may be split between terrestrial and marine, as illustrated by the following broad groupings: Terrestrial environmentsRivers Alluvial fans Glacial outwash Lakes Deserts Marine environmentsDeltas Beach and shoreface sands Tidal flats Offshore bars and sand waves Storm deposits Turbidites Framework grains are sand-sized detrital fragments that make up the bulk of a sandstone.
These grains can be classified into several different categories based on their mineral composition: Quartz framework grains are the dominant minerals in most clastic sedimentary rocks. These physical properties allow the quartz grains to survive multiple recycling events, while allowing the grains to display some degree of rounding. Quartz grains evolve from plutonic rock, which are felsic in origin and from older sandstones that have been recycled. Feldspathic framework grains are the second most abundant mineral in sandstones. Feldspar can be divided into two smaller subdivisions: plagioclase feldspars; the different types of feldspar can be distinguished under a petrographic microscope. Below is a description of the different types of feldspar. Alkali feldspar is a group of minerals in which the chemical composition of the mineral can range from KAlSi3O8 to NaAlSi3O8, this represents a complete solid solution. Plagioclase feldspar is a complex group of solid solution minerals that range in composition from NaAlSi3O8 to CaAl2Si2O8.
Lithic framework grains are pieces of ancient source rock that have yet to weather away to individual mineral grains, called lithic fragments or clasts. Lithic fragments can be any fine-grained or coarse-grained igneous, metamorphic, or sedimentary rock, although the most common lithic fragments found in sedimentary rocks are clasts of volcanic rocks. Accessory minerals are all other mineral grains in a sandstone. Common accessory minerals include micas, olivine and corundum. Many of these accessory grains are more dense than the silicates that
Antlers are extensions of an animal's skull found in members of the deer family. They are a single structure, they are found only on males, with the exception of the caribou. Antlers are shed and regrown each year and function as objects of sexual attraction and as weapons in fights between males for control of harems. In contrast, found on pronghorns and bovids such as sheep, goats and cattle, are two-part structures. An interior of bone is covered by an exterior sheath grown by specialized hair follicles, the same material as human fingernails and toenails. Horns continue to grow throughout the animal's life; the exception to this rule is the Pronghorn which regrows its horn sheath each year. They grow in symmetrical pairs. Antler comes from the Old French antoillier from some form of an unattested Latin word *anteocularis, "before the eye". Antlers are unique to cervids; the ancestors of deer had tusks. In most species, antlers appear to replace tusks. However, two modern species have tusks and no antlers and the muntjac has small antlers and tusks.
Antlers are found only on males. Only reindeer have antlers on the females, these are smaller than those of the males. Fertile does from other species of deer have the capacity to produce antlers on occasion due to increased testosterone levels; the "horns" of a pronghorn meet some of the criteria of antlers, but are not considered true antlers because they contain keratin. Each antler grows from an attachment point on the skull called a pedicle. While an antler is growing, it is covered with vascular skin called velvet, which supplies oxygen and nutrients to the growing bone. Antlers are considered one of the most exaggerated cases of male secondary sexual traits in the animal kingdom, grow faster than any other mammal bone. Growth occurs at the tip, is cartilage, replaced by bone tissue. Once the antler has achieved its full size, the velvet is lost and the antler's bone dies; this dead bone structure is the mature antler. In most cases, the bone at the base is destroyed by osteoclasts and the antlers fall off at some point.
As a result of their fast growth rate, antlers are considered a handicap since there is an immense nutritional demand on deer to re-grow antlers annually, thus can be honest signals of metabolic efficiency and food gathering capability. In most arctic and temperate-zone species, antler growth and shedding is annual, is controlled by the length of daylight. Although the antlers are regrown each year, their size varies with the age of the animal in many species, increasing annually over several years before reaching maximum size. In tropical species, antlers may be shed at any time of year, in some species such as the sambar, antlers are shed at different times in the year depending on multiple factors; some equatorial deer never shed their antlers. Antlers function as weapons in combats between males, which sometimes cause serious wounds, as dominance and sexual displays; the principal means of evolution of antlers is sexual selection, which operates via two mechanisms: male-to-male competition and female mate choice.
Male-male competition can take place in two forms. First, they can compete behaviorally where males use their antlers as weapons to compete for access to mates. Males with the largest antlers are more to obtain mates and achieve the highest fertilization success due to their competitiveness and high phenotypic quality. Whether this is a result of male-male fighting or display, or of female choosiness differs depending on the species as the shape and function of antlers vary between species. There is evidence to support that antler size influences mate selection in the red deer, has a heritable component. Despite this, a 30-year study showed no shift in the median size of antlers in a population of red deer; the lack of response could be explained by environmental covariance, meaning that lifetime breeding success is determined by an unmeasured trait, phenotypically correlated with antler size but for which there is no genetic correlation of antler growth. Alternatively, the lack of response could be explained by the relationship between heterozygosity and antler size, which states that males heterozygous at multiple loci, including MHC loci, have larger antlers.
The evolutionary response of traits that depend on heterozygosity is slower than traits that are dependent on additive genetic components and thus the evolutionary change is slower than expected. A third possibility is that the costs of having larger antlers exert enough selective pressure to offset the benefit of attracting mates. If antlers functioned only in male–male competition for mates, the best evolutionary strategy would be to shed them after the rutting season, both to free the male from a heavy encumbrance and to give him more time to regrow a larger new pair, yet antlers are retained through the winter and into the spring, suggesting that they have another use. Wolves in Yellowstone National Park are 3.6 times more to