Notably, there are about 82,000 feral horses that roam freely in the wild in certain parts of the country, mostly in the Western United States. While genus Equus, of which the horse is a member, originally evolved in North America, the horse became extinct on the continent approximately 8,000–12,000 years ago.
In 1493, on Christopher Columbus' second voyage to the Americas, Spanish horses, representing E. Catullus, were brought back to North America, first to the Virgin Islands ; they were reintroduced to the continental mainland by Hernán Cortés in 1519. From early Spanish imports to Mexico and Florida, horses moved north, supplemented by later imports to the east and west coasts brought by British, French, and other European colonists.
Native peoples of the Americas quickly obtained horses and developed their own horse culture that was largely distinct from European traditions. Horses remained an integral part of American rural and urban life until the 20th century, when the widespread emergence of mechanization caused their use for industrial, economic, and transportation purposes to decline.
Modern use of the horse in the United States is primarily for recreation and entertainment, though some horses are still used for specialized tasks. A 2005 genetic study of fossils found evidence for three genetically divergent equip lineages in Pleistocene North and South America.
Recent studies suggest all North American fossils of caballine-type horses, including both the domesticated horse and Przewalski's horse, belong to the same species: E. ferns. Remains attributed to a variety of species and lumped as New World stilt-legged horses belong to a second species that was endemic to North America, now called Haringtonhippus Francisco.
Digs in western Canada have unearthed clear evidence horses existed in North America as recently as 12,000 years ago. Other studies produced evidence that horses in the Americas existed until 8,000–10,000 years ago.
Equine in North America ultimately became extinct, along with most of the other New World megafauna during the Quaternary extinction event during the Pleistocene-Holocene transition between 15,000 and 10,000 years ago. Given the suddenness of the event and because these mammals had been flourishing for millions of years previously, something unusual must have happened.
The first main hypothesis attributes extinction to climate change. For example, in Alaska, beginning approximately 12,500 years ago, the grasses characteristic of a steppe ecosystem gave way to shrub tundra, which was covered with unpalatable plants.
However, it has also been proposed that the steppe-tundra vegetation transition in Bering may have been a consequence, rather than a cause, of the extinction of megafaunal grazers. The other hypothesis suggests extinction was linked to overexploitation of native prey by newly arrived humans.
The extinctions were roughly simultaneous with the end of the most recent glacial advance and the appearance of the big game-hunting Clovis culture. Several studies have indicated humans probably arrived in Alaska at the same time or shortly before the local extinction of horses.
Horses returned to the Americas thousands of years later, well after domestication of the horse, beginning with Christopher Columbus in 1493. These were Iberian horses first brought to Hispaniola and later to Panama, Mexico, Brazil, Peru, Argentina, and, in 1538, Florida.
The first horses to return to the main continent were 16 specifically identified horses brought by Hernán Cortés in 1519. Subsequent explorers, such as Coronado and De Soto brought ever-larger numbers, some from Spain and others from breeding establishments set up by the Spanish in the Caribbean.
The first imports were smaller animals suited to the size restrictions imposed by ships. Starting in the mid-19th century, larger draft horses began to be imported, and by the 1880s, thousands had arrived.
Formal horse racing in the United States dates back to 1665, when a racecourse was opened on the Hempstead Plains near Salisbury in what is now Nassau County, New York. There are multiple theories for how Native American people obtained horses from the Spanish, but early capture of stray horses during the 16th century was unlikely due to the need to simultaneously acquire the skills to ride and manage them.
It is unlikely that Native people obtained horses in significant numbers to become a horse culture any earlier than 1630–1650. From a trade center in the Santa Fe, New Mexico area, the horse spread slowly north.
The Comanche people were thought to be among the first tribes to obtain horses and use them successfully. By 1742, there were reports by white explorers that the Crow and Blackfoot people had horses, and probably had them for a considerable time.
The horse became an integral part of the lives and culture of Native Americans, especially the Plains Indians, who viewed them as a source of wealth and used them for hunting, travel, and warfare. In the 19th century, horses were used for many jobs.
In the west, they were ridden by cowboys for handling cattle on the large ranches of the region and on cattle drives. In some cases, their labor was deemed more efficient than using steam-powered equipment to power certain types of mechanized equipment.
At the same time, the maltreatment of horses in cities such as New York, where over 130,000 horses were used, led to the creation of the first ASPCA in 1866. In the 19th century, the Standard bred breed of harness racing horse developed in the United States, and many thoroughbred horse races were established.
Horse-drawn sightseeing bus, 1942At the start of the 20th century, the United States Department of Agriculture began to establish breeding farms for research, to preserve American horse breeds, and to develop horses for military and agricultural purposes. However, after the end of World War I, the increased use of mechanized transportation resulted in a decline in the horse populations, with a 1926 report noting horse prices were the lowest they had been in 60 years.
In 1912, the United States and Russia held the most horses in the world, with the U.S. having the second-highest number. There were an estimated 20 million horses in March 1915 in the United States.
But as increased mechanization reduced the need for horses as working animals, populations declined. A USDA census in 1959 showed the horse population had dropped to 4.5 million.
Numbers began to rebound somewhat, and by 1968 there were about 7 million horses, mostly used for riding. ^ One hypothesis posits that horses survived the ice age in North America, but no physical evidence has been found to substantiate this claim.
“Evolution, systematic, and paleogeography of Pleistocene horses in the New World: a molecular perspective”. “Ancient DNA Clarifies the Evolutionary History of American Late Pleistocene Equips”.
^ Hartman, Peter D; Paula, Grant D; Machete, Ross DE; Scott, Eric; Cahill, James A; Choose, Brianna K; Knapp, Joshua D; Stiller, Mathias; Woollier, Matthew J; Orlando, Ludovic; South on, John (November 28, 2017). “A new genus of horse from Pleistocene North America”.
“Rapid body size decline in Alaskan Pleistocene horses before extinction”. “Steppe-tundra transition: a herbivore-driven biome shift at the end of the Pleistocene”.
“A calendar chronology for Pleistocene mammoth and horse extinction in North America based on Bayesian radiocarbon calibration”. ^ Slow, Andrew; Roberts, David; Robert, Karen (May 9, 2006).
“On the Pleistocene extinctions of Alaskan mammoths and horses ". Proceedings of the National Academy of Sciences of the United States of America (19 ed.).
“New carbon dates link climatic change with human colonization and Pleistocene extinctions”. “Iberian Origins of New World Horse Breeds”.
Report of the Chief of the Bureau of Animal Industry, United States Department of Agriculture. Horses in Society: A Story of Animal Breeding and Marketing, 1800–1920.
Image credit: Panel Uchorczak/Shutterstock It is commonly believed that horses are native to the European lands, when in reality, their ancestors came over from the Americas via the Bering Bridge 1 million years ago. Horses agility and intelligence contributes to their pest-like behavior of consuming crops in large amounts, which is unfavorable to farmers.
As the only method for transportation, their purpose was also to help with carrying loads for settlements and to trade with the Indigenous peoples. The name Phipps was given to the earliest species by Thomas Henry Huxley, an English biologist and anthropologist who specialized in comparative anatomy, upon his visit to the United States in 1876.
Literally meaning “dawn horse,” Phipps was described as a “timid forest animal” standing at about 13 inches tall, with a hunched back, leopard-like spots, and four toes on each foot. Having acquired an additional tooth for grinding to feed on tough plants, it also presented itself with a sturdier body.
It not only looked like today's, with its elongated snout and long legs (albeit still with three toes), but it also demonstrated agility and intelligence through its ability to escape and out-trick other species as well as humans who made attempts a domesticating the Merrychipus. Equus managed to make its way through Alaska into Siberia via the Bering Bridge, about 1,000,000 years ago, spreading by land through Asia and Europe all the way to Africa.
Although it remains uncertain why they went extinct on these lands, evidence suggests that humans might have had something to do with it, as they first made their way to the Americas from Siberia by crossing the Bering Strait around that time. The other two theories state that infectious disease and climate change with a consecutive decline in vegetation might have also been the contributing factors.
A little-known fact is that horses, wild horses specifically, can be regarded as pests, as they are capable of consuming large amounts of land resources at a time, including feed for farmers' cattle and the products that farmers grow themselves, such as cabbage, carrots and leafy greens. The last prehistoric North American horses died out between 13,000 and 11,000 years ago, at the end of the Pleistocene, but by then Equus had spread to Asia, Europe, and Africa.
In any case the domesticated horse probably did not arise at a single place and time, but was bred from several wild varieties by Eurasian herders. In recent years, molecular biology has provided new tools for working out the relationships among species and subspecies of equips.
For example, based on mutation rates for mitochondrial DNA (mt DNA) Ann Forster, of the Zoological Institute at the University of Helsinki, has estimated that E. Catullus originated approximately 1.7 million years ago in North America. Her examination of E. samba mt DNA (preserved in the Alaskan permafrost) has revealed that the species is genetically equivalent to E. Catullus.
That conclusion has been further supported by Michael Forfeited, of the Department of Evolutionary Genetics at the Max Planck Institute in Leipzig, Germany, who has found that the variation fell within that of modern horses. Indeed, domestication altered them little, as we can see by how quickly horses revert to ancient behavioral patterns in the wild.
The wild horse in the United States is generally labeled non-native by most federal and state agencies dealing with wildlife management, whose legal mandate is usually to protect native wildlife and prevent non-native species from having ecologically harmful effects. Jay F. Kirkpatrick, who earned a Ph.D. in reproductive physiology from the College of Veterinary Medicine at Cornell University, has studied fertility control for wild horses.
Patricia M. Fabio, a research fellow at the Science and Conservation Center, earned her Ph.D. in environmental history from Texas A&M University. Her interests include reproductive physiology, the monitoring of wild horse ranges, and the evolution of equips.
Its popular knowledge that European colonists brought horses over to America during the 15th and 16th century to be traded with the Native Americans, hence the Thanksgiving association. Around 10,000 years ago, some of these wild horses crossed over the Bering land bridge that connected early America and Asia.
The ancient wild horses that stayed in America became extinct, possibly due to climate changes, but their ancestors were introduced back to the American land via the European colonists many years later. This is where problems emerge, because although they were once native to America thousands of years ago, horses are still technically a recently introduced species to the American plains.
However, their populations grew too quickly, and they began to compete with farmers for the natural resources that the land held. The horses we see today are all examples of selective breeding via humans over the years, but they’re also a shared part of our mixed Native and European histories.
Horses allowed humans to travel farther and faster, instrumentally help out armies during battles, and develop the country through labor-intensive agriculture. Today, veterinary technicians such as the graduates of Before work with horses and many other animals to provide the care they need to thrive.
Small and Large Animal Training Facilities including on-site surgery, radiology and dental suites. This accreditation is a requirement in order to take the Veterinary Technician National Exam for credentialing upon graduation.
Course Curriculum specifically designed to provide the students the skills and opportunities they will need to be successful in the Veterinary field. TRUE OR FALSE: The Spanish explorers’ horses were the first of their species to set foot on the North American continent.
As a result, the conquistadors were able to vanquish large numbers of Indians with a relative handful of men. Of course, the Indians eventually overcame their fear and acquired horses of their own, gathering strays or stealing from the settlers’ bands and becoming expert horsemen.
Sheep wars occurred in many western states though they were most common in Texas, Arizona and the border region of Wyoming and Colorado. Generally, the cattlemen saw the sheepherders as invaders, who destroyed the public grazing lands, which they had to share on a first-come, first-served basis.
Over the last century, this has led to the deionization of grazing animals who compete with cattle for forage on public lands. These days most grazing herbivores, wild or domestic, have lobbies based on an economic interest.
The economic value of cattle, sheep and pigs are obvious, due to the market demands for these animals as human food sources. Below we examine the three greatest myths that the cattle industry has perpetrated regarding America’s wild horses.
These myths were relatively easily perpetrated during the time that predated the Internet, when advanced scientific information was available via relatively few and obscure resources. In fact, all horses on the planet today originated from North America and migrated over the Aleutian land bridge into Asia sometime around 17,000 years ago.
Dr. Ross Machete, curator of vertebrates at the American Museum of Natural History, has criticized the BLM (Bureau of Land Management) for publishing manifestly incorrect information for public viewing on their wild burro and horse website. Furthermore, according to Professors Kirkpatrick and Fabio, in their article Wild Horses as Native North American Wildlife : “The issue of realization and the use of the word ‘feral’ is a human construct that has little biological meaning except in transitory behavior, usually forced on the animal in some manner.
E. Przewalskii (Mongolian wild horses) disappeared from Mongolia a hundred years ago. They had in fact made contact with the Lakota Indians, who resided on the plains that stretched between the Mississippi River and the Rocky Mountains, and observed them riding horses and hunting buffalo using methods and tools (evolved spear designs) that were advanced at that place and time.
The journals of these explorer-cartographers are now being studied from their secure locations in museums, where scientists have uncovered illuminating revelations of wild horses being tamed and ridden for centuries in America before the arrival of French explorers in the early 1600s, thus predating the arrival of any Spaniards and even the Vikings on the North American continent. In the field of Molecular Biology there are new studies that point to the conclusion that the wild horses in America today are a native species.
This article discusses that subject in depth, and in short states: “The work of Michael Forfeited examining the genetics of the called E. samba from the permafrost of Alaska, found that the variation was within that of modern horses, which translates into E. samba actually being E. Catullus, genetically.” Thus, as Forfeited adds, “the molecular biology evidence is incontrovertible and indisputable, and is also supported by the interpretation of the fossil record, as well.” A study by Hansen, Clark and Law horn titled Foods of Wild Horses, Deer and Cattle in the Douglas Mountain Areas, Colorado shows that wild horses do not adversely compete with deer for food.
Black tail deer in western coastal areas similarly have little potential for grazing competition with wild horses. Wildlife biologists characterize the grazing adaptation shared between wild horses and corvids (the deer family) as being ‘communal,’ meaning they essentially eat from the same table without competing.
Arguably one of the cattle industry’s favorite whoppers is that wild horses damage range and riparian lands. Cattle require intensive management to minimize the extensive damage they do to pastures, especially wetlands and riparian areas.
It is also important to note that cattle have an evolutionary adaptive hoof design that arguably provides extra traction in wetlands, which are their preferred homesteads in a native ecosystem. Another ecological downside to cattle is their multi-stomach ruminant digestive system, which is quite effective at digesting most of the plant and grass seeds they consume when grazing native pastures, rending those seeds non-viable and thereby eliminating the natural reseeding process of the plants and grasses consumed.
Wild horses have many other mutual isms within the ecosystems of the American landscapes they inhabit, including with trees, which they adopt as their means of shelter from the heat of summer and rains and snows of winter. In return, wild horses graze down all the grasses and plants under the trees, thus removing fuel for wildfires.
As we consider the foregoing points, it becomes strikingly obvious that millennia of evolutionary processes have led to complex mutual isms between plants, grasses and wild horses. The cattle industry attempts to paint wild horses as a current problem on public lands by stating they are damaging to rang elands.
So as we can now see, the cattle industry and others who repeat these myths and false narratives have done and continue to do a grave injustice to the reputation and the natural history of America’s wild horses, which have been a great blessing to mankind, literally a gift from the Creator. Reconstruction, left forefoot skeleton (third digit emphasized yellow) and longitudinal section of molars of selected prehistoric horses The evolution of the horse, a mammal of the family Equine, occurred over a geologic timescale of 50 million years, transforming the small, dog-sized, forest-dwelling Phipps into the modern horse.
Paleo zoologists have been able to piece together a more complete outline of the evolutionary lineage of the modern horse than of any other animal. Much of this evolution took place in North America, where horses originated but became extinct about 10,000 years ago.
The horse belongs to the order Perissodactyla (odd-toed ungulates), the members of which all share hooked feet and an odd number of toes on each foot, as well as mobile upper lips and a similar tooth structure. This means that horses share a common ancestry with tapirs and rhinoceroses.
The perissodactyls arose in the late Paleocene, less than 10 million years after the Cretaceous–Paleogene extinction event. This group of animals appears to have been originally specialized for life in tropical forests, but whereas tapirs and, to some extent, rhinoceroses, retained their jungle specializations, modern horses are adapted to life on drier land, in the much harsher climatic conditions of the steppes.
Other species of Equus are adapted to a variety of intermediate conditions. The early ancestors of the modern horse walked on several spread-out toes, accommodation to life spent walking on the soft, moist grounds of primeval forests.
As grass species began to appear and flourish, the equips diets shifted from foliage to grasses, leading to larger and more durable teeth. At the same time, as the steppes began to appear, the horse's predecessors needed to be capable of greater speeds to outrun predators.
In the 1760s, the early naturalist Buffoon suggested this was an indication of inferiority of the New World fauna, but later reconsidered this idea. William Clark's 1807 expedition to Big Bone Lick found “leg and foot bones of the Horses “, which were included with other fossils sent to Thomas Jefferson and evaluated by the anatomist Caspar Wis tar, but neither commented on the significance of this find.
The first Old World equip fossil was found in the gypsum quarries in Montmartre, Paris, in the 1820s. His sketch of the entire animal matched later skeletons found at the site.
During the Beagle survey expedition, the young naturalist Charles Darwin had remarkable success with fossil hunting in Patagonia. On 10 October 1833, at Santa Fe, Argentina, he was “filled with astonishment” when he found a horse's tooth in the same stratum as fossil giant armadillos, and wondered if it might have been washed down from a later layer, but concluded this was “not very probable”.
After the expedition returned in 1836, the anatomist Richard Owen confirmed the tooth was from an extinct species, which he subsequently named Equus curves, and remarked, “This evidence of the former existence of a genus, which, as regards South America, had become extinct, and has a second time been introduced into that Continent, is not one of the least interesting fruits of Mr. Darwin's palæontological discoveries.” In 1848, a study On the fossil horses of America by Joseph Lady systematically examined Pleistocene horse fossils from various collections, including that of the Academy of Natural Sciences, and concluded at least two ancient horse species had existed in North America: Equus curves and another, which he named Equus Americans.
The original sequence of species believed to have evolved into the horse was based on fossils discovered in North America in 1879 by paleontologist Thiel Charles Marsh. The sequence, from Phipps to the modern horse (Equus), was popularized by Thomas Huxley and became one of the most widely known examples of a clear evolutionary progression.
The horse's evolutionary lineage became a common feature of biology textbooks, and the sequence of transitional fossils was assembled by the American Museum of Natural History into an exhibit that emphasized the gradual, “straight-line” evolution of the horse. Since then, as the number of equip fossils has increased, the actual evolutionary progression from Phipps to Equus has been discovered to be much more complex and multibranched than was initially supposed.
George Gaylord Simpson in 1951 first recognized that the modern horse was not the “goal” of the entire lineage of equips, but is simply the only genus of the many horse lineages to survive. Although some transitions, such as that of Dinohippus to Equus, were indeed gradual progressions, a number of others, such as that of Phipps to Mesohippus, were relatively abrupt in geologic time, taking place over only a few million years.
Both an agenesis (gradual change in an entire population's gene frequency) and cladogenesis (a population “splitting” into two distinct evolutionary branches) occurred, and many species coexisted with “ancestor” species at various times. The change in equips' traits was also not always a “straight line” from Phipps to Equus : some traits reversed themselves at various points in the evolution of new equip species, such as size and the presence of facial fossa, and only in retrospect can certain evolutionary trends be recognized.
Phipps appeared in the Persian (early Eocene), about 52 MYA (million years ago). It was an animal approximately the size of a fox (250–450 mm in height), with a relatively short head and neck and a springy, arched back.
It had 44 low-crowned teeth, in the typical arrangement of an omnivorous, browsing mammal: three incisors, one canine, four premolars, and three molars on each side of the jaw. Its molars were uneven, dull, and bumpy, and used primarily for grinding foliage.
The cusps of the molars were slightly connected in low crests. Phipps browsed on soft foliage and fruit, probably scampering between thickets in the mode of a modern mental.
Its limbs were long relative to its body, already showing the beginnings of adaptations for running. The forelimbs had developed five toes, of which four were equipped with small proto-hooves; the large fifth “toe-thumb” was off the ground.
Its feet were padded, much like a dog's, but with the small hooves in place of claws. For a span of about 20 million years, Phipps thrived with few significant evolutionary changes.
The most significant change was in the teeth, which began to adapt to its changing diet, as these early Equine shifted from a mixed diet of fruits and foliage to one focused increasingly on browsing foods. Thousands of complete, fossilized skeletons of these animals have been found in the Eocene layers of North American strata, mainly in the Wind River basin in Wyoming.
Similar fossils have also been discovered in Europe, such as Propalaeotherium (which is not considered ancestral to the modern horse). Approximately 50 million years ago, in the early-to-middle Eocene, Phipps smoothly transitioned into Orohippus through a gradual series of changes.
It resembled Phipps in size, but had a slimmer body, an elongated head, slimmer forelimbs, and longer hind legs, all of which are characteristics of a good jumper. In the mid-Eocene, about 47 million years ago, Phipps, a genus which continued the evolutionary trend of increasingly efficient grinding teeth, evolved from Orohippus.
A late species of Phipps, sometimes referred to as Duchesnehippus intermedia, had teeth similar to Oligocene equips, although slightly less developed. Whether Duchesnehippus was a subgenus of Phipps or a distinct genus is disputed.
In the late Eocene and the early stages of the Oligocene epoch (32–24 MYA), the climate of North America became drier, and the earliest grasses began to evolve. The forests were yielding to flatland, home to grasses and various kinds of brush.
In a few areas, these plains were covered in sand, creating the type of environment resembling the present-day prairies. In the late Eocene, they began developing tougher teeth and becoming slightly larger and leggier, allowing for faster running speeds in open areas, and thus for evading predators in nonwooded areas .
In the early Oligocene, Mesohippus was one of the more widespread mammals in North America. Judging by its longer and slimmer limbs, Mesohippus was an agile animal.
Mesohippus was slightly larger than Phipps, about 610 mm (24 in) at the shoulder. Its back was less arched, and its face, snout, and neck were somewhat longer.
It had significantly larger cerebral hemispheres, and had a small, shallow depression on its skull called a fossa, which in modern horses is quite detailed. The fossa serves as a useful marker for identifying an equine fossil's species.
As with Mesohippus, the appearance of Miohippus was relatively abrupt, though a few transitional fossils linking the two genera have been found. Miohippus was significantly larger than its predecessors, and its ankle joints had subtly changed.
Its facial fossa was larger and deeper, and it also began to show a variable extra crest in its upper cheek teeth, a trait that became a characteristic feature of equine teeth. Miohippus ushered in a major new period of diversification in Equine.
The forest-suited form was Kalobatippus (or Miohippus intermedia, depending on whether it was a new genus or species), whose second and fourth front toes were long, well-suited to travel on the soft forest floors. Kalobatippus probably gave rise to Anchitherium, which travelled to Asia via the Bering Strait land bridge, and from there to Europe.
The Miohippus population that remained on the steppes is believed to be ancestral to Parahippus, a North American animal about the size of a small pony, with a prolonged skull and a facial structure resembling the horses of today. Its third toe was stronger and larger, and carried the main weight of the body.
Its four premolars resembled the molar teeth; the first were small and almost nonexistent. In the middle of the Miocene epoch, the grazer Merychippus flourished.
It had wider molars than its predecessors, which are believed to have been used for crunching the hard grasses of the steppes. The hind legs, which were relatively short, had side toes equipped with small hooves, but they probably only touched the ground when running.
Three lineages within Equine are believed to be descended from the numerous varieties of Merychippus : Riparian, Protohippus and Pliohippus. The most different from Merychippus was Riparian, mainly in the structure of tooth enamel : in comparison with other Equine, the inside, or tongue side, had a completely isolated parapet.
A complete and well-preserved skeleton of the North American Riparian shows an animal the size of a small pony. They were very slim, rather like antelopes, and were adapted to life on dry prairies.
In North America, Riparian and its relatives (Cormohipparion, Nannies, Neohipparion, and Pseudhipparion), proliferated into many kinds of equips, at least one of which managed to migrate to Asia and Europe during the Miocene epoch. Pliohippus arose from Calliopes in the middle Miocene, around 12 MYA.
It was very similar in appearance to Equus, though it had two long extra toes on both sides of the hoof, externally barely visible as callused stubs. The long and slim limbs of Pliohippus reveal a quick-footed steppe animal.
Until recently, Pliohippus was believed to be the ancestor of present-day horses because of its many anatomical similarities. Dinohippus was the most common species of Equine in North America during the late Pliocene.
It was originally thought to be monodactyl, but a 1981 fossil find in Nebraska shows some were pterodactyl. Plesippus is often considered an intermediate stage between Dinohippus and the extant genus, Equus.
The famous fossils found near German, Idaho were originally thought to be a part of the genus Plesippus. German Fossil Beds (Idaho) is a Pliocene site, dating to about 3.5 MYA.
The fossilized remains were originally called Plesippus Shoshones, but further study by paleontologists determined the fossils represented the oldest remains of the genus Equus. Their estimated average weight was 425 kg, roughly the size of an Arabian horse.
At the end of the Pliocene, the climate in North America began to cool significantly and most of the animals were forced to move south. One population of Plesippus moved across the Bering land bridge into Eurasia around 2.5 MYA.
Skull of a giant extinct horse, Equus eisenmannae The genus Equus, which includes all extant equines, is believed to have evolved from Dinohippus, via the intermediate form Plesippus. The oldest fossil to date is ~3.5 million years old from Idaho, USA.
The genus appears to have spread quickly into the Old World, with the similarly aged Equus livenzovensis documented from Western Europe and Russia. Molecular phylogeny indicate the most recent common ancestor of all modern equips (members of the genus Equus) lived ~5.6 (3.9–7.8) MYA.
Direct paleogenomic sequencing of a 700,000-year-old middle Pleistocene horse metaphorical bone from Canada implies a more recent 4.07 MYR before present date for the most recent common ancestor (MRCA) within the range of 4.0 to 4.5 MYR BP. The oldest divergences are the Asian heroines (subgenus E. (Sinus) , including the Klan, Onsager, and King), followed by the African zebras (subgenera E. (Dolichohippus) , and E. (Hippotigris) ).
All other modern forms including the domesticated horse (and many fossil Pliocene and Pleistocene forms) belong to the subgenus E. (Equus) which diverged ~4.8 (3.2–6.5) million years ago. Pleistocene horse fossils have been assigned to a multitude of species, with over 50 species of equines described from the Pleistocene of North America alone, although the taxonomic validity of most of these has been called into question.
Remains attributed to a variety of species and lumped as New World stilt-legged horses (including H. Francisco, E. tau, E. Quinn and potentially North American Pleistocene fossils previously attributed to E. cf. Kiang) probably all belong to a second species endemic to North America, which despite a superficial resemblance to species in the subgenus E. (Sinus) (and hence occasionally referred to as North American ass) is closely related to E. ferns.
Surprisingly, the third species, endemic to South America and traditionally referred to as Hippidion, originally believed to be descended from Pliohippus, was shown to be a third species in the genus Equus, closely related to the New World stilt-legged horse. The temporal and regional variation in body size and morphological features within each lineage indicates extraordinary interspecific plasticity.
Such environment-driven adaptation changes would explain why the taxonomic diversity of Pleistocene equips has been overestimated on morphoanatomical grounds. According to these results, it appears the genus Equus evolved from a Dinohippus -like ancestor ~4–7 MYA.
It rapidly spread into the Old World and there diversified into the various species of asses and zebras. A North American lineage of the subgenus E. (Equus) evolved into the New World stilt-legged horse (Nash).
Subsequently, populations of this species entered South America as part of the Great American Interchange shortly after the formation of the Isthmus of Panama, and evolved into the form currently referred to as Hippidion ~2.5 million years ago. Hippidion is thus only distantly related to the morphologically similar Pliohippus, which presumably became extinct during the Miocene.
Both the Nash and Iridium show adaptations to dry, barren ground, whereas the shortened legs of Hippidion may have been a response to sloped terrain. In contrast, the geographic origin of the closely related modern E. ferns is not resolved.
However, genetic results on extant and fossil material of Pleistocene age indicate two clades, potentially subspecies, one of which had a Arctic distribution spanning from Europe through Asia and across North America and would become the founding stock of the modern domesticated horse. However, one or more North American populations of E. ferns entered South America ~1.0–1.5 million years ago, leading to the forms currently known as E. (Amerhippus), which represent an extinct geographic variant or race of E. ferns.
The evolutionary divergence of the two populations was estimated to have occurred about 45,000 GBP, while the archaeological record places the first horse domestication about 5,500 GBP by the ancient central-Asian Bowie culture. The two lineages thus split well before domestication, probably due to climate, topography, or other environmental changes.
Several subsequent DNA studies produced partially contradictory results. A 2009 molecular analysis using ancient DNA recovered from archaeological sites placed Przewalski's horse in the middle of the domesticated horses, but a 2011 mitochondrial DNA analysis suggested that Przewalski's and modern domestic horses diverged some 160,000 years ago.
An analysis based on whole genome sequencing and calibration with DNA from old horse bones gave a divergence date of 38–72 thousand years ago. In June 2013, a group of researchers announced that they had sequenced the DNA of a 560–780 thousand-year-old horse, using material extracted from a leg bone found buried in permafrost in Canada's Yukon territory.
Before this publication, the oldest nuclear genome that had been successfully sequenced was dated at 110–130 thousand years ago. Analysis of differences between these genomes indicated that the last common ancestor of modern horses, donkeys, and zebras existed 4 to 4.5 million years ago.
A new analysis in 2018 involved genomic sequencing of ancient DNA from mid-fourth-millennium B.C.E. The study revealed that Przewalski's horses not only belong to the same genetic lineage as those from the Bowie culture, but were the feral descendants of these ancient domestic animals, rather than representing a surviving population of never-domesticated horses.
In comparison, the chromosomal differences between domestic horses and zebras include numerous translocation, fusions, inversions and centromere repositioning. This gives Przewalski's horse the highest diploid chromosome number among all equine species.
They can interbreed with the domestic horse and produce fertile offspring (65 chromosomes). Digs in western Canada have unearthed clear evidence horses existed in North America until about 12,000 years ago.
Given the suddenness of the event and because these mammals had been flourishing for millions of years previously, something quite unusual must have happened. The first main hypothesis attributes extinction to climate change.
For example, in Alaska, beginning approximately 12,500 years ago, the grasses characteristic of a steppe ecosystem gave way to shrub tundra, which was covered with unpalatable plants. The other hypothesis suggests extinction was linked to overexploitation by newly arrived humans of naive prey that were not habituated to their hunting methods.
The extinctions were roughly simultaneous with the end of the most recent glacial advance and the appearance of the big game-hunting Clovis culture. Several studies have indicated humans probably arrived in Alaska at the same time or shortly before the local extinction of horses.
Additionally, it has been proposed that the steppe-tundra vegetation transition in Bering may have been a consequence, rather than a cause, of the extinction of megafaunal grazers. In Eurasia, horse fossils began occurring frequently again in archaeological sites in Kazakhstan and the southern Ukraine about 6,000 years ago.
From then on, domesticated horses, as well as the knowledge of capturing, taming, and rearing horses, probably spread relatively quickly, with wild mares from several wild populations being incorporated en route. These were Iberian horses first brought to Hispaniola and later to Panama, Mexico, Brazil, Peru, Argentina, and, in 1538, Florida.
Subsequent explorers, such as Coronado and De Soto, brought ever-larger numbers, some from Spain and others from breeding establishments set up by the Spanish in the Caribbean. Modern horses retain the splint bones; they are often believed to be useless attachments, but they in fact play an important role in supporting the carpal joints (front knees) and even the tarsal joints (hocks).
Throughout the phylogenetic development, the teeth of the horse underwent significant changes. The type of the original omnivorous teeth with short, “bumpy” molars, with which the prime members of the evolutionary line distinguished themselves, gradually changed into the teeth common to herbivorous mammals.
They became long (as much as 100 mm), roughly cubical molars equipped with flat grinding surfaces. In conjunction with the teeth, during the horse's evolution, the elongation of the facial part of the skull is apparent, and can also be observed in the backward-set eye holes.
In addition, the relatively short neck of the equine ancestors became longer, with equal elongation of the legs. Reconstruction of possible ancestral coat colors. The ancestral coat color of E. ferns was possibly a uniform dun, consistent with modern populations of Przewalski's horses.
Pre-domestication variants including black and spotted have been inferred from cave wall paintings and confirmed by genomic analysis. Les comminutes DE mammies Du Paleogene (Eocene superior ET Oligocene) d'Europe Occidental : structures, milieux ET evolution.
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ISBN 0-19-500104-4 (1971 reprint) ^ The notion of a goal would contradict modern evolutionary synthesis, ^ a b c Hunt, Kathleen (1995). “Sadistic analysis of primitive equips with notes on other perissodactyls”.
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^ a b c Mach ugh, David E.; Larson, Greer; Orlando, Ludovic (2016). “Taming the past: Ancient DNA and the study of animal domestication”.
“Evolutionary genomics and conservation of the endangered Przewalski's horse”. CS1 main: multiple names: authors list (link) ^ Outran, A.K.
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^ Forfeited, Michael; Ludwig, Are; Provost, Melanie; Batsman, Monika; Bedecked, Norbert; Brockman, Guru A; Castaño, Pedro; Paisley, Michael; Leopold, Sebastian; Florence, Laura; Malaysians, Anna-Sapfo; Slat kin, Montgomery (2009). “Coat Color Variation at the Beginning of Horse Domestication”.
Today's horses represent just one tiny twig on an immense family tree that spans millions of years. Some 10 million years ago, up to a dozen species of horses roamed the Great Plains of North America.
A small, three-toed Nannies, shown here eating shrubs, ate both grass and leaves. In the background are several other large mammals alive at that time, including Procamelus, a camel relative; a herd of Dinohippus horses ; Gomphotherium, a distant relative of true elephants; and Telenovelas, a hornless rhinoceros.
By 55 million years ago, the first members of the horse family, the dog-sized Hyracotherium, were scampering through the forests that covered North America. But changing climate conditions allowed grasslands to expand, and about 20 million years ago, many new species rapidly evolved.
Some--but not all--became larger and had the familiar hooves and grazing diets that we associate with horses today. Little Nannies, shown in the diorama at full adult size, was actually smaller than its predecessors.
The Dinohippus shown grazing on the left is a close relative of horses today. In North America, the wild horse is often labeled as a non-native, or even an exotic species, by most federal or state agencies dealing with wildlife management, such as the National Park Service, US Fish and Wildlife Service, and the Bureau of Land Management.
The legal mandate for many of these agencies is to protect native wildlife and prevent non-native species from causing harmful effects on the general ecology of the land. If the idea that wild horses were, indeed, native wildlife, a great many current management approaches might be compromised.
The precise date of origin for the genus Equus is unknown, but evidence documents the dispersal of Equus from North America to Eurasia approximately 2–3 million years ago and a possible origin at about 3.4–3.9 million years ago. Dr. Ross Machete, Curator of Mamma logy at the American Museum of Natural History, and colleagues, have dated the existence of woolly mammoths and horses in North America to as recent as 7,600 years ago.
Had it not been for previous westward migration, over the 2 Bering Land Bridge, into northwestern Russia (Siberia) and Asia, the horse would have faced complete extinction. In 1493, on Columbus’ second voyage to the Americas, Spanish horses, representing E. Catullus, were brought back to North America, first in the Virgin Islands, and, in 1519, they were reintroduced on the continent, in modern-day Mexico, from where they radiated throughout the American Great Plains, after escape from their owners or by pilfering (Fabio 1995).
Equus, a monophyletic taxon, is first represented in the North American fossil record about four million years ago by E. simplifies, and this species is directly ancestral to later Blanca species about three million years ago (Harold and Voorhees 1990). Azzaroli (1992) believed, again on the basis of fossil records, that E. simplifies gave rise to the late Pliocene E. Idahoans, and that species, in turn, gave rise to the first tabloid horses two million years ago in North America.
By ecomorphotype, we refer to differing phenotypic or physical characteristics within the same species, caused by genetic isolation in discrete habitats. In North America, isolated lower molar teeth and a mandible from sites of the Irvington age appear to be E. Catullus, morphologically.
While earlier taxonomists tried to deal with the subjectivity of choosing characters they felt would adequately describe, and thus group, genera and species, these observations were lacking in precision. Nevertheless, the more subjective pale ontological data strongly suggests the origin of E. Catullus somewhere between one and two million years ago.
A series of genetic analyses, carried out at the San Diego Zoo’s Center for Reproduction in Endangered Species, and based on chromosome differences (Benirschke et al. 1965) and mitochondrial genes (George and Ryder 1986) both indicate significant genetic divergence among several forms of wild E. Catullus as early as 200,000–300,000 years ago. 4 The relatively new (30-year-old) field of molecular biology, using mitochondrial-DNA analysis, has recently revealed that the modern or cabal line horse, E. Catullus, is genetically equivalent to E. samba, a horse, according to fossil records, that represented the most recent Equus species in North America prior to extinction.
According to the work of researchers from Appeal University of the Department of Evolutionary Biology (Forster 1992), the date of origin, based on mutation rates for mitochondrial-DNA, for E. Catullus, is set at approximately 1.7 million years ago in North America. Charles Vila, also of the Department of Evolutionary Biology at Appeal University, has corroborated Forster’s work.
Vila et al. (2001) have shown that the origin of domestic horse lineages was extremely widespread, over time and geography, and supports the existence of the tabloid horse in North American before its disappearance, corroborating the work of Benirschke et al. (1965), George and Ryder (1995), and Hubbard (1955). A study conducted at the Ancient Biomolecules Center of Oxford University (Winston et al. 2005) also corroborates the conclusions of Forster (1992).
Despite a great deal of variability in the size of the Pleistocene equips from differing locations (mostly ecomorphotypes), the DNA evidence strongly suggests that all the large and small cabal line samples belonged to the same species. In another study, Kruger et al. (2005), using micro satellite data, confirms the work of Forster (1992) but gives a wider range for the emergence of the tabloid horse, of 0.86 to 2.3 million years ago.
Fast and McCullough (1976) dubbed this “social conservation” in his paper on behavior patterns and communication in the Pryor Mountain wild horses. The non-native, feral, and exotic designations given by agencies are not merely reflections of their failure to understand modern science but also a reflection of their desire to preserve old ways of thinking to keep alive the conflict between a species (wild horses), with no economic value any more (by law), and the economic value of commercial livestock.
Native status for wild horses would place these animals, under law, within a new category for management considerations. As a form of wildlife, embedded with wildness, ancient behavioral patterns, and the morphology and biology of a sensitive prey species, they may finally be released from the “livestock-gone-loose” appellation.
Jay F. Kirkpatrick, Director, The Science and Conservation Center, Zoo Montana, Billings, holds a Ph.D. in reproductive physiology from the College of Veterinary Medicine at Cornell University. Patricia M. Fabio, Research Fellow, The Science and Conservation Center, Zoo Montana, Billings, holds a B.S.
However, this article may be copied and distributed freely in hard copy, electronic, or website form, for educational purposes only. The map at left is from Story's Illustrated Guide to 96 Horse Breeds of North America by Judith Dotson.
Pope Alexander VI in 1493 granted Spain dominion over all lands, discovered or undiscovered, in the New World. Expeditions that sought out new lands and treasures brought horses with them from the islands.
The earliest exploratory expeditions went to Mexico in 1517 (Cordoba) and 1518 (Bridalveil), but did not bring horses. By June of that year, he established the settlement of Villa Rica de la Vera Cruz.
During this time, Cortés received reinforcements and supplies, including more horses from Cuba. Over the next few decades, more Spanish settlers came to the Mexican mainland bringing with them livestock from the Islands.
From 1535-1542, explorers with Francisco de Coronado reached as far north as areas that are now in Arizona and New Mexico, including the Grand Canyon, and into Texas, Oklahoma and Kansas. This area of Mexico is relatively isolated on the coast because of the high mountains with dense cloud forests, so the horses remained relatively pure.
Preliminary results of genetic tests done by Dr. E. Gus Cochran at Texas A&M University on our Aliens show them to be closest to the Warrant horses (also called Min ho) of Portugal, a primitive horse of the Iberian Peninsula. This gave plenty of opportunity for native peoples to take horses and other livestock, and for feral herds to develop.
Over the centuries, these Colonial Spanish horse populations have bred within their own herds and have remained relatively genetically pure. Hardy Else in the book “Born Survivors on the Eve of Extinction” writing about Spanish Mustangs suggests that it is because the Spanish Colonial horses are clannish, avoiding horses of other breeds.
Many of the Horse Breed accounts overly simplify history and include unsubstantiated conjecture, resulting in some erroneous beliefs and conclusions. What we now consider Aliens are the result of nearly 500 years of natural selection within the feral herds in southern Mexico.
Records also show that these horses were brought along with missionaries as they established outposts throughout Mexico and what is now southwestern USA. Settlements in South America apparently tended to keep their horses under closer control with very selective breeding programs.
Similarly, Danilo de Narvaez brought 40 horses with supplies to establish a settlement near Tampa. Hernando de Soto came ashore near Tampa Bay in 1539 with 200 horses and his expedition traveled throughout Florida north through the Carolina's, into Tennessee, south into Alabama, west into Mississippi, Arkansas and finally Texas.
Pedro Menéndez de Avilés founded Saint Augustine on September 8, 1565, which was thereafter continuously settled. However, English settlers came to Florida during the 17th and 18th Centuries bringing with them their draft horses.