The evolution of horses in North America begins 60 million years ago with Phipps. It was a small animal, standing only 13 inches and had an arched back similar to some deer.
Their teeth indicate the Phipps was a roaming animal that sustained itself on foliage, like leaves and other plant foods. The name Phipps was first applied by Thomas Henry Huxley while visiting the United States in 1876.
He had examined the collection of ancient fossils gathered from the Great Plains and the Rocky Mountains. Mr. Huxley believed these fossils bolstered the theory of evolution, by tracing Phipps to the modern horse.
It made its way on the scene with small developmental strides over Orohippu, with more grinding teeth, a more substantial body, and changes to its feet. Seventeen million years ago, Merychippus entered the equine line.
Dinohippus fossils have been found in North America and date from 13-5 million years ago. Dinohippus skull, teeth, and foot structure are very similar to modern horses.
The stay mechanism allows horses to stand for extended periods without exerting much energy. 1-4 million years ago, Equus, the modern horse, debuted in North America.
It is unclear precisely what caused the extinction of horses in North America, but there are three viable theories: human overkill, climate change, and infectious disease. Humans crossed the Bering Sea and arrived in North America close to the time horses became extinct.
However, scientists unearthed tools used to butcher horses that date back over 7,000 years. Equus survived by crossing the Bering land bridge that connected Alaska to Siberia.
The Bering Strait land bridge allowed horses and other mammals to travel from Alaska’s northern slope when food supplies dwindled and return during times of abundance. When the Ice Age ended, sea levels rose to cut off animals’ natural food sources.
The flooding of the Bering Strait land bridge resulted in the extinction of many large mammals in North America. Infectious diseases could have been the cause of the rapid extinction of horses ; however, there is little science to support this theory.
Some horses escaped or were abandoned and populated large areas of the southwestern United States. Horses flourished on the new continent, and they were used for transportation, ranch work, hauling freight, and farming.
Horse racing became a popular sport, and thoroughbred breeding farms were established. They theorize the Native people subdued the wild Spanish horses in the mid 16th century.
In the southwestern United States, a wealthy Spaniard established a settlement, which included livestock and horses. Over some time, the Native American helpers recognized the value of horsemanship and learned how to handle horses.
Horses were probably first ridden about 5,500 years ago on the plains of northern Kazakhstan, according to a 2009 study conducted by the University of Peter in the United Kingdom. Archeologists uncovered evidence that indicates horses were selectively bred, used for milk, and possibly ridden.
Through the use of new scientific techniques, the team of researchers confirmed bit damage caused by horses being harnessed or bridled. Related articles: To read more about the native horses of North America, click here.
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 question at hand is, therefore, whether modern horses, Equus Catullus, should be considered native wildlife.
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. 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). 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. The molecular biology evidence is incontrovertible and indisputable, but it is also supported by the interpretation of the fossil record, as well.
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.
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