Equus neogeus | |
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Skull | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Perissodactyla |
Family: | Equidae |
Genus: | Equus |
Species: | †E. neogeus |
Binomial name | |
†Equus neogeus Lund, 1840 | |
Synonyms | |
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Equus neogeus is an extinct species of equine native to South America during the Pleistocene. It was formerly thought to be several distinct species within the subgenus Amerhippus, but was later shown to be a single morphologically variable species. It is thought to be closely related to true horses.
While they have formerly been referred to as belonging to 5 separate species, this has been revised down into three, [1] and more recently a single, morphologically variable species Equus neogeus. [2] [3] Some authors continue to recognise three species, restricting Equus neogeus to large-sized individuals spanning from the Pampas to Northeast Brazil, while separating the smaller Equus andium for populations in the northern-central Andes, and Equus insulatus for medium-sized animals spanning from Bolivia to Venezuela. These authors suggest that E. insulatus was the ancestor of the other species. [4] Historically, South American Equus species were placed in the subgenus Amerhippus, but this has subsequently been questioned. [4] A 2008 study of mitochondrial DNA fragments of a specimen of E. neogeus found it to be nested within mitochondrial lineages of E. caballus, [5] however, later studies suggested that this result required more specimens to be analysed for confirmation. [6] A close relationship to caballine horses was also supported by a 2019 morphological analysis study. [7]
Equus neogeus measured roughly 1.5 m (4.9 ft) tall and weighed approximately 400 kg (880 lb). [8]
They were one of two groups of equines in South America, alongside Hippidion . [9] Fossils have been recovered from the Tarija Formation of Bolivia, the Serranía del Perijá in Venezuela, the Chiu-Chiu Formation of Chile, the Sabana Formation of the Bogotá savanna in Colombia, [10] and from various locations in Ecuador. [8] Equus first appeared in South America during the late Early Pleistocene-earliest Middle Pleistocene, around 1 to 0.8 million years ago, based on remains found near Tarija, Bolivia. [11]
A 2019 study suggested that Equus neogeus specimens from Uruguay were primarily grazers that fed on both C4 and C3 grasses in prairies and open woodlands. [12]
Equus neogeus became extinct at the end of the Late Pleistocene as part of the end-Pleistocene extinctions, along with the vast majority of other large mammals in South America. [13] The youngest remains date to approximately 11,700 years Before Present (BP), in Río Quequén Salado, in the southwest of Buenos Aires province, Argentina. [11] The extinctions followed human arrival to the Americas, and several sites show evidence of human interaction with Equus neogeus, which may have been a factor in its extinction. [14] At the Paso Otero 5 site in the Pampas of northeast Argentina, Fishtail points are associated with burned bones of Equus neogeus and other extinct megafauna. The bones appear to have been deliberately burned as a source of fuel. Due to the poor preservation of the bones there is no clear evidence of human modification. [15] At the Taguatagua 3 in central Chile, dating to around 12,440–12,550 years BP, a first phalanx of Equus was found near a hearth, alongside the remains of other megafuna, including the much more abundant remains of gomphotheres (elephant relatives). [16] At the Arroyo Seco 2 site in the Argentinian Pampas, which has multiple episodes of human activity dating to between 14,782–11,142 cal yr BP remains of Equus neogeus (alongside those of other megafauna) are associated with human artifacts and exhibit fracture marks indicative of butchery. [14] [17]
Equidae is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. The family evolved around 50 million years ago from a small, multi-toed ungulate into larger, single-toed animals. All extant species are in the genus Equus, which originated in North America. Equidae belongs to the order Perissodactyla, which includes the extant tapirs and rhinoceros, and several extinct families.
Megatherium is an extinct genus of ground sloths endemic to South America that lived from the Early Pliocene through the end of the Pleistocene. It is best known for the elephant-sized type species Megatherium americanum, native to the Pampas through southern Bolivia during the Pleistocene. Various other species belonging to the subgenus Pseudomegatherium ranging in size comparable to considerably smaller than M. americanum are known from the Andean region.
In zoology, megafauna are large animals. The precise definition of the term varies widely, though a common threshold used in paleontology is approximately 45 kilograms (99 lb), with other thresholds as low as 10 kilograms (22 lb) or as high as 1,000 kilograms (2,200 lb). Large body size is generally associated with other traits, such as having a slow rate of reproduction, and in large herbivores, reduced or negligible adult mortality from being killed by predators.
Gomphotheres are an extinct group of proboscideans related to modern elephants. They were widespread across Afro-Eurasia and North America during the Miocene and Pliocene epochs and dispersed into South America during the Pleistocene as part of the Great American Interchange. Gomphotheres are a paraphyletic group that is ancestral to Elephantidae, which contains modern elephants, as well as Stegodontidae. While most famous forms such as Gomphotherium had long lower jaws with tusks, which is the ancestral condition for the group, some later members developed shortened (brevirostrine) lower jaws with either vestigial or no lower tusks, looking very similar to modern elephants, an example of parallel evolution, which outlasted the long-jawed gomphotheres. By the end of the Early Pleistocene, gomphotheres became extinct in Afro-Eurasia, with the last two genera, Cuvieronius ranging from southern North America to western South America, and Notiomastodon having a wide range over most of South America until the end of the Pleistocene around 12,000 years ago, when they became extinct following the arrival of humans.
Toxodon is an extinct genus of large ungulate native to South America from the Late Miocene to early Holocene epochs. Toxodon is a member of Notoungulata, an order of extinct South American native ungulates distinct from the two living ungulate orders that had been indigenous to the continent for over 60 million years since the early Cenozoic, prior to the arrival of living ungulates into South America around 2.5 million years ago during the Great American Interchange. Toxodon is a member of the family Toxodontidae, which includes medium to large sized herbivores. Toxodon was one of the largest members of Toxodontidae and Notoungulata, with Toxodon platensis having an estimated body mass of 1,000–1,200 kilograms (2,200–2,600 lb).
The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy, also known as the Upper Pleistocene from a stratigraphic perspective. It is intended to be the fourth division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently defined as the time between c. 129,000 and c. 11,700 years ago. The late Pleistocene equates to the proposed Tarantian Age of the geologic time scale, preceded by the officially ratified Chibanian. The beginning of the Late Pleistocene is the transition between the end of the Penultimate Glacial Period and the beginning of the Last Interglacial around 130,000 years ago. The Late Pleistocene ends with the termination of the Younger Dryas, some 11,700 years ago when the Holocene Epoch began.
Equus scotti is an extinct species of horse native to Pleistocene North America.
The wild horse is a species of the genus Equus, which includes as subspecies the modern domesticated horse as well as the endangered Przewalski's horse. The European wild horse, also known as the tarpan, that went extinct in the late 19th or early 20th century has previously been treated as the nominate subspecies of wild horse, Equus ferus ferus, but more recent studies have cast doubt on whether tarpans were truly wild or if they actually were feral horses or hybrids.
Doedicurus is an extinct genus of glyptodont from North and South America containing one species, D. clavicaudatus. Glyptodonts are a member of the family Chlamyphoridae, which also includes some modern armadillo species, and they are classified in the superorder Xenarthra alongside sloths and anteaters. Being a glyptodont, it was a rotund animal with heavy armor and a carapace. Averaging at an approximate 1,400 kg (3,100 lb), it was one of the largest glyptodonts to have ever lived. Though glyptodonts were quadrupeds, large ones like Doedicurus may have been able to stand on two legs like other xenarthrans. It notably sported a spiked tail club, which may have weighed 40 or 65 kg in life, and it may have swung this in defense against predators or in fights with other Doedicurus at speeds of perhaps 11 m/s.
Cuvieronius is an extinct New World genus of gomphothere which ranged from southern North America to western South America during the Pleistocene epoch. Among the last gomphotheres, it became extinct at the end of the Pleistocene, approximately 12,000 years ago, following the arrival of humans to the Americas.
Equus namadicus is a prehistoric equid, known from remains dating to the Middle and Late Pleistocene from across the Indian subcontinent, with its last dated records being approximately 29-14,000 years ago. It is considered a "stenonine horse", meaning that it is probably more closely related to zebras and asses than true horses. It is relatively large in size. It is very similar to the earlier Equus sivalensis, also from the Indian subcontinent, from which it only differs in size and in subtle aspects of dental anatomy, and it has sometimes been suggested to be a synonym of it.
Hippidion is an extinct genus of equine that lived in South America from the Late Pliocene to the end of the Late Pleistocene (Lujanian), between 2.5 million and 11,000 years ago. They were one of two lineages of equines native to South America during the Pleistocene epoch, alongside Equus (Amerhippus) neogeus.
The evolution of the horse, a mammal of the family Equidae, occurred over a geologic time scale of 50 million years, transforming the small, dog-sized, forest-dwelling Eohippus into the modern horse. Paleozoologists 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, before being reintroduced in the 15th century.
Plesippus is a genus of extinct horse from the Pleistocene of North America. Although commonly seen as a subgenus of Equus recent cladistic analysis considers it a distinct genus.
The Late Pleistocene to the beginning of the Holocene saw numerous extinctions of predominantly megafaunal animal species, which resulted in a collapse in faunal density and diversity across the globe. The extinctions during the Late Pleistocene are differentiated from previous extinctions by the widespread absence of ecological succession to replace these extinct megafaunal species, and the regime shift of previously established faunal relationships and habitats as a consequence. The timing and severity of the extinctions varied by region and are thought to have been driven by varying combinations of human and climatic factors. Human impact on megafauna populations is thought to have been driven by hunting ("overkill"), as well as possibly environmental alteration. The relative importance of human vs climatic factors in the extinctions has been the subject of long-running controversy.
Glyptodon is a genus of glyptodont, an extinct group of large, herbivorous armadillos, that lived from the Pliocene, around 3.2 million years ago, to the early Holocene, around 11,000 years ago, in Brazil, Uruguay, Paraguay, Bolivia, Peru, Argentina, and Colombia. It is one of, if not the, best known genus of glyptodont. Glyptodon has a long and storied past, being the first named extinct cingulate and the type genus of the subfamily Glyptodontinae. Fossils of Glyptodon have been recorded as early as 1814 from Pleistocene aged deposits from Uruguay, though many were incorrectly referred to the ground sloth Megatherium by early paleontologists.
Haringtonhippus is an extinct genus of equine from the Pleistocene of North America The genus is monospecific, consisting of the species H. francisci, initially described in 1915 by Oliver Perry Hay as Equus francisci. Members of the genus are often referred to as stilt-legged horses, in reference to their slender distal limb bones, in contrast with those of contemporary "stout legged" caballine true horses.
Eutatus is an extinct genus of large armadillos of the family Chlamyphoridae. It was endemic to South America from the Early Miocene to Late Pleistocene, living from 17.5 Ma-11,000 years ago, with possible survival into the early Holocene and existing for approximately 17.49 million years. Based on carbon isotope ratios, it is thought to have been an herbivore that fed on grasses.
Notiomastodon is an extinct genus of gomphothere proboscidean, endemic to South America from the Pleistocene to the beginning of the Holocene. Notiomastodon specimens reached a size similar to that of the modern Asian elephant, with a body mass of 3-4 tonnes. Like other brevirostrine gomphotheres such as Cuvieronius and Stegomastodon, Notiomastodon had a shortened lower jaw and lacked lower tusks, unlike more primitive gomphotheres like Gomphotherium.