Hagerman horse

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Hagerman horse
Temporal range: Pliocene–Early Pleistocene [1] [2]
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Equus simplicidens UMNH.jpg
Mounted skeleton of a Hagerman horse
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Perissodactyla
Family: Equidae
Genus: Equus
Species:
E. simplicidens
Binomial name
Equus simplicidens
Cope, 1892 [3]
Synonyms
  • Plesippus shoshonensisGidley, 1930 [4]

Equus simplicidens, sometimes known as the Hagerman horse or the American zebra is an extinct species in the horse family native to North America during the Pliocene and Early Pleistocene. [1] [2] It is one of the oldest and most primitive members of the genus Equus. It is the state fossil of Idaho, where its abundant remains were discovered in 1928, specifically in Hagerman, Idaho. [5] They are also known from other US states including Arizona, California, Texas, Nebraska and Kansas. [2]

Contents

Classification

Equus simplicidens skull Equus Simplicidens.jpg
Equus simplicidens skull

The Hagerman horse was given the scientific name of Plesippus shoshonensis in 1930 by a Smithsonian paleontologist named James W. Gidley [4] who led the initial excavations at Hagerman that same year.

However further study by other paleontologists determined that fossils closely resembled fossils of a primitive horse from Texas named Equus simplicidens, named by paleontologist Edward Drinker Cope in 1892. Because of this similarity, the two forms were interpreted [6] to be the same species, and since the name Equus simplicidens was the older name, it was retained following the taxonomic Principle of Priority. The Hagerman fossils represent some of the oldest widely accepted remains of the genus Equus.

Discovery

A cattle rancher named Elmer Cook discovered some fossil bones on this land in Hagerman, Idaho. In 1928, he showed them to Dr. H. T. Stearns of the U.S. Geological Survey who then passed them on to Dr. James W. Gidley at the Smithsonian Institution. Identified as bones belonging to an extinct horse, the area where the fossils were discovered, called the Hagerman Horse Quarry, was excavated and three tons of specimens were sent back to the Smithsonian in Washington, D.C.

Excavation of the fossils continued into the early 1930s. The Hagerman Horse Quarry floor grew to 5,000 square feet (460 m2) with a backwall 45 feet (14 m) high. Ultimately five nearly complete skeletons, more than 100 skulls, and forty-eight lower jaws as well as numerous isolated bones were found. Some paleontologists believed that such a large amount of fossils found in one location was because of the quarry area being a watering hole at one point. The waterhole could have been where the bones of the Hagerman horses accumulated as injured, old, and ill animals, drawn to water, died there. Other paleontologists think that an entire herd of these animals drowned attempting to ford a flooded river and were swept away in the current and ended up buried in the soft sand at the bottom.

Taxonomy

The genus placement of the species is controversial, with some authors choosing to place the species in Plesippus instead. [7] A 2019 phylogenetic analysis found it to be more closely related to living Equus than to Hippidion or Dinohippus , but outside the group containing all living equines. [8] Some authors have argued for a close relationship of Equus simplicidens with living zebras to the exclusion of other living equines, but these claims have been considered equivocal by others, who note that many "stenonine horses" from Eurasia exhibit similarities to zebras. [9]

See also

Related Research Articles

<span class="mw-page-title-main">Equidae</span> Family of hoofed mammals

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.

<span class="mw-page-title-main">Onager</span> Species of mammal

The onager, also known as hemione or Asiatic wild ass, is a species of the family Equidae native to Asia. A member of the subgenus Asinus, the onager was described and given its binomial name by German zoologist Peter Simon Pallas in 1775. Six subspecies have been recognized, two of which are extinct.

<i>Equus</i> (genus) Genus of mammals which includes horses, donkeys, and zebras

Equus is a genus of mammals in the family Equidae, which includes horses, asses, and zebras. Within the Equidae, Equus is the only recognized extant genus, comprising seven living species. Like Equidae more broadly, Equus has numerous extinct species known only from fossils. The genus originated in North America and dispersed into the Old World and South America during the Early and Middle Pleistocene. Equines are odd-toed ungulates with slender legs, long heads, relatively long necks, manes, and long tails. All species are herbivorous, and mostly grazers, with simpler digestive systems than ruminants but able to subsist on lower-quality vegetation.

<span class="mw-page-title-main">Kiang</span> Tibetan wild ass

The kiang is the largest of the Asinus subgenus. It is native to the Tibetan Plateau in Ladakh India, northern Pakistan, Tajikistan, China and northern Nepal. It inhabits montane grasslands and shrublands. Other common names for this species include Tibetan wild ass, khyang and gorkhar.

<span class="mw-page-title-main">Hagerman Fossil Beds National Monument</span> Pliocene-age site near Hagerman, Idaho

Hagerman Fossil Beds National Monument is a Pliocene-age site near Hagerman, Idaho. The 4,351-acre (17.61 km2) Monument is internationally significant because it protects one of the richest known fossil deposits from the Blancan North American Land Mammal Age. These fossils date from 3.07 million to at least 4 million years ago in age and represent at least 200 species. Hagerman is best known for having the largest known concentration of the fossil horse, Equus simplicidens. The fossil beds, including the historic Smithsonian Horse Quarry, were designated a National Natural Landmark in 1975 and was reclassified as a National Monument in 1988.

<i>Equus scotti</i> Extinct species of mammal

Equus scotti is an extinct species of horse native to Pleistocene North America.

<i>Equus lambei</i> Extinct species of horse

Equus lambei, commonly known as the Yukon horse or Yukon wild horse, is an extinct species of the genus Equus. Equus lambei ranged across North America until approximately 10,000 years ago. Based on recent examinations of the mtDNA of Equus lambei remains, scientists have concluded that E. lambei was probably much like the extinct tarpan, also known as the Eurasian wild horse, and the living Przewalski's horse. A partial carcass of Equus lambei is on display at the Yukon Beringia Interpretive Centre in Whitehorse, Yukon.

<i>Equus sivalensis</i> Extinct species of mammal

Equus sivalensis is an extinct species of large equid native to the northern Indian subcontinent. Remains date from the beginning of the Pleistocene, c. 2.58 million years ago until around 600,000 years ago, during the Middle Pleistocene. It is considered a "stenonine horse", meaning that it is more closely related to zebras and asses than true horses. Based on isotopes and teeth morphology, it is thought to have been a grazer. The later species Equus namadicus from the same region has sometimes been suggested to be a synonym due to their similar teeth morphology.

<i>Equus namadicus</i> Extinct species of mammal

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.

<i>Hippidion</i> Extinct genus of mammals

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.

<span class="mw-page-title-main">Evolution of the horse</span>

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 Hagerman Horse Quarry is a paleontological site containing the largest concentration of Hagerman horse fossils yet found. The quarry is within Hagerman Fossil Beds National Monument, located west of Hagerman, Idaho, USA, at the geographic division of the Snake River Plain. The Hagerman Horse Quarry is an integral part of the monument and is located on the northern flank of Fossil Gulch in the northern portion of the monument.

<i>Stephanorhinus</i> Extinct genus of rhinoceros

Stephanorhinus is an extinct genus of two-horned rhinoceros native to Eurasia and North Africa that lived during the Late Pliocene to Late Pleistocene. Species of Stephanorhinus were the predominant and often only species of rhinoceros in much of temperate Eurasia, especially Europe, for most of the Pleistocene. The last two species of Stephanorhinus – Merck's rhinoceros and the narrow-nosed rhinoceros – went extinct during the last glacial period.

<i>Equus neogeus</i> Extinct species of equine native to South America

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.

<span class="mw-page-title-main">Paleontology in Idaho</span> Paleontological research in the U.S. state of Idaho

Paleontology in Idaho refers to paleontological research occurring within or conducted by people from the U.S. state of Idaho. The fossil record of Idaho spans much of the geologic column from the Precambrian onward. During the Precambrian, bacteria formed stromatolites while worms left behind trace fossils. The state was mostly covered by a shallow sea during the majority of the Paleozoic era. This sea became home to creatures like brachiopods, corals and trilobites. Idaho continued to be a largely marine environment through the Triassic and Jurassic periods of the Mesozoic era, when brachiopods, bryozoans, corals, ichthyosaurs and sharks inhabited the local waters. The eastern part of the state was dry land during the ensuing Cretaceous period when dinosaurs roamed the area and trees grew which would later form petrified wood.

<span class="mw-page-title-main">Horses in the United States</span>

Horses have been an important component of American life and culture since before the founding of the nation. In 2023, there were an estimated 6.65 million horses in the United States, with 1.5 million horse owners, 25 million citizens that participate in horse related activities, 12 million citizens that spectate at horse events, and 4.6 million citizens involved in businesses related to horses. There are an estimated 82,000 feral horses that roam freely in the wild in certain parts of the country, mostly in the Western United States.

<i>Equus stenonis</i> Extinct species of mammal

Equus stenonis is an extinct species of equine that lived in Western Eurasia during the Early Pleistocene epoch.

The giant horse is an extinct species of horse which lived in North America.

<i>Equus lenensis</i> Extinct species of mammal

Equus lenensis, the Lena horse, is an extinct species of horse from the Late Pleistocene and Holocene of Siberia, Some sources have considered it a subspecies of the wild horse.

References

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  2. 1 2 3 Cirilli, Omar; Machado, Helena; Arroyo-Cabrales, Joaquin; Barrón-Ortiz, Christina I.; Davis, Edward; Jass, Christopher N.; Jukar, Advait M.; Landry, Zoe; Marín-Leyva, Alejandro H.; Pandolfi, Luca; Pushkina, Diana; Rook, Lorenzo; Saarinen, Juha; Scott, Eric; Semprebon, Gina (24 August 2022). "Evolution of the Family Equidae, Subfamily Equinae, in North, Central and South America, Eurasia and Africa during the Plio-Pleistocene". Biology. 11 (9): 1258. doi: 10.3390/biology11091258 . ISSN   2079-7737. PMC   9495906 . PMID   36138737.
  3. Cope, E. D. (1892). "A Contribution to the Vertebrate Paleontology of Texas". Proceedings of the American Philosophical Society. 30 (137): 124–125. JSTOR   983215 .
  4. 1 2 J.W. Gidley (1930) A new Pliocene horse from Idaho. Journal of Mammalogy 11: 300-303 JSTOR   1374150 doi : 10.2307/1374150
  5. Idaho: Equus simplicidens (state fossil). StateFossils.com [ dead link ]
  6. D.E. Savage (1951) late Cenozoic vertebrates of the San Francisco Bay region. University of California Bulletin of the Department of Geological Sciences 28: 215-314
  7. Orlando, Ludovic; Ginolhac, Aurélien; Zhang, Guojie; Froese, Duane; Albrechtsen, Anders; Stiller, Mathias; Schubert, Mikkel; Cappellini, Enrico; Petersen, Bent; Moltke, Ida; Johnson, Philip L. F.; Fumagalli, Matteo; Vilstrup, Julia T.; Raghavan, Maanasa; Korneliussen, Thorfinn (2013-07-04). "Recalibrating Equus evolution using the genome sequence of an early Middle Pleistocene horse". Nature. 499 (7456): 74–78. Bibcode:2013Natur.499...74O. doi:10.1038/nature12323. ISSN   0028-0836. PMID   23803765. S2CID   4318227.
  8. Cirilli, Omar; Pandolfi, Luca; Rook, Lorenzo; Bernor, Raymond L. (2021-05-12). "Evolution of Old World Equus and origin of the zebra-ass clade". Scientific Reports. 11 (1): 10156. Bibcode:2021NatSR..1110156C. doi:10.1038/s41598-021-89440-9. ISSN   2045-2322. PMC   8114910 . PMID   33980921.
  9. O’Brien, Kaedan; Tryon, Christian A.; Blegen, Nick; Kimeu, Boniface; Rowan, John; Faith, J. Tyler (March 2021). "First appearance of Grévy's zebra (Equus grevyi), from the Middle Pleistocene Kapthurin Formation, Kenya, sheds light on the evolution and paleoecology of large zebras". Quaternary Science Reviews. 256: 106835. Bibcode:2021QSRv..25606835O. doi:10.1016/j.quascirev.2021.106835. S2CID   233638447.

Further reading