Hagerman horse

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Hagerman horse
Temporal range: Pliocene–Early Pleistocene [1]
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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 [2]
Synonyms
  • Plesippus shoshonensisGidley, 1930 [3]

Equus simplicidens, also known as the Hagerman horse and American zebra, is an extinct species of equine native to North America during the Pliocene and Early Pleistocene. [1] It is one of the oldest and most primitive members of the genus Equus. It is the state fossil of Idaho, where abundant remains of the species were discovered near the town of Hagerman in 1928.

Contents

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. [4]

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. [4] Gidley 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. [4] A study by H. Gregory McDonald in 1996 alternatively suggested based on the age distribution of remains at the quarry, which span from newborns to adults, that a herd died in a single catastrophic event, perhaps attempting to cross a swelled/flooded river. [5]

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 [3] 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. [7]

The genus placement of the species is controversial, with some authors choosing to place the species in Plesippus instead. [8] 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. [9]

Evolution

The earliest remains of Equus simplicidens date to the Pliocene, around 4.1-3.2 million years years ago. [10] [11] Equus simplicidens has been suggested to be the ancestor of the Eurasian "stenonine" equines such as Equus stenonis , which first appeared in Eurasia at the beginning of the Pleistocene, around 2.6 million years ago, which have been proposed to be the ancestors of living zebras and asses. [7] [10] The youngest fossils of E. simplicidens date to the Irvingtonian. [12]

Description

The body mass of adult Equus simplicidens been estimated at around 300–400 kilograms (660–880 lb) in life, comparable to a zebra. [10] The overall form of the skull has been considered comparable to those of zebras, though the dental morphology is more primitive. [12] The vomer bone of the skull is noticeably elongate, with the preorbital fossa being relatively large. The ramus of the mandible is angled posteriorly. [7]

Distribution

Remains of Equus simplicidens are known from across Western and Central North Amerrica, including Idaho, Arizona, California, Texas, Nebraska and Kansas, southwards to Mexico. [12]

Ecology

Equus simplicidens is thought to have had a highly abrasive almost exclusively grazing based diet, similar to that of modern equines, particularly zebras. [10] [13] The species is suggested to have had a herding social structure similar to living Equus, perhaps lead by a dominant harem stallion male similar to living horses. [5]

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 more than 50 million years ago, in the Eocene epoch, 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. It is more specifically grouped within the superfamily Equoidea, the only other family being the extinct Palaeotheriidae.

<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.

<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.

<span class="mw-page-title-main">History of the horse in the Indian subcontinent</span>

The horse has been present in the Indian subcontinent from at least the middle of the second millennium BC, more than two millennia after its domestication in Central Asia. The earliest uncontroversial evidence of horse remains on the Indian Subcontinent date to the early Swat culture. While horse remains and related artifacts have been found in Late Harappan sites, indicating that horses may have been present at Late Harappan times, horses did not play an essential role in the Harappan civilisation, in contrast to the Vedic period. The importance of the horse for the Indo-Aryans is indicated by the Sanskrit word Ashva, "horse," which is often mentioned in the Vedas and Hindu scriptures.

<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", related to species like the European Equus stenonis, 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>Megahippus</i> Extinct genus of mammals

Megahippus is an extinct genus of large Anchitheriine horses found throughout the southern portion of the United States during the middle Miocene. The animal represents one of the latest low-crowned horses, overlapping in time with more derived high-crowned horses.

<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">Hipparionini</span> Extinct tribe of mammals

Hipparionini is a tribe of three-toed horses in the subfamily Equinae. They had body forms similar to modern equines, with high-crowned teeth. They first appeared in North America during the Early Miocene around 17 million years ago, before migrating into the Old World around 11.4-11.0 million years ago. The youngest species date to the Early Pleistocene, becoming extinct following the arrives of modern equines of the genus Equus to the Old World.

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

Eurygnathohippus is an extinct genus of hipparionine horse. The majority of known fossils of members of this genus were discovered in Africa, where members of this genus lived during the late Miocene to Pleistocene interval. Fossils of Eurygnathohippus were also reported from the late Pliocene sediments of the Potwar Plateau in Pakistan and the Siwalik Hills in northwest India.

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

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

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

Equus altidens is an extinct species of equine native to western Eurasia including Europe during the Early Pleistocene to early Middle Pleistocene.

Equus major is an extinct species of large equine native to Europe during the Early Pleistocene epoch.

Equus suessenbornensis is an extinct species of large equine native to Western Eurasia, including Europe, during the Early Pleistocene to early Middle Pleistocene.

References

  1. 1 2 Skinner, M.F. (1972). "Order Perissodactyla". In Skinner, M.F.; Hibbard, C.W. (eds.). Early Pleistocene Preglacial and Glacial Rocks and Faunas of North-Central Nebraska. Vol. 148. New York: American Museum of Natural History. pp. 117–125. S2CID   129067309.
  2. ↑ Cope, E. D. (1892). "A Contribution to the Vertebrate Paleontology of Texas". Proceedings of the American Philosophical Society. 30 (137): 124–125. JSTOR   983215 .
  3. 1 2 J.W. Gidley (1930) A new Pliocene horse from Idaho. Journal of Mammalogy 11: 300-303 JSTOR   1374150 doi : 10.2307/1374150
  4. 1 2 3 McDonald, H. Gregory (October 1993). "More Than Just Horses Hagerman Fossil Beds: Hagerman, Idaho". Rocks & Minerals. 68 (5): 322–326. doi:10.1080/00357529.1993.9926562. ISSN   0035-7529.
  5. 1 2 McDonald, H. Gregory (1996-12-31), "Population structure of the late Pliocene (Blancan) zebra Equus simplicidens (Perissodactyla: Equidae) from the Hagerman Horse Quarry, Idaho", Palaeoecology and Palaeoenvironments of Late Cenozoic Mammals, University of Toronto Press, pp. 134–155, doi:10.3138/9781487574154-010, ISBN   978-1-4875-7415-4 , retrieved 2024-12-17
  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. 1 2 3 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.
  8. ↑ 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.
  9. ↑ 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.
  10. 1 2 3 4 Cirilli, Omar; Semprebon, Gina M.; Bernor, Raymond L. (September 2024). "Paleodietary reconstruction of Equus simplicidens from the Hagerman Horse Quarry (Idaho, USA) highlights high abrasive habits in North American fossil equids during the Pliocene". Palaeogeography, Palaeoclimatology, Palaeoecology. 650: 112376. Bibcode:2024PPP...65012376C. doi:10.1016/j.palaeo.2024.112376.
  11. ↑ Rook, Lorenzo; Bernor, Raymond L.; Avilla, Leonardo S.; Cirilli, Omar; Flynn, Lawrence; Jukar, Advait; Sanders, William; Scott, Eric; Wang, Xiaoming (2019-07-25). "Mammal Biochronology (Land Mammal Ages) Around the World From Late Miocene to Middle Pleistocene and Major Events in Horse Evolutionary History". Frontiers in Ecology and Evolution. 7. doi: 10.3389/fevo.2019.00278 . hdl: 2158/1168180 . ISSN   2296-701X.
  12. 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.
  13. ↑ Semprebon, Gina M.; Rivals, Florent; Solounias, Nikos; Hulbert, Richard C. (January 2016). "Paleodietary reconstruction of fossil horses from the Eocene through Pleistocene of North America". Palaeogeography, Palaeoclimatology, Palaeoecology. 442: 110–127. Bibcode:2016PPP...442..110S. doi:10.1016/j.palaeo.2015.11.004.

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