The Hagerman horse (''Equus simplicidens''), also called the Hagerman zebra or the American zebra, was a

North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the ...

species of

equid Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. All extant species are in the genus '' Equus' ...

from the

Pliocene epoch The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Pleistocene epoch The Pleistocene ( , often referred to as the '' Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed i ...

. It was one of the oldest horses of the genus ''Equus'' and was discovered in 1928 in

Hagerman, Idaho Hagerman is a city in Gooding County, Idaho, United States. The population was 872 at the 2010 census, up from 656 in 2000. The area is noted for its fossil beds and the Thousand Springs of the Eastern Snake Plain Aquifer. Hagerman is home t ...

. It is the

state fossil Most American states have made a state fossil designation, in many cases during the 1980s. It is common to designate one species in which fossilization has occurred, rather than a single specimen, or a category of fossils not limited to a single ...

Idaho Idaho ( ) is a U.S. state, state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Monta ...

.Idaho: ''Equus simplicidens'' (state fossil).
StateFossils.com

Classification

The Hagerman horse was given the scientific name of ''Plesippus shoshonensis'' in 1930 by a Smithsonian

paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

named James W. Gidley (1930) A new Pliocene horse from Idaho. ''Journal of Mammalogy'' 11: 300-303 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 Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American zoologist, paleontologist, comparative anatomist, herpetologist, and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interes ...

in 1892. Because of this similarity, the two forms were interpreted (1951) late Cenozoic vertebrates of the San Francisco Bay region. ''University of California Bulletin of the Department of Geological Sciences'' 28: 215-314 to be the same species, and since the name ''Equus simplicidens'' was the older name, it was retained following the taxonomic

Principle of Priority 270px, '' valid name. Priority is a fundamental principle of modern botanical nomenclature and zoological nomenclature. Essentially, it is the principle of recognising the first valid application of a name to a plant or animal. There are two a ...

. 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 The Smithsonian Institution ( ), or simply the Smithsonian, is a group of museums and education and research centers, the largest such complex in the world, created by the U.S. government "for the increase and diffusion of knowledge". Found ...

. Identified as bones belonging to an extinct horse, the area where the fossils were discovered, called the

Hagerman Horse Quarry The Hagerman Horse Quarry is a paleontological site containing the largest concentration of Hagerman horse (''Equus simplicidens'') fossils yet found. The quarry is within Hagerman Fossil Beds National Monument, located west of Hagerman, Idaho, US ...

, 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 with a backwall 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.

Overview

The Hagerman horse first appeared about 3.5 million years ago. It was approximately tall at the shoulder. It weighed between . An average Hagerman horse was about the same size as an

Arabian horse The Arabian or Arab horse ( ar, الحصان العربي , DMG ''ḥiṣān ʿarabī'') is a breed of horse that originated on the Arabian Peninsula. With a distinctive head shape and high tail carriage, the Arabian is one of the most easily ...

. It also was relatively stocky with a straight shoulder and thick neck, like a zebra, and a short, narrow, donkey-like skull. The horse probably lived in grasslands and floodplains, which is what Hagerman was like between three and four million years ago. Native North American horses became extinct about 10,000 years ago, at the same time as many other large-bodied species of the period.

References

The Hagerman Horse Quarry

Dr. Greg McDonald

Classification

Discovery

Overview

See also

References

Further reading