Skip to main content
Select Source:

Equidae

Equidae (horses; order Perissodactyla, suborder Hippomorpha) A family that includes the modern horses, asses, and zebras (all of which are placed in a single genus Equus, divided into six or seven species, depending on the classification used) and many extinct forms, the earliest being known from the late Palaeocene. Sufficient of these are believed to be ancestral to modern equids for the evolution of the family to have been traced in considerable detail. The domestic horse (E. caballus) is probably not descended from the only true living wild horse, Przewalski’s horse (E. ferus przewalskii), but from a progenitor closely related to it. Modern equids are adapted for rapid movement: they have a short humerus and femur, and a long radius and tibia; the ulna is reduced and fused to the radius, and the fibula is also reduced. Only the third toe is developed. All the incisors are present, canines are present in males, and the cheek teeth are hypsodont, with complex grinding surfaces. The brain is large and senses of sight, smell, touch, and hearing are highly developed. Equids are migratory grassland animals, graze mainly on grasses, and have complex social organization. Wild species are found in Africa and parts of central and western Asia. The horses are first represented in the fossil record by Hyracotherium, which diverged from a condylarth predecessor in the Palaeocene. Numerous evolutionary lines subsequently appeared from this fox-sized prototype. Most of the evolutionary advances occurred in the New World, although the Equidae were to survive the Pleistocene only in the Old World. The conquistadores reintroduced horses to the Americas in the 16th century.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Equidae." A Dictionary of Zoology. . Encyclopedia.com. 17 Feb. 2018 <http://www.encyclopedia.com>.

"Equidae." A Dictionary of Zoology. . Encyclopedia.com. (February 17, 2018). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/equidae-0

"Equidae." A Dictionary of Zoology. . Retrieved February 17, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/equidae-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Equidae

Equidae (horses; order Perissodactyla) Family that includes the modern horses, asses, and zebras (all of which are placed in a single genus Equus), and many extinct forms. Sufficient of these are believed to be ancestral to modern equids for the evolution of the family to have been traced in considerable detail. The horses are first represented in the fossil record by Hyracotherium (‘Eohippus’) which diverged from a condylarth predecessor in the Palaeocene. Numerous evolutionary lines subsequently appeared from this fox-sized prototype. Most of the evolutionary advances occurred in the New World, although the Equidae were to survive the Pleistocene only in the Old World. The conquistadores reintroduced horses to the Americas in the 16th century. The domestic horse (E. caballus) is probably not descended from the only true living wild horse, Przewalski's horse (E. ferus przewalskii), but from a progenitor closely related to it.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Equidae." A Dictionary of Earth Sciences. . Encyclopedia.com. 17 Feb. 2018 <http://www.encyclopedia.com>.

"Equidae." A Dictionary of Earth Sciences. . Encyclopedia.com. (February 17, 2018). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/equidae

"Equidae." A Dictionary of Earth Sciences. . Retrieved February 17, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/equidae

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

equids

equids See EQUIDAE.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"equids." A Dictionary of Zoology. . Encyclopedia.com. 17 Feb. 2018 <http://www.encyclopedia.com>.

"equids." A Dictionary of Zoology. . Encyclopedia.com. (February 17, 2018). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/equids

"equids." A Dictionary of Zoology. . Retrieved February 17, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/equids

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.