Equidae


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Equidae

[′ēk·wə‚dē]
(vertebrate zoology)
A family of perissodactyl mammals in the superfamily Equoidea, including the horses, zebras, and donkeys.

Equidae

 

a family of the order Perissodactyla. It comprises three subfamilies with approximately 20 genera, including extinct genera (such as Hyracotherium, Anchitherium, Mesohippus, Miohippus, Merychippus, Hipparion, and Pliohippus) and the only surviving genus, Equus.

The family comprises animals varying greatly in appearance and structure. With the exception of the most ancient (Eocene) representatives, equids are well-proportioned animals, with long legs and a very developed large third toe encased in a hoof; the second and fourth toes are greatly reduced (they are absent in modern equids). The facial part of the skull is greatly elongated. The cheek teeth are hypsodont and grow as they wear down. The equids evolved so as to adapt to fast running in open spaces and eating coarse vegetation. During the evolutionary process, the legs lengthened, the joints straightened, the middle toe enlarged, and the side toes gradually reduced. The face lengthened as the molars grew larger, and the premolars acquired a molar-like appearance and a complex folded chewing surface.

The history of the family Equidae has been well studied in North America, where they lived from the early Eocene epoch to the late Pliocene epoch. In the eastern hemisphere, in different geological periods there existed representatives of the family that were not linked to one another evolutionarily. The ancestors of the modern equids came to the eastern hemisphere from North America in the late Pliocene epoch, and in different parts of their vast area of distribution gave rise to different groups of modern equids. The history of the family’s development studied in detail by V. O. Kovalevskii is a classic example of research into the specific evolutionary paths of a large group of animals.

REFERENCES

Kovalevskii, V. O. Sobranie nauchnykh trudov, vol. 2. Moscow, 1956.
Osnovy paleontologii: Mlekopitaiushchie. Moscow, 1962.
Simpson, G. G. Horses. New York, 1951.

B. A. TROFIMOV

References in periodicals archive ?
Cormohipparion n gen (Mammalia, Equidae) from the North American Miocene (Barstovian-Clarendonian).
Adaptive explanation in socioecology: Lessons from the Equidae. Biological Review 75:1-20.
The CFT for glanders is so far the only officially recognized serological laboratory test for international trade of equidae and remains the preferred diagnostic tool in eradication programme.
Five same samples were digested in the same condition; the marker peptides in these five same samples could be detected; the selected ions chromatograms for the five samples from the family Equidae are shown in Figure 1.
It maintained that the directive authorises a reduced VAT rate for live animals "normally" intended for use in the preparation of foodstuffs and for transactions related to equidae, particularly horses, for agricultural, forestry or fishery activities, to the extent that they constitute deliveries or services intended for use in agricultural production.
Num Num Taxon Tooth Locality SDSM 07887 AP N/A Equidae M2 V5314 SDSM 6748 N/A Neohipparion P3 V5314 SDSM 5330 N/A c.f Protohipppus P3 V5314 SDSM 6746 N/A Pliohippus P2 V5314 SDSM 727 N/A Pseudhipparion P4 V5314 SDSM 579A N/A c.f.
* MACFADDEN, B.J., Fossil Horses, Systematics, Paleobiology and Evolution of the Family Equidae. New York: Cambridge University Press, 362 pp., 1992.
Some of Crute's recent exhibitions include a group show at the Florida Thoroughbred Breeders' and Owners' Association and at Equidae Gallery in Saratoga Springs, N.Y.; a two-artist exhibit at Gallery Central in Hot Springs, Ark.; and a solo exhibit at Fayette Gallery in Lexington, Ky.
However, a study of the macro-vertebrate fossil assemblage revealed a community of grazers, dominated by six species of Equis (Equidae), three of which are only known from the Black Belt and the Great Plains, and insect studies revealed the presence of an endemic, flightless ground beetle, Cyclotrechelus hyperpiformis Freitag (Coleoptera: Carabidae), whose most closely related species occurs in Texas and the Great Plains, and the local abundance of the moth, Ceratomia hageni Grt.
As a result of the last Venezuelan equine encephalitis epizoodemic (VEE), happened in Venezuela during 1995 that affected equidae and humans of Zulia State and another states of the country, the reinforcement of epidemiological surveillance programs for the prevention and control of equine encephalitis was stablished.
It is somewhat striking that the Sorrel Nag appears to have no vegetarian qualms about 'handling' a lump of decomposing meat; a certain repugnance might have been expected, especially as it had been torn from the limb of an unfortunate member of a most closely related species of the horse family (Equidae).