Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
Related to Equidae: Equids


(vertebrate zoology)
A family of perissodactyl mammals in the superfamily Equoidea, including the horses, zebras, and donkeys.



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.


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


References in periodicals archive ?
As mentioned above, the three conceptual categories we wish to concentrate on presently are EQUIDAE, (4) CANIDAE and FELIDAE.
Horse owners can safely achieve any daily caloric requirement by utilizing good quality forage or pasture combined with either Equidae formula.
ACAD Director Professor Alan Cooper said that despite an excellent fossil record of equidae, many gaps remain in our knowledge of its evolution.
The response to our initial rollout of Equidae from distributors and retailers has been overwhelmingly positive," said Mike DeNunzio of the Canidae Small and Large Animal Division.
Remains of Equidae are the most abundant large animal skeletal elements.
Framework Agreement surveillance services, control and eradication of animal diseases, those transmitted from animals to humans, animal protection and environmental protection, the identification and registration of bovine animals, swine, cattle, goats and equidae and their movement, and correcting any errors or nonconformities arising from failure to observe the registration or recording errors.
The Equidae line of horse feed will be guaranteed and marketed by Canidae Pet Foods, a trusted brand for over 14 years, and is a 100% extruded horse feed designed for optimal nutrition and superior digestibility for all classes and age groups of horse.
herons and egrets) serve as virus reservoirs, but the virus regularly spills over into pigs, members of the family of equidae (e.
most of the animals (deer, equidae, bovidae, megaceros) were brought whole onto the site where they were processed and consumed,
However, active infection has never been conclusively documented in any member of the Equidae (2-6).
Fossil Horses--Systematics, Paleobiology, and Evolution of the Family Equidae.