The ergot is a small

callosity A callosity is another name for callus, a piece of skin that has become thickened as a result of repeated contact and friction. Primates All Old World monkeys, gibbons, and some chimpanzees have pads on their rears known as ischial callosities. ...

(''Calcar metacarpeum and Calcar metatarseum)'' on the underside of the

fetlock Fetlock is the common name in horses, large animals, and sometimes dogs for the metacarpophalangeal and metatarsophalangeal joints (MCPJ and MTPJ). Although it somewhat resembles the human ankle in appearance, the joint is homologous to the ba ...

of a

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...

or other

equine Equinae is a subfamily of the family Equidae, which have lived worldwide (except Indonesia and Australia) from the Hemingfordian stage of the Early Miocene (16 million years ago) onwards. They are thought to be a monophyletic grouping.B. J. Ma ...

. Some equines have them on all four fetlocks; others have few or no detectable ergots. In horses, the ergot varies from very small to the size of a pea or bean, larger ergots occurring in horses with "

feather Feathers are epidermal growths that form a distinctive outer covering, or plumage, on both avian (bird) and some non-avian dinosaurs and other archosaurs. They are the most complex integumentary structures found in vertebrates and a premie ...

" – long hairs on the lower legs. In some other equines, the ergot can be as much as in diameter. ''Ergot'' comes from the French word for ''rooster's spur''.Clothier, Jane, ''The Ergot, p.15, ''Equine News'' Autumn 2010

Evolution

Like the

chestnut The chestnuts are the deciduous trees and shrubs in the genus ''Castanea'', in the beech family Fagaceae. They are native to temperate regions of the Northern Hemisphere. The name also refers to the edible nuts they produce. The unrel ...

, the ergot is thought to be a

vestige Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...

of some part of the ancestral foot of the multi-toed Equidae, the ergot corresponding to the sole pad of other

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...

members of Perissodactyla, such as the

tapir Tapirs ( ) are large, herbivorous mammals belonging to the family Tapiridae. They are similar in shape to a pig, with a short, prehensile nose trunk. Tapirs inhabit jungle and forest regions of South and Central America, with one species inh ...

and

rhinoceros A rhinoceros (; ; ), commonly abbreviated to rhino, is a member of any of the five extant species (or numerous extinct species) of odd-toed ungulates in the family Rhinocerotidae. (It can also refer to a member of any of the extinct specie ...

. Unlike the chestnut, which in the same individual may be large on the forelegs and smaller or even absent on the hindlegs, according to Ridgeway, chapter 2 the ergot is of roughly equal size on all four legs. However, as stated above, it is often noted that the ergot can be absent on some or all legs.

References

{{reflist

External links

About.com: Parts of the horse: the ergot
Horse anatomy

Evolution

See also

References

External links