Bovid
Encyclopedia
A bovid is any of almost 140 species of cloven-hoofed ruminant mammal
at least the males of which bear characteristic unbranching horns covered in a permanent sheath of keratin
.
The family is widespread, being native to Asia
, Africa
, Europe
and North America
, and diverse: members include bison
, African buffalo
, water buffalo
, antelope
s, gazelle
s, sheep, goat
s, muskoxen, and domestic cattle
.
, weighs well over a ton and stands 2.2 metres high at the shoulder; the smallest, the royal antelope
, weighs about 3 kg and stands no taller than a large domestic cat. Some are thick-set and muscular; others are lightly built, with small frames and long legs. Many species
congregate into large groups with complex social structures, but others are mostly solitary. Within their extensive range, they occupy a wide variety of habitat types, from desert
to tundra
and from thick tropical forest to high mountains.
Most members of the family are herbivorous, except most duikers, which are omnivorous. Like other ruminant
s, bovids have a four-chambered stomach which allows them to digest plant material, such as grass
, that cannot be used by many other animals. Such plant material includes much cellulose
, and no higher animal can digest this directly. However, ruminants (and some others like kangaroo
s, rabbit
s and termite
s) are able to use microorganisms living in their gut to break down cellulose by fermentation
.
Because of the size and weight of their complex digestive systems, many bovids have a solid, stocky build. However, the more gracile species tend to have more selective diets, and be browsers rather than grazers. Their upper canine teeth
and incisor
s are missing, and are replaced with a hard, horny pad, that the lower teeth grind against to cut grass or other foliage. The outer pair of teeth in the front of the lower jaw are either considered to be canines, or to be incisors, with the canines missing. The cheek
teeth are low-crowned and selenodont, and are separated from the forward teeth by a wide gap, or diastema
. The dental formula
for bovids is similar to that of other ruminants or
All bovids have four toe
s on each foot – they walk on the central two (the hooves
), while the outer two (the dew-claws) are much smaller and rarely if ever touch the ground. Apart from some domesticated forms
, the males in all species have horns
, and in many the females do, too. The size and shape of the horns vary greatly, but the basic structure is always a pair of simple bony protrusions without branches, often having a spiral, twisted or fluted form, each covered in a permanent sheath of keratin
. The unique horn structure is the only unambiguous morphological feature of bovids that distinguish them from other pecorans. Male horn development has been linked to sexual selection, while the presence of horns in females is likely due to natural selection. The horns of females are usually smaller than those of males, and are sometimes of a different shape. It is theorized that the horns of female bovids evolved for defense against predators or to express territoriality, as non-territorial females who are able to use crypsis
for predator defense often do not have horns.
s from the early Miocene
, around 20 million years ago. The earliest bovids, such as Eotragus
, were small animals, somewhat similar to modern gazelle
s, and probably lived in woodland
environments. The bovids rapidly diversified, and by the late Miocene, the number of bovid species had greatly expanded. This late Miocene radiation was partly due to the fact that many bovids became adapted to more open, grassland habitat. There are 78 genera known from the Miocene (compared to 50 today).
Early in their evolutionary history, the bovids split into two main clades: Boodontia and Aegodontia. This early split between Boodontia (of Eurasian origin) and Aegodontia (of African origin) has been attributed to the continental divide between these landmasses. When these continents were later rejoined, this barrier was removed, and both groups expanded into each other's territory.
The largest number of modern bovids is found in Africa
, while substantial but less diverse populations are in Asia
and North America
. Some scientists has suggested that many bovid species that evolved in Asia could not survive predation by humans arriving from Africa in the late Pleistocene
. By contrast, African species had many thousands or a few million years to adapt to the gradual development of human hunting skills. Yet many of the commonly domesticated bovid species (goats, sheep, water buffalo and yak
) originated in Asia. This may be because Asian bovids had less fear of humans and were more docile.
The small number of modern American bovids are relatively recent arrivals over the Bering land bridge
, but they long predate human arrival.
Among the eight to ten subfamilies presented here, only some groups have a well-established phylogeny
. The Bovinae, for example, are monophyletic
and basal
; while the Caprinae, Hippotraginae, and Alcelaphinae cluster together consistently. The phylogenetic relationships of the other subfamilies are still unclear or unresolved.
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
at least the males of which bear characteristic unbranching horns covered in a permanent sheath of keratin
Keratin
Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...
.
The family is widespread, being native to Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, and diverse: members include bison
Bison
Members of the genus Bison are large, even-toed ungulates within the subfamily Bovinae. Two extant and four extinct species are recognized...
, African buffalo
African Buffalo
The African buffalo, affalo, nyati, Mbogo or Cape buffalo is a large African bovine. It is not closely related to the slightly larger wild Asian water buffalo, but its ancestry remains unclear...
, water buffalo
Water buffalo
The water buffalo is a domesticated bovid widely kept in Asia, Europe and South America.Water buffalo can also refer to:*Wild water buffalo , the wild ancestor of the domestic water buffalo...
, antelope
Antelope
Antelope is a term referring to many even-toed ungulate species indigenous to various regions in Africa and Eurasia. Antelopes comprise a miscellaneous group within the family Bovidae, encompassing those old-world species that are neither cattle, sheep, buffalo, bison, nor goats...
s, gazelle
Gazelle
A gazelle is any of many antelope species in the genus Gazella, or formerly considered to belong to it. Six species are included in two genera, Eudorcas and Nanger, which were formerly considered subgenera...
s, sheep, goat
Goat
The domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s, muskoxen, and domestic cattle
Cattle
Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...
.
Characteristics
The largest bovid, the gaurGaur
The gaur , also called Indian bison, is a large bovine native to South Asia and Southeast Asia. The species is listed as vulnerable on the IUCN Red List since 1986 as the population decline in parts of the species' range is likely to be well over 70% over the last three generations...
, weighs well over a ton and stands 2.2 metres high at the shoulder; the smallest, the royal antelope
Royal Antelope
The Royal Antelope is a West African antelope, only 25–30 cm high at the shoulder and weighing only 3.2–3.6 kg — it is the smallest of all antelopes. Their calves are small enough to fit into the average person's open hand...
, weighs about 3 kg and stands no taller than a large domestic cat. Some are thick-set and muscular; others are lightly built, with small frames and long legs. Many species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
congregate into large groups with complex social structures, but others are mostly solitary. Within their extensive range, they occupy a wide variety of habitat types, from desert
Desert
A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...
to tundra
Tundra
In physical geography, tundra is a biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian тундра from the Kildin Sami word tūndâr "uplands," "treeless mountain tract." There are three types of tundra: Arctic tundra, alpine...
and from thick tropical forest to high mountains.
Most members of the family are herbivorous, except most duikers, which are omnivorous. Like other ruminant
Ruminant
A ruminant is a mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first compartment of the stomach, principally through bacterial actions, then regurgitating the semi-digested mass, now known as cud, and chewing it again...
s, bovids have a four-chambered stomach which allows them to digest plant material, such as grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...
, that cannot be used by many other animals. Such plant material includes much cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
, and no higher animal can digest this directly. However, ruminants (and some others like kangaroo
Kangaroo
A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...
s, rabbit
Rabbit
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
s and termite
Termite
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera , but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea...
s) are able to use microorganisms living in their gut to break down cellulose by fermentation
Fermentation (biochemistry)
Fermentation is the process of extracting energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. In contrast, respiration is where electrons are donated to an exogenous electron acceptor, such as oxygen,...
.
Because of the size and weight of their complex digestive systems, many bovids have a solid, stocky build. However, the more gracile species tend to have more selective diets, and be browsers rather than grazers. Their upper canine teeth
Canine tooth
In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed teeth...
and incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
s are missing, and are replaced with a hard, horny pad, that the lower teeth grind against to cut grass or other foliage. The outer pair of teeth in the front of the lower jaw are either considered to be canines, or to be incisors, with the canines missing. The cheek
Cheek
Cheeks constitute the area of the face below the eyes and between the nose and the left or right ear. They may also be referred to as jowls. "Buccal" means relating to the cheek. In humans, the region is innervated by the buccal nerve...
teeth are low-crowned and selenodont, and are separated from the forward teeth by a wide gap, or diastema
Diastema (dentistry)
Diastema is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars.-In humans:...
. The dental formula
Dentition
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, the characteristic arrangement, kind, and number of teeth in a given species at a given age...
for bovids is similar to that of other ruminants or
All bovids have four toe
Toe
Toes are the digits of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being digitigrade. Humans, and other animals that walk on the soles of their feet, are described as being plantigrade; unguligrade animals are those that walk on hooves at the tips of...
s on each foot – they walk on the central two (the hooves
Hoof
A hoof , plural hooves or hoofs , is the tip of a toe of an ungulate mammal, strengthened by a thick horny covering. The hoof consists of a hard or rubbery sole, and a hard wall formed by a thick nail rolled around the tip of the toe. The weight of the animal is normally borne by both the sole...
), while the outer two (the dew-claws) are much smaller and rarely if ever touch the ground. Apart from some domesticated forms
Polled livestock
Polled livestock are livestock without horns, of species that normally have them. The term refers both to breeds or strains which are naturally polled through selective breeding and also to naturally horned animals which have been dehorned...
, the males in all species have horns
Horn (anatomy)
A horn is a pointed projection of the skin on the head of various animals, consisting of a covering of horn surrounding a core of living bone. True horns are found mainly among the ruminant artiodactyls, in the families Antilocapridae and Bovidae...
, and in many the females do, too. The size and shape of the horns vary greatly, but the basic structure is always a pair of simple bony protrusions without branches, often having a spiral, twisted or fluted form, each covered in a permanent sheath of keratin
Keratin
Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...
. The unique horn structure is the only unambiguous morphological feature of bovids that distinguish them from other pecorans. Male horn development has been linked to sexual selection, while the presence of horns in females is likely due to natural selection. The horns of females are usually smaller than those of males, and are sometimes of a different shape. It is theorized that the horns of female bovids evolved for defense against predators or to express territoriality, as non-territorial females who are able to use crypsis
Crypsis
In ecology, crypsis is the ability of an organism to avoid observation or detection by other organisms. It may be either a predation strategy or an antipredator adaptation, and methods include camouflage, nocturnality, subterranean lifestyle, transparency, and mimicry...
for predator defense often do not have horns.
Evolution
The bovid family is known through fossilFossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s from the early Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
, around 20 million years ago. The earliest bovids, such as Eotragus
Eotragus
Eotragus is an early bovid from Europe, Africa, and Asia during the Miocene some 20-18 million years ago. It is related to the modern Nilgai and Four-horned Antelope. It was small and probably lived in woodland environments.-External links:**...
, were small animals, somewhat similar to modern gazelle
Gazelle
A gazelle is any of many antelope species in the genus Gazella, or formerly considered to belong to it. Six species are included in two genera, Eudorcas and Nanger, which were formerly considered subgenera...
s, and probably lived in woodland
Woodland
Ecologically, a woodland is a low-density forest forming open habitats with plenty of sunlight and limited shade. Woodlands may support an understory of shrubs and herbaceous plants including grasses. Woodland may form a transition to shrubland under drier conditions or during early stages of...
environments. The bovids rapidly diversified, and by the late Miocene, the number of bovid species had greatly expanded. This late Miocene radiation was partly due to the fact that many bovids became adapted to more open, grassland habitat. There are 78 genera known from the Miocene (compared to 50 today).
Early in their evolutionary history, the bovids split into two main clades: Boodontia and Aegodontia. This early split between Boodontia (of Eurasian origin) and Aegodontia (of African origin) has been attributed to the continental divide between these landmasses. When these continents were later rejoined, this barrier was removed, and both groups expanded into each other's territory.
The largest number of modern bovids is found in Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, while substantial but less diverse populations are in Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. Some scientists has suggested that many bovid species that evolved in Asia could not survive predation by humans arriving from Africa in the late Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
. By contrast, African species had many thousands or a few million years to adapt to the gradual development of human hunting skills. Yet many of the commonly domesticated bovid species (goats, sheep, water buffalo and yak
Yak
The yak, Bos grunniens or Bos mutus, is a long-haired bovine found throughout the Himalayan region of south Central Asia, the Tibetan Plateau and as far north as Mongolia and Russia. In addition to a large domestic population, there is a small, vulnerable wild yak population...
) originated in Asia. This may be because Asian bovids had less fear of humans and were more docile.
The small number of modern American bovids are relatively recent arrivals over the Bering land bridge
Bering land bridge
The Bering land bridge was a land bridge roughly 1,000 miles wide at its greatest extent, which joined present-day Alaska and eastern Siberia at various times during the Pleistocene ice ages. Like most of Siberia and all of Manchuria, Beringia was not glaciated because snowfall was extremely light...
, but they long predate human arrival.
Taxonomy
The bovid family is commonly subdivided into eight subfamilies. Recently, two additional subfamilies have been recognised. The eight traditional subfamilies can be divided into two clades, the Boodontia (with the Bovinae as sole members) and the Aegodontia (composed of all other subfamilies). Some authors do not agree with the high number of subfamilies, although they do recognise these two clades. However, these are treated as subfamilies instead: Bovinae (without change) and Antilopinae (with all of the Aegodontid subfamilies as tribes within it).Among the eight to ten subfamilies presented here, only some groups have a well-established phylogeny
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
. The Bovinae, for example, are monophyletic
Monophyly
In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...
and basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
; while the Caprinae, Hippotraginae, and Alcelaphinae cluster together consistently. The phylogenetic relationships of the other subfamilies are still unclear or unresolved.
Classification
Family Bovidae- Subfamily BovinaeBovinaeThe biological subfamily Bovinae includes a diverse group of 10 genera of medium to large sized ungulates, including domestic cattle, the bison, African buffalo, the water buffalo, the yak, and the four-horned and spiral-horned antelopes...
: cattle, buffaloes and spiral-horned antelopes, 27 species in 10 genera - Subfamily Cephalophinae: duikers, 21 species in 2 genera
- Subfamily Hippotraginae: grazing antelopes, 7 species in 3 genera
- Subfamily AntilopinaeAntilopinaeAntilopinae is a subfamily of Bovidae. The gazelles, blackbucks, springboks, gerenuks, dibatags and Central Asian gazelles are often referred to as "True Antelopes" and are usually the sole representatives of the Antilopinae...
: gazelles, dwarf antelopes and the saiga, 34 species in 13 genera - Subfamily Caprinae: goat-antelopes: sheep, goats, muskox, takin etc., 33 species in 10 genera
- Subfamily ReduncinaeReduncinaeThe subfamily Reduncinae is composed 8 species of antelope all of which dwell in marshes, floodplains or other well-watered areas, including the waterbucks and reedbucks...
: reedbucks, lechwe, 9 species in 2 genera - Subfamily AepycerotinaeImpalaAn impala is a medium-sized African antelope. The name impala comes from the Zulu language meaning "gazelle"...
: impala, 1 species in 1 genus - Subfamily PeleinaeGrey RhebokThe Grey Rhebok or Grey Rhebuck is a species of antelope endemic to South Africa, Zimbabwe, Lesotho and Swaziland....
: rhebok, 1 species in 1 genus - Subfamily AlcelaphinaeAlcelaphinaeThe subfamily Alcelaphinae contains Wildebeest, Hartebeest, Bonteboks and several similar species. All in all it contains 10 species in 4 genera, although Beatragus is sometimes considered a subgenus of Damaliscus, and Sigmoceros for the Lichtenstein's Hartebeest.* Family Bovidae** Subfamily...
: wildebeestWildebeestThe wildebeest , also called the gnu is an antelope of the genus Connochaetes. It is a hooved mammal...
, topi/tsessebe, 10 species in 4 genera - Subfamily Pantholopinae: Chiru