Bovids display the characteristic long limbs and unique foot and unguligrade stance of artiodactyls. They are paraxonic, as the line of symmetry of the foot runs between the third and fourth digits. In most bovids, the lateral digits are either reduced or absent and the animal's weight is born on the remaining central digits. The third and forth metapodials are completely fused in bovids, resulting the cannon bone. The joint between the cannon bone and proximal phalanges includes four sesamoid bones that act as joint stops. The ulna and fibula is reduced and fused with the radius and tibia respectively. This arrangement provides for a wide angle of flexion and extension, but restricts lateral movement.
As a members of the suborder Ruminantia, bovids possess the trademark multi-chambered fore-gut adapted for cellulolytic fermentation and digestion. Thus, they are obligate herbivores, which is also reflected by their hypsodont and selenodont tooth morphology. Their upper incisors are absent and their upper canines are either reduced or absent. Instead of upper incisors, bovids have an area of tough, thickened tissue known as the dental pad, which provides a surface for gripping plant materials. The lower incisors project forward and are joined by modified canines that emulate the incisors. Their modified incisors are followed by a long toothless gap known as a diastema. Bovids have a generalized dental formula of I 0/3, C 0/1, P 2-3/3, M 3/3.
The distinguishing characteristic of the Bovidae family is their unbranching horns. The horns originate from a bony core known as the the cornual process (os cornu) of the frontal bone and are covered in a thick keratinized sheath. Horns are not shed like the antlers of cervids and most grow continuously. Except for Indian four-horned antelopes, horns occur in pairs and in a fascinating array of unique forms from curved daggers in mountain goat to the thick, rippled coils of greater kudu.
Bovids exhibit a wide range of sizes and pelage coloration and patterns. For example, gaurs have a maximum shoulder height of 3.3 m (10.82 ft) and a maximum weight of more than 1000 kg (2200 lbs), and pygmy antelope have a maximum shoulder height of 300 mm (1 ft) and a maximum weight of 3 kg (6.6 lbs). Forest and bush species tend to have shorter limbs and more developed hindquarters and cryptic pelage that helps them blend into their surroundings. Open habitat species have long, forelimbs that increase stride length and occasionally bold color patterns or stripes. These adaptations help bovids evade potential predators through the various mechanisms of hiding (cryptic coloration), escaping (increased stride length), or confusion (striped pelage).
Most bovids are sexually dimorphic. Males always have horns, which are used in ritualized fighting during the mating season. The horns of males tend to be more complex in design and more robust than those of females, which tend to be straighter, thinner, and simpler in design. Horns are present in females in approximately 75% of genera over 40 kg in mass and are usually absent in those less than 25 kg. This could be the result of differing life history strategies or the physiological cost of growing horns. Larger species are more likely to defend themselves against potential predators, and smaller species tend to retreat when threatened. In addition to sexual dimorphism in morphological characteristics, males also have better developed scent-glands than females, which are reduced or absent in species from the subfamily Bovinae.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike; female larger; male larger; sexes shaped differently; ornamentation
- Fowler, M., R. Miller. 2003. Zoo and Wild Animal Medicine. St. Louis: Saunders.