World Library  
Flag as Inappropriate
Email this Article

Bovid

Article Id: WHEBN0000241281
Reproduction Date:

Title: Bovid  
Author: World Heritage Encyclopedia
Language: English
Subject: Brown bear, Antelope, Zebu, Water buffalo, Himalayan tahr, Shofar, Impala, Chamois, Bighorn sheep, Taymyr Peninsula
Collection:
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Bovid

A bovid (family Bovidae) is any of almost 140 species of cloven-hoofed, ruminant mammals with characteristic unbranching horns covered in a permanent sheath of keratin in at least the males.

The family is widespread, being native to Asia, Africa, Europe and North America, and diverse: members include bison, African buffalo, water buffalo, antelopes, gazelles, sheep, goats, muskoxen, and domestic cattle.

Characteristics

The largest bovid, the gaur, weighs well over a ton and stands 2.2 m (7.2 ft) 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 ruminants, bovids have four-chambered stomachs, which allow 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 kangaroos, rabbits and termites) are able to use micro-organisms living in their guts to break down cellulose by fermentation.

Because of the size and weight of their complex digestive systems, many bovids have solid, stocky builds. However, the more gracile species tend to have more selective diets, and be browsers rather than grazers. Their upper canine teeth and incisors 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.[2] The dental formula for bovids is similar to that of other ruminants 0.0.2-3.33.1.3.3 or 0.0.2-3.34.0.3.3

All bovids have four toes 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.[3][4] Male horn development has been linked to sexual selection,[5][6] while the presence of horns in females is likely due to natural selection.[5][7] The horns of females are usually smaller than those of males, and are sometimes of a different shape. The horns of female bovids are thought to have evolved for defense against predators or to express territoriality, as nonterritorial females, which are able to use crypsis for predator defense, often do not have horns.[7]

Evolution

The bovid family is known through fossils from the early Miocene, around 20 million years ago. The earliest bovids, such as Eotragus, were small animals, somewhat similar to modern gazelles, 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 because many bovids became adapted to more open, grassland habitat.[8] About 78 genera are 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 land masses. When these continents were later rejoined, this barrier was removed, and both groups expanded into each other's territory.[9]

The largest number of modern bovids is found in Africa, while substantial but less diverse populations are in Asia and North America. Many bovid species that evolved in Asia possibly 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.

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 10 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[further explanation needed] consistently. The phylogenetic relationships of the other subfamilies are still unclear or unresolved.[10]

Classification

Family Bovidae

  • Subfamily Bovinae: cattle, buffaloes and spiral-horned antelopes, 27 species in 10 genera
  • Subfamily Cephalophinae: duikers, 21 species in two genera
  • Subfamily Hippotraginae: grazing antelopes, seven species in three genera
  • Subfamily Antilopinae: gazelles, dwarf antelopes and the saiga, 35 species in 13 genera
  • Subfamily Caprinae: goat-antelopes: sheep, goats, muskox, takin, etc., 33 species in 10 genera
  • Subfamily Reduncinae: reedbucks, lechwe, 9 species in two genera
  • Subfamily Aepycerotinae: impala, one species in one genus
  • Subfamily Peleinae: grey rhebok, one species in one genus
  • Subfamily Alcelaphinae: wildebeest, topi/tsessebe, 10 species in four genera
  • Subfamily Pantholopinae: Tibetan antelope, one species in one genus

References

External links

  •  
  •  
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 



Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.