Difference between revisions of "Ungulate" - New World Encyclopedia

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'''Ungulates''', or hoofed [[mammal]]s, are members of the orders Perissodactyla and Artiodactyla. Ungulates include most of the large land mammals on earth. They are found naturally on all continents except Antarctica and Australia (where they were introduced by humans) and in almost all environments from forests to grasslands to deserts to high mountains to the tundra.  They range in size from the Lesser Malay mouse deer (''Tragulus javanicus'') which weighs 1.5 to 2.5 kg (3.3 to 5.5 lbs) to the White rhinoceros (''Ceratotherium simum'') and the Hippopotamus (''Hippopotamus amphibius'') which can weigh over 3,200 kg (7,000 lbs) (Huffman 2006).
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{{Copyedited}}{{Paid}}{{Approved}}{{Images OK}}{{Submitted}}
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'''Ungulates,''' or hoofed [[mammal]]s, are members of the orders [[#Perissodactyla: Odd-toed ungulates|Perissodactyla]] (odd-toed ungulates) and [[#Artiodactyla: Even-toed ungulates|Artiodactyla]] (even-toed ungulates). Ungulates include most of the large land mammals on earth.  
  
Ungulates are tremendously important to humans. From earliest times they have been widely hunted for food. Some species have played important roles as domesticated animals; including [[sheep]] (''Ovis aries''), [[goat]]s (''Capra hircus''), [[pig]]s (''Sus scrofa''), [[cattle]] (''Bos taurus''), [[buffalo]]s (''Bubalus bubalus''), [[horse]]s (''Equus caballus''), [[donkey]]s (''Equus asinus''), camels (''Camelus dromedarius'' and ''C. bactrianus''), llamas (''Lama guanicoe''), and reindeer (''Rangifer tarandus'').
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Ungulates are found naturally on all continents except [[Antarctica]] and [[Australia]] (where they were introduced by [[human]]s) and in almost all land environments from forests to grasslands to deserts to high mountains to the [[tundra]]. They range in size from the Lesser Malay mouse deer (''Tragulus javanicus'') which weighs 1.5 to 2.5 kg (3.3 to 5.5 lbs) to the white [[rhinoceros]] (''Ceratotherium simum'') and the [[hippopotamus]] (''Hippopotamus amphibius'') which can weigh over 3,200 kg (7,000 lbs) (Huffman 2006).
[[Image:Giraffe standing.jpg|thumb|Giraffe]]
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[[Image:White-tailed deer.jpg|thumb|right|White-tailed deer]]
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Ungulates are tremendously important to humans. From earliest times they have been widely hunted for food. Some [[species]] have played important roles as domesticated animals, providing food, fiber, transportation, and many other benefits. Important domestic ungulates include [[sheep]] (''Ovis aries''), [[goat]]s (''Capra hircus''), [[pig]]s (''Sus scrofa''), [[cattle]] (''Bos taurus''), [[buffalo]]s (''Bubalus bubalus''), [[horse]]s (''Equus caballus''), [[donkey]]s (''Equus asinus''), [[camel]]s (''Camelus dromedarius'' and ''C. bactrianus''), [[llama]]s (''Lama guanicoe''), and [[reindeer]] (''Rangifer tarandus'').
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[[Image:Giraffe standing.jpg|thumb|Giraffe, ''Giraffa camelopardalis'']]
Other orders of animals which are not ungulates but are closely related are:
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[[Image:White-tailed deer.jpg|thumb|right|White-tailed deer, ''Odocoileus virginianus'']]  
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Many of the even-toed ungulates have developed a [[symbiosis|symbiotic]] relationship with microorganisms. Through this mutually beneficial relationship, the mammals are able to digest [[cellulose]] into a form of [[carbohydrate]] they can use, as well as other digestive benefits, while the microorganisms receive food and shelter.
 +
 
 +
Other orders of animals that are closely related to ungulates are:
  
*Tubulidentata - Aardvark
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*'''Tubulidentata''' – [[Aardvark]]
*Hyracoidea - Hyraxes
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*'''Hyracoidea''' – [[Hyrax]]es
*Proboscidea - [[Elephant]]s
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*'''Proboscidea''' - [[Elephant]]s
*Sirenia - Sea cows
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*'''Sirenia''' – [[Sea cow]]s
*Cetacea - [[Whale]]s and Dolphins
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*'''Cetacea''' - [[Whale]]s and [[dolphin]]s
  
 
==Ungulate features==
 
==Ungulate features==
  
The word "ungulate" comes from the Latin word ''ungula'' meaning "hoof"A hoof is a claw or nail which protects the toe and enables it to support the weight of the animal. Ungulates stand and run on the tips of their toes. Most of the weight is supported by the hoofs, with the result that the form of locomotion of ungulates is described as "unguligrade" (rather than "digitigrade", where the toes touch the ground, or "plantigrade", where the entire foot is on the ground, as in humans) (Huffman 2006). This plus modifications in the bones of the legs lengthen the legs which provides for faster running. It is thought that the ungulates evolved on grasslands where the ability to run quickly is of vital importance in escaping preditors (UCMP 2006).
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The word "ungulate" comes from the Latin word ''ungula,'' meaning "hoof." A hoof is a claw or nail that protects the toe and enables it to support the weight of the animal. Ungulates stand and run on the tips of their toes. Most of the weight is supported by the hoofs, with the result that the form of locomotion of ungulates is described as "unguligrade" (rather than "digitigrade," where the toes touch the ground, or "plantigrade," where the entire foot is on the ground, as in humans) (Huffman 2006). This plus modifications in the bones of the legs lengthen the legs, which provides for faster running. It is thought that the ungulates evolved on [[grassland]]s where the ability to run quickly is of vital importance in escaping predators (UCMP 2006).
  
Most ungulates are herbivores, eating [[plant]]s. Some are grazers, eating [[grass]], and some are browsers, eating leaves of [[tree]]s and other plants. Many ungulates have large, complexly grooved molar teeth to grind their food. The canine teeth are most often reduced.   A few ungulates, such as the [[pig]]s, are omnivores, eating a variety of foods including meat.
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Most ungulates are herbivores, eating [[plant]]s. Some are grazers, eating [[grass]], and some are browsers, eating leaves of [[tree]]s and other plants. Many ungulates have large, complexly grooved molar teeth to grind their food. In most, the canine teeth are reduced. A few ungulates, such as the [[pig]]s, are omnivores, eating both plant and animal foods.
  
==Perissodactyla: odd-toed ungulates==
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==Perissodactyla: Odd-toed ungulates==
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{{main|Odd-toed ungulate}}
 
{{Taxobox_begin | color = pink | name = Odd-toed ungulates}}
 
{{Taxobox_begin | color = pink | name = Odd-toed ungulates}}
{{Taxobox_image | image = [[Image:00296 zebra.jpg|240px]] | caption = [[Plains Zebra]]s}}
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{{Taxobox_image | image = [[Image:00296 zebra.jpg|240px]] | caption = Plains Zebras, ''Equus quagga''}}
 
{{Taxobox_begin_placement | color = pink}}
 
{{Taxobox_begin_placement | color = pink}}
 
{{Taxobox_regnum_entry | taxon = [[Animal]]ia}}
 
{{Taxobox_regnum_entry | taxon = [[Animal]]ia}}
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{{Taxobox_end}}
 
{{Taxobox_end}}
  
In the Perissodactyla, the odd-toed ungulates, the central axis of the foot passes through the third toe. In rhinoceroses the first and fifth toes are lost and the animal walks on the remaining three toes. In horses only the third toe remains and supports the whole weight of the animal. Tapirs have four toes on their front feet and three on their hind feet.
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In the Perissodactyla, the odd-toed ungulates, the central axis of the foot passes through the third toe. In [[rhinoceros]]es, the first and fifth toes are lost and the animal walks on the remaining three toes. In [[horse]]s, only the third toe remains and supports the whole weight of the animal. [[Tapir]]s have four toes on their front feet and three on their hind feet.  
  
 
===Evolution===
 
===Evolution===
The odd-toed ungulates arose in what is now [[North America]] in the late [[Paleocene]], less than 10 million years after the [[dinosaur]]s died out. By the start of the [[Eocene]] (55 million years ago) they had diversified and spread out to occupy several continents. The horses and tapirs both evolved in North America; the rhinoceroses appear to have developed in [[Asia]] from tapir-like animals and then spread to the Americas during the middle Eocene (about 45 million years ago). There were 12 families, of which only three survive. These families were very diverse in form and size; they included the enormous Brontotheres and the bizarre Chalicotheres. The largest perissodactyl, an Asian rhinoceros called Paraceratherium, reached 11,000 kg (12 tons), more than twice the weight of an elephant.
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The odd-toed ungulates arose in what is now [[North America]] in the late [[Paleocene]], less than 10 million years after the [[dinosaur]]s died out. By the start of the [[Eocene]] (55 million years ago), they had diversified and spread out to occupy several continents. The [[horse]]s and [[tapir]]s both evolved in North America; the [[rhinoceros]]es appear to have developed in [[Asia]] from tapir-like animals and then spread to the Americas during the middle Eocene (about 45 million years ago).  
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[[Image:Central American Tapir-Belize20.jpg|thumb|left|Baird's tapir, ''Tapirus bairdii'']]
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There were 12 families categorized from the [[fossil]] record, of which only three survive. These families were very diverse in form and size; they included the enormous Brontotheres and the bizarre Chalicotheres. The largest perissodactyl, an Asian rhinoceros called Paraceratherium, reached 11,000 kg (12 tons), more than twice the weight of an [[elephant]].
  
Perissodactyls were the dominant group of large terrestrial browsers right through the [[Oligocene]]. However, the rise of grasses in the [[Miocene]] (about 20 million years ago) saw a major change: the [[even-toed ungulate]]s with their more complex stomachs were better able to adapt to a coarse, low-nutrition diet, and soon rose to prominence. Nevertheless, many odd-toed species survived and prospered until the late [[Pleistocene]] (about 10,000 years ago) when they faced the pressure of human hunting and habitat change.  
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Perissodactyls were the dominant group of large terrestrial browsers right through the [[Oligocene]]. However, the rise of grasses in the [[Miocene]] (about 20 million years ago) saw a major change: the [[even-toed ungulate]]s with their more complex stomachs were better adapted to a coarse, low-nutrition diet, and soon rose to prominence. Nevertheless, many odd-toed species survived and prospered until the late [[Pleistocene]] (about 10,000 years ago) when they faced the pressure of human hunting and habitat change.  
  
Today there are only 17 species of odd-toed ungulates still living and all of them are in danger of extinction except for the [[horse]] and the [[donkey]], which have been domesticated. (UCMP 2006).
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Today, there are only 19 species of odd-toed ungulates still living and all of them are in danger of [[extinction]] except for the [[horse]] and the [[donkey]], which have been domesticated (UCMP 2006).
  
 
===Perissodactyla families===
 
===Perissodactyla families===
  
*Tapiridae - Tapirs. Central and South America. 4 species
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*Tapiridae – [[Tapir]]s. Southeast Asia, Central and South America. 4 species
*Rhinocerotidae - Rhinoceroses. Africa and southern Asia. 5 species
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*Rhinocerotidae – [[Rhinoceros]]es. Africa and southern Asia. 5 species
*Equidae - Horses. Africa, Europe, and Asia. 8 species.
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*[[Equidae]] – [[Horse]] family (horses, [[donkey]], [[zebra]]s, [[onager]]). Africa, Europe, and Asia. 9 or 10 species.
  
 
==Artiodactyla: Even-toed ungulates==
 
==Artiodactyla: Even-toed ungulates==
 
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{{main|Even-toed ungulate}}
 
{{Taxobox_begin | color = pink | name = Even-toed ungulates}}
 
{{Taxobox_begin | color = pink | name = Even-toed ungulates}}
{{Taxobox_image | image = [[image:Mountain-Goat-225.jpg|240px]] | caption = [[Rocky Mountain Goat]], ''Oreamnos americanus''}}
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{{Taxobox_image | image =}}
 
{{Taxobox_begin_placement | color = pink}}
 
{{Taxobox_begin_placement | color = pink}}
 
{{Taxobox_regnum_entry | taxon = [[Animal]]ia}}
 
{{Taxobox_regnum_entry | taxon = [[Animal]]ia}}
Line 58: Line 65:
  
  
In Artiodactyla, even-toed ungulates, the axis of the leg passes between the third and forth toes. The weight of the most even-toed ungluates is born evenly on the third and fourth toe of each foot with the other toes being absent, or vestigial in the case of most deer. Hippopotamuses and pigs have four functional toes on each foot (Nowak 1983).
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In Artiodactyla, even-toed ungulates, the axis of the leg passes between the third and fourth toes. The weight of most even-toed ungulates is born evenly on the third and fourth toe of each foot with the other toes being absent, or vestigial in the case of most [[deer]]. [[Hippopotamus]]es and [[pig]]s have four functional toes on each foot (Nowak 1983).
  
Except for Hippopotamuses, peccaries, and pigs all even-toed ungulates digest their food by the process of rumination. Their stomachs are divided into chambers, three for camels and mouse deer and four for the other families (Nowak 1983). After food is swallowed it is kept in the first chamber for a while where it is partly digested with the help of micro-organisms, [[bacteria]] and [[protist]]s . In this [[symbiosis|symbiotic]] relationship the micro-organisms break down the cellulose in the plant material eaten into carbohydrates which the ungulate can digest. Both sides benefit from this relationship. The micro-organisms get food and a place to live and the ungulate gets help with its digestion. The micro-organisms themselves are also digested providing proteins and other nutrients, but not before they have a chance to reproduce and give rise to a new generation so the relationship can continue (Lott 2003). The process also generates heat which can help to keep the ungulate warm and breaks down plant toxins which permits plants which are poisonous to other animals to be eaten (Voelker 1986).
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Except for hippopotamuses, peccaries, and pigs, all even-toed ungulates digest their food by the process of rumination. Their stomachs are divided into chambers, three for [[camel]]s and [[mouse deer]] and four for the other families (Nowak 1983). After food is swallowed, it is kept in the first chamber for a while where it is partly digested with the help of [[microorganism]]s, [[bacteria]], and [[protist]]s. In this [[symbiosis|symbiotic]] relationship, the microorganisms break down the [[cellulose]] in the [[plant]] material into [[carbohydrate]]s, which the ungulate can digest. Both sides receive some benefit from this relationship. The microorganisms get food and a place to live and the ungulate gets help with its digestion. The partly digested food is then sent back up to the mouth where it is chewed again and sent on to the other parts of the stomach to be completely digested. The microorganisms themselves are also digested, providing [[protein]]s and other nutrients, but not before the community of microorganisms has had a chance to reproduce and give rise to a new generation so the relationship can continue (Lott 2003). The process also generates heat, which can help to keep the ungulate warm, and breaks down plant toxins, which permits [[plant]]s that are poisonous to other animals to be eaten (Voelker 1986).
 +
 
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Many even-toed ungulates have horns or antlers.
 
   
 
   
 
===Evolution===
 
===Evolution===
As with many mammal groups, even-toed ungulates first appeared during the Early [[Eocene]] (about 54 million years ago). In form they were rather like today's chevrotains: small, short-legged creatures that ate leaves and the soft parts of plants. By the Late Eocene (46 million years ago), the three modern suborders had already developed: Suina (the [[pig]] group); Tylopoda (the [[camel]] group); and Ruminantia (the [[antelope]] group). Nevertheless, artiodactyls were far from dominant at that time: the odd-toed ungulates were much more successful and far more numerous. Even-toed ungulates survived in niche roles, usually occupying marginal habitats, and it is presumably at that time that they developed their complex digestive systems, which allowed them to survive on lower-grade feed.
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As with many [[mammal]] groups, even-toed ungulates first appeared during the Early [[Eocene]] (about 54 million years ago). In form, they were rather like today's chevrotains: small, short-legged creatures that ate [[leaf|leaves]] and the soft parts of [[plant]]s. By the Late Eocene (46 million years ago), the three modern suborders had already developed: Suina (the [[pig]] group); Tylopoda (the [[camel]] group); and Ruminantia (the [[antelope]] group). Nevertheless, artiodactyls were far from dominant at that time: the odd-toed ungulates were much more successful and far more numerous. Even-toed ungulates survived in niche roles, usually occupying marginal habitats, aided by their complex digestive systems, which allowed them to survive on lower-grade feed.  
 
 
The appearance of [[grass]]es during the Eocene and their subsequent spread during the [[Miocene]] (about 20 million years ago) saw a major change: grasses are very difficult to digest and the even-toed ungulates with their highly-developed [[stomach]]s were better able to adapt to this coarse, low-nutrition diet, and soon replaced the odd-toed ungulates as the dominant terrestrial herbivores.
 
  
 +
The appearance of [[grass]]es during the Eocene and their subsequent spread during the [[Miocene]] (about 20 million years ago) saw a major change: grasses are very difficult to digest and the even-toed ungulates with their highly-developed [[stomach]]s were better able to adapt to this coarse, low-nutrition diet. They gradually replaced the odd-toed ungulates as the dominant terrestrial herbivores.
  
There are 192 species of even-toed ungulates living today.
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There are over 200 [[species]] of even-toed ungulates living today. Some are [[endangered species|endangered]] due to hunting and loss of habitat. On the other hand, many species are doing well and some have expanded their ranges due to being introduced to new locations by [[human]]s.
 +
[[Image:African Buffalo.JPG|thumb|240px|African buffalo, ''Syncerus caffer'']]
  
 
===Artiodactyla families===
 
===Artiodactyla families===
  
*Suina - Pigs. Africa, Asia, and Europe. 8 species.
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*Suidae – [[Pig]]s. Africa, Asia, and Europe.  
*Tayassuidae - Peccaries. North and South America. 3 species.
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*Tayassuidae – [[Peccary|Peccaries]]. North and South America.  
*Hippopotamidae - Hippopotamuses. Africa. 2 species.
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*Hippopotamidae – [[Hippopotamus]]es. Africa.  
*Camelidae - Camels, llamas. Africa, Asia, and South America. 6 species.
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*Camelidae – [[Camel]]s, [[llama]]s. Africa, Asia, and South America.  
*Tragulidae - Mouse deer. Africa and Asia. 4 species.
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*Tragulidae – [[Mouse deer]] or chevrotains. Africa and Asia.  
*Cervidae - Deer, elk, moose. North and South America, Europe, Asia, northern Africa. 38 species.
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*Cervidae – [[Deer]], [[elk]], [[moose]]. North and South America, Europe, Asia, northern Africa.  
*Giraffidae - Giraffe and okapi. Africa. 2 species.
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*Moschidae – [[Musk deer]]. Asia.
*Antilocapridae - Pronghorn. North America. 1 species.
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*Giraffidae – [[Giraffe]] and [[okapi]]. Africa.  
*Bovidae - Antelopes, cattle, goats, and sheep. Africa, Europe, Asia, and North America. 128 species.
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*Antilocapridae – [[Pronghorn]]. North America.  
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*[[Bovid|Bovidae]] – [[Antelope]], [[buffalo]], [[cattle]], [[goat]]s, and [[sheep]]. Africa, Europe, Asia, and North America.
  
 
==References==
 
==References==
*Huffman, B. 2006 ''The Ultimate Ungulate Page'' Website [http://www.ultimateungulate.com]
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*Huffman, B. 2007. [http://www.ultimateungulate.com The Ultimate Ungulate Page.] Retrieved April 2, 2007.
*Lott, D.F. 2002. ''American Bison''. Berkeley, California, USA : University of California Press
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*Lott, D. F. 2002. ''American Bison.'' Berkeley: University of California Press
*Nowak, R.M. and Paradiso, J.L. 1983. ''Walker's Mammals of the World''. Baltimore, Maryland, USA : The Johns Hopkins University Press
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*Nowak, R. M., and J. L. Paradiso. 1983. ''Walker's Mammals of the World.'' Baltimore: Johns Hopkins University Press.
*University of California Museum of Paleontology (UCMP) 2006. "Ungulates: Hoofed Mammals"[http://www.ucmp.berkeley.edu/mammal/eutheria/ungulate.html]
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*University of California Museum of Paleontology (UCMP). 2006. [http://www.ucmp.berkeley.edu/mammal/eutheria/ungulate.html Ungulates: Hoofed Mammals.] Retrieved April 2, 2007.
*Voelker, W. 1986. ''The Natural History of Living Mammals''. Medford, New Jersey, USA : Plexus Publishing, Inc.
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*Voelker, W. 1986. ''The Natural History of Living Mammals.'' Medford, NJ: Plexus Publishing.
  
 
{{credit3|Ungulate|81423561|Even-toed_ungulate|80842177|Odd-toed_ungulate|76905771}}
 
{{credit3|Ungulate|81423561|Even-toed_ungulate|80842177|Odd-toed_ungulate|76905771}}
 
[[Category:Life sciences]]
 
[[Category:Life sciences]]
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[[Category:Animals]]
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[[Category:Mammals]]
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[[Category:Ungulates]]

Latest revision as of 23:30, 11 November 2022

Ungulates, or hoofed mammals, are members of the orders Perissodactyla (odd-toed ungulates) and Artiodactyla (even-toed ungulates). Ungulates include most of the large land mammals on earth.

Ungulates are found naturally on all continents except Antarctica and Australia (where they were introduced by humans) and in almost all land environments from forests to grasslands to deserts to high mountains to the tundra. They range in size from the Lesser Malay mouse deer (Tragulus javanicus) which weighs 1.5 to 2.5 kg (3.3 to 5.5 lbs) to the white rhinoceros (Ceratotherium simum) and the hippopotamus (Hippopotamus amphibius) which can weigh over 3,200 kg (7,000 lbs) (Huffman 2006).

Ungulates are tremendously important to humans. From earliest times they have been widely hunted for food. Some species have played important roles as domesticated animals, providing food, fiber, transportation, and many other benefits. Important domestic ungulates include sheep (Ovis aries), goats (Capra hircus), pigs (Sus scrofa), cattle (Bos taurus), buffalos (Bubalus bubalus), horses (Equus caballus), donkeys (Equus asinus), camels (Camelus dromedarius and C. bactrianus), llamas (Lama guanicoe), and reindeer (Rangifer tarandus).

Giraffe, Giraffa camelopardalis
White-tailed deer, Odocoileus virginianus

Many of the even-toed ungulates have developed a symbiotic relationship with microorganisms. Through this mutually beneficial relationship, the mammals are able to digest cellulose into a form of carbohydrate they can use, as well as other digestive benefits, while the microorganisms receive food and shelter.

Other orders of animals that are closely related to ungulates are:

Ungulate features

The word "ungulate" comes from the Latin word ungula, meaning "hoof." A hoof is a claw or nail that protects the toe and enables it to support the weight of the animal. Ungulates stand and run on the tips of their toes. Most of the weight is supported by the hoofs, with the result that the form of locomotion of ungulates is described as "unguligrade" (rather than "digitigrade," where the toes touch the ground, or "plantigrade," where the entire foot is on the ground, as in humans) (Huffman 2006). This plus modifications in the bones of the legs lengthen the legs, which provides for faster running. It is thought that the ungulates evolved on grasslands where the ability to run quickly is of vital importance in escaping predators (UCMP 2006).

Most ungulates are herbivores, eating plants. Some are grazers, eating grass, and some are browsers, eating leaves of trees and other plants. Many ungulates have large, complexly grooved molar teeth to grind their food. In most, the canine teeth are reduced. A few ungulates, such as the pigs, are omnivores, eating both plant and animal foods.

Perissodactyla: Odd-toed ungulates

Main article: Odd-toed ungulate
Odd-toed ungulates
00296 zebra.jpg
Plains Zebras, Equus quagga
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Perissodactyla
Owen, 1848

In the Perissodactyla, the odd-toed ungulates, the central axis of the foot passes through the third toe. In rhinoceroses, the first and fifth toes are lost and the animal walks on the remaining three toes. In horses, only the third toe remains and supports the whole weight of the animal. Tapirs have four toes on their front feet and three on their hind feet.

Evolution

The odd-toed ungulates arose in what is now North America in the late Paleocene, less than 10 million years after the dinosaurs died out. By the start of the Eocene (55 million years ago), they had diversified and spread out to occupy several continents. The horses and tapirs both evolved in North America; the rhinoceroses appear to have developed in Asia from tapir-like animals and then spread to the Americas during the middle Eocene (about 45 million years ago).

Baird's tapir, Tapirus bairdii

There were 12 families categorized from the fossil record, of which only three survive. These families were very diverse in form and size; they included the enormous Brontotheres and the bizarre Chalicotheres. The largest perissodactyl, an Asian rhinoceros called Paraceratherium, reached 11,000 kg (12 tons), more than twice the weight of an elephant.

Perissodactyls were the dominant group of large terrestrial browsers right through the Oligocene. However, the rise of grasses in the Miocene (about 20 million years ago) saw a major change: the even-toed ungulates with their more complex stomachs were better adapted to a coarse, low-nutrition diet, and soon rose to prominence. Nevertheless, many odd-toed species survived and prospered until the late Pleistocene (about 10,000 years ago) when they faced the pressure of human hunting and habitat change.

Today, there are only 19 species of odd-toed ungulates still living and all of them are in danger of extinction except for the horse and the donkey, which have been domesticated (UCMP 2006).

Perissodactyla families

  • Tapiridae – Tapirs. Southeast Asia, Central and South America. 4 species
  • Rhinocerotidae – Rhinoceroses. Africa and southern Asia. 5 species
  • EquidaeHorse family (horses, donkey, zebras, onager). Africa, Europe, and Asia. 9 or 10 species.

Artiodactyla: Even-toed ungulates

Main article: Even-toed ungulate
Even-toed ungulates

{{{caption}}}
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Owen, 1848


In Artiodactyla, even-toed ungulates, the axis of the leg passes between the third and fourth toes. The weight of most even-toed ungulates is born evenly on the third and fourth toe of each foot with the other toes being absent, or vestigial in the case of most deer. Hippopotamuses and pigs have four functional toes on each foot (Nowak 1983).

Except for hippopotamuses, peccaries, and pigs, all even-toed ungulates digest their food by the process of rumination. Their stomachs are divided into chambers, three for camels and mouse deer and four for the other families (Nowak 1983). After food is swallowed, it is kept in the first chamber for a while where it is partly digested with the help of microorganisms, bacteria, and protists. In this symbiotic relationship, the microorganisms break down the cellulose in the plant material into carbohydrates, which the ungulate can digest. Both sides receive some benefit from this relationship. The microorganisms get food and a place to live and the ungulate gets help with its digestion. The partly digested food is then sent back up to the mouth where it is chewed again and sent on to the other parts of the stomach to be completely digested. The microorganisms themselves are also digested, providing proteins and other nutrients, but not before the community of microorganisms has had a chance to reproduce and give rise to a new generation so the relationship can continue (Lott 2003). The process also generates heat, which can help to keep the ungulate warm, and breaks down plant toxins, which permits plants that are poisonous to other animals to be eaten (Voelker 1986).

Many even-toed ungulates have horns or antlers.

Evolution

As with many mammal groups, even-toed ungulates first appeared during the Early Eocene (about 54 million years ago). In form, they were rather like today's chevrotains: small, short-legged creatures that ate leaves and the soft parts of plants. By the Late Eocene (46 million years ago), the three modern suborders had already developed: Suina (the pig group); Tylopoda (the camel group); and Ruminantia (the antelope group). Nevertheless, artiodactyls were far from dominant at that time: the odd-toed ungulates were much more successful and far more numerous. Even-toed ungulates survived in niche roles, usually occupying marginal habitats, aided by their complex digestive systems, which allowed them to survive on lower-grade feed.

The appearance of grasses during the Eocene and their subsequent spread during the Miocene (about 20 million years ago) saw a major change: grasses are very difficult to digest and the even-toed ungulates with their highly-developed stomachs were better able to adapt to this coarse, low-nutrition diet. They gradually replaced the odd-toed ungulates as the dominant terrestrial herbivores.

There are over 200 species of even-toed ungulates living today. Some are endangered due to hunting and loss of habitat. On the other hand, many species are doing well and some have expanded their ranges due to being introduced to new locations by humans.

African buffalo, Syncerus caffer

Artiodactyla families

  • Suidae – Pigs. Africa, Asia, and Europe.
  • Tayassuidae – Peccaries. North and South America.
  • Hippopotamidae – Hippopotamuses. Africa.
  • Camelidae – Camels, llamas. Africa, Asia, and South America.
  • Tragulidae – Mouse deer or chevrotains. Africa and Asia.
  • Cervidae – Deer, elk, moose. North and South America, Europe, Asia, northern Africa.
  • Moschidae – Musk deer. Asia.
  • Giraffidae – Giraffe and okapi. Africa.
  • Antilocapridae – Pronghorn. North America.
  • BovidaeAntelope, buffalo, cattle, goats, and sheep. Africa, Europe, Asia, and North America.

References
ISBN links support NWE through referral fees

  • Huffman, B. 2007. The Ultimate Ungulate Page. Retrieved April 2, 2007.
  • Lott, D. F. 2002. American Bison. Berkeley: University of California Press
  • Nowak, R. M., and J. L. Paradiso. 1983. Walker's Mammals of the World. Baltimore: Johns Hopkins University Press.
  • University of California Museum of Paleontology (UCMP). 2006. Ungulates: Hoofed Mammals. Retrieved April 2, 2007.
  • Voelker, W. 1986. The Natural History of Living Mammals. Medford, NJ: Plexus Publishing.

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