Ungulate

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Ungulates, or hoofed mammals, 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).

Ungulates are tremendously important to humans. From earliest times they have been hunted for food. Other species have played important roles as domesticated animals; including sheep (Ovis aries), goats (Capra hircus), pigs (


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

  • Tubulidentata - Aardvark
  • Hyracoidea - Hyraxes
  • Proboscidea - Elephants
  • Sirenia - Sea cows
  • Cetacea - Whales and Dolphins

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. This has the effect of lengthening their legs which helps them to run faster.

Ungulates are typically herbivores, eating plants; some, such as the pigs, are omnivores, eating a variety of foods including meat.

Perissodactyla: odd-toed ungulates

Odd-toed ungulates
00296 zebra.jpg
Plains Zebras
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 tapirs and 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.

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). 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.

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 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.

Today there are only 17 species of odd-toes ungulates still living and all of them are in danger of extinction except for the horse and the donkey (UCMP 2006).


Perissodactyla families

  • Tapiridae - Tapirs. Central and South America. 4 species
  • Rhinocerotidae - Rhinoceroses. Africa and southern Asia. 5 species
  • Equidae - Horses. Africa, Europe, and Asia. 8 species.

Even-toed ungulates

Even-toed ungulates
240px
Rocky Mountain Goat, Oreamnos americanus
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 forth toes.

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.

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, and soon replaced the odd-toed ungulates as the dominant terrestrial herbivores.

Artiodactyla families

  • Suina - Pigs. Africa, Asia, and Europe. 8 species.
  • Tayassuidae - Peccaries. North and South America. 3 species.
  • Hippopotamidae - Hippopotamuses. Africa. 2 species.
  • Camelidae - Camels, llamas. Africa, Asia, and South America. 6 species.
  • Tragulidae - Mouse deer. Africa and Asia. 4 species.
  • Cervidae - Deer, elk, moose. North and South America, Europe, Asia, northern Africa. 38 species.
  • Giraffidae - Giraffe and okapi. Africa. 2 species.
  • Antilocapridae - Pronghorn. North America. 1 species.
  • Bovidae - Antelopes, cattle, goats, sheep. Africa, Europe, Asia, and North America. 128 species.

References
ISBN links support NWE through referral fees

  • Huffman, B. 2006 The Ultimate Ungulate Page Website [1]
  • Nowak, R.M. and Paradiso, J.L. 1983. Walker's Mammals of the World. Baltimore, Maryland, USA : The Johns Hopkins University Press
  • University of California Museum of Paleontology (UCMP) 2006. "Ungulates: Hoofed Mammals"[2]
  • Voelker, W. 1986. The Natural History of Living Mammals. Medford, New Jersey, USA : Plexus Publishing, Inc.

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