Artiodactyl Mammals

These are mammals belonging to the taxonomic order Artiodactyla (which means “even-toed Ungulates”).  They usually have two or four hoofed toes on each foot (the peccary is an exception).  This order is remarkably large and diverse including around 220 species from 10 families.  There are also extinct animals from the order.
Families in this order include:

  • Tayassuidae eg. Chacoan Peccary (Catagonus wagneri)
  • Antilocapridae eg. Pronghorn Antelope (Antilocarpa americana)
  • Camelidae eg. Dromedary Camel (Camelus dromedarius)
  • Hippopotamidae eg. Hippopotamus (Hippopotamus amphibius)
  • Moschidae eg. Musk Deer (Moschus chrysogaster)
  • Suidae eg Domestic Pig (Sus scrofa)
  • Tragulidae eg. Mouse Deer (Tragulus napu)
  • Giraffidae eg. Okapi (Okapia johnstoni), Giraffe (Giraffa camelopardalis)
  • Cervidae. eg. Fallow Deer (Dama dama), Moose (Alces alces)
  • Bovidae eg. Black Wildebeest (Connochaetes gnou), Mountain Gazelle (Gazella gazelle), Bison (Bison bison), Mountain Goat (Oreamnos americanus)

They are considered to be the most successful large herbivores worldwide.  Artiodactyls occur naturally on all continents except Antarctica and Australia and the order contains most domesticated agricultural mammals.  

Habitat and locomotion
Most live in open habitats, such as plains , savannas, and meadows but others dwell in forests and in mountainous regions. One group (the Hippos) is semi-aquatic.  All species require vast quantities of vegetation for grazing.   
Within the order can be found some of the fastest-running mammals, and some of the slower species such as pigs and hippos.

Physical characteristics
Most species have some form of weaponry, horns and antlers are present in some families, whilst others have tusks or canines. The number of teeth is variable. Most artiodactyls have modified stomachs, the exceptional case being that of antelope and deer, which have four-chambered stomachs. This is known as an adaptation that allows members of these groups to make use of microorganisms to decompose cellulose (plant tissue that is indigestible by mammals) into digestible material.



Artiodactyls are native to all continents except Australia and Antarctica.
The three suborders are:

  1.   Suiformes (pigs and warthogs, peccaries and hippopotamus)
  2.   Tylopoda
  3.   Ruminantia

Suiformes

These are non ruminants. There were 12 families in the suborder, but nine are now extinct. The living three families are:

Tayassuidae
These are peccaries, occur mostly in South America, but extend through central America and into parts of the USA.
They are similar to pigs in many ways, but also differ in a number of ways Most obvious are differences in the canine tooth which is a short, straight tusk in peccaries, but develops into a longer curved tusk in pigs. The non ruminating stomach has three chambers, and is more complex than in pigs. There are only two digits or toes on the feet (pigs only walk on two digits but have other digits present).
There are three living genera (Tayassu, Catagonus and Pecari), and other extinct genera.
The sub order Dicotylidae is an old name which has variously been used as both a sub genus and family name with pecarries.

Suidae
These are the true pigs and hogs. There are sixteen living species, and some extinct ones. They originally occurred across Eurasia, from Europe to the Philippines and parts of Africa; but the species Sus scrofa, was domesticated and spread much more widely by man, from the earlies times of human history.
They are solid animals varying from 50cm to around 2metres long. The upper canine teeth grow out and curve backwards creating an elongated tusk. They are omnivores, non ruminants, and have a two chambered stomach.

Hippopotamidae
Hoppopotami were once widespread through Eurasia, but no fossils have been found in the Americas or Australia.  There are a number of extinct species in the family, differentiated best on dental differences. Size is not a significant distinguishing factor as there are extinct small species of both living genera.
Only two living species exist in this family:

  • Common Hippopotamus (Hippopotamus amphibius), widespread south of the Sahara, across Africa; toes of foot are joined to form an enlarged structure, nostrils and eyes are arranged such that the head can sit above the water while the rest of the body is still submerged, so it is well adapted to see &and hear while the body is submerged.
  • Pygmy Hippopotamus (Choeropsis liberiensis or Hexaprotadon liberiensis ) from limited parts of West Africa -toes are separated more than on the common hippo.
    Thought to be more closely related to an extinct family (Anthracotheridae), than either Tayassuidae or Suidae. Anthracotheridae animals were large, pig like, and probably aquatic.


Tylopoda

This sub order has only one Family: Camelidae. They include Camels, Llamas and Vicunas. There are two species of camels – Camelus ferus and Camelus dromaderius. There are two forms of Llama (Lama guanicoe) -the Alpacca and the Llama. The Vicguna (Vicugna vicugna) looks a little like a small Llama, and was once included in the same genus as Llama
Living species have a thickened large pad of connective tissue on the bottom of their feet, which is an adaptation for waling in soft, sandy soils. Their feet are quite different to other ungulates, in that the two toes or digits on the feet will sit almost flat on the ground, and rather than hooves, the distal phlanges have nails on their upper surface. Extinct camel species also have two digits on their feet, but unlike living camelids, they are thought to have had true hooves. Camels ruminate (ie. Regurgitate and rechew) their food, but are different to true ruminants in that their stomach has only three chambers.

Ruminantia

This suborder is characterized by a series of traits including head ornamentation such as horns or antlers in most of the groups, missing upper incisors, often (but not always) reduced or absent upper canines, selenodont cheek teeth (seleno- moon shaped, -dont teeth), a 3 or 4-chambered stomach, and third and fourth metapodials usually partially or completely fused.
There are two sub groups (ie. Infraorders) within the Rumminatia. They are the Tragulina which do not have horns, and the Pecora, which do have horns.
The suborder Ruminantia includes 6 families:

  1.     Tragulidae: Chevrotains or mouse deer
  2.     Giraffidae: Giraffes and Okapi
  3.     Cervidae: Deer
  4.     Moschidae: Musk deer
  5.     Antilocapridae: Pronghorn
  6.     Bovidae: Antelopes, Bison, Goats, Sheep, etc.

        

Tragulidae

Commonly called mouse deer or Chevrotains. They are deer like in appearance, but small -never over 20kg. Adults can sometimes only weigh 1.5 kg.This family does not grow horns, bones in feet do not become fused to form a canon bone until the animal is an adult. There are four chambers in the stomach like other ruminants, but the third chamber in the stomach is less developed than in other Ruminantia. Upper canine teeth can extend down from the mouth forming tusks.They are forest dwellers. Most species are from Asia but one species occurs in central and west Africa.

Giraffidae

There are only two living species: Giraffes and Okapi. They are native to Africa. Both have over developed forequarters, creating a downward sloping back. Both have a long prehensile tongue adapted to feeding. Their digestive system is more efficient than other ruminants because of tongue like papillae in the stomach, which greatly increase the surface area through which food can be absorbed. A pair of skin covered bony knobs develop on the head.

Cervidae

Deer are wide spread, with species indigenous to most parts of the world (excluding Australia). They occur across a wide range of climates and ecosystems from the arctic to tropics, from forests to grasslands.
All species (except one) grow antlers. Antlers unlike horns of cattle, rhinos or other animals, are composed of bone, growing as an extension from the frontal bone in the skull. Antlers typically develop a branching growth. Changes in the animal’s hormones will cause periodic decalcification of the antlers base (where it joins to the skull) causing it to shed (usually in late autumn or winter), after which the antler starts to regrow again. In most species only males have antlers. The reindeer (Rangifera tarandus) is an exception.

Moschidae

Musk deer were previously classified with other deer in Cervidae, but are now considered a separate family. The taxonomy is still not fully settled though. There are nine or more living species, all from Asia.
They resemble mouse deer more than Cervidae in some respects. They do not have antlers or horns, but the upper canines in males will grow to form tusks up to 10cm long. They have a gall bladder, Adult males can excrete a waxy substance (called musk), , from a gland in the abdomen Musk is  used commercially in perfumes and medicines and can sell for tens of thousands of dollars per kg.

Antilocapridae

There is only one living species in this family; the Pronghorn (Antilocapra Americana). The horns are a defining feature being branched, and with skin covering the bony core (as in girrafes). A gall bladder is present. The eye sockets are high in the skull. The feet only have two digits. Another unique characteristic is their ability to run at high speeds. It is one of the fastest mammals, able to reach up to 95km per hour.

Bovidae

There are over 140 species here including Antelopes, Cattle, Bison, Goats, Sheep, Waterbuck, Impala and Wilerbeast. They are indigenous to many parts of the world including America, Asia, Europe and Africa, and adapted to a wide range of climates and environments.
A defining characteristic of bovids, is an unbranched horn which occurs in males of most species and females of some. When both sexes have horns, the male horns are normally thicker and more complex. Horns are a bone attached to the skull covered by a layer of keratin. Some have four horns,