Artiodactyls: General Characteristics, Classification

The artiodactyls they are ungulate placental mammals, whose legs end in hooves, with an even number of functional fingers on each one. The first fossils confirm their existence in the Eocene period, approximately 54 million years ago.

This group of animals make up the order of most numerous mammals, with around 235 species being counted, which present a diversity of sizes, shapes and habitats. They are herbivores, except for some species that feed on small insects.

Artiodactyls have been exploited for economic purposes by humans since prehistoric times. There is evidence that indicates the reindeer as an important element in the survival of Cro-Magnon man , who used its meat for food, its skin for clothing, and its bones to build tools.

Currently these animals have been domesticated, marking a great advance in history. For example, the llama and the camel are used as a means of transportation and for heavy work, the pig and the cow as food, and the sheep in the manufacture of clothing and footwear.

The vast majority are gregarious, thus allowing them to protect themselves from predators and consume a greater amount of forage. Some of its representatives are the giraffe, wild boar and the bull.

General characteristics

Artiodactyls have peculiarities that distinguish them from the other groups into which the animal kingdom is divided. In them the size is variable, the smallest species, the mouse deer, measures 45 cm, while the giraffe can reach 5.5 meters high.

-Physical appearance

Legs

Their toes are present in even numbers (2 or 4), with the exception of Tayasuids which have three on their hind legs. They are covered by keratin, a substance that hardens them and forms the hooves.

Its locomotor axis is between the third and fourth fingers, which tend to be longer and to fuse with each other, forming the cane. The second and fifth fingers are reduced or absent.

Herbivorous mammals do not have the necessary enzyme to break down cellulose in plants, so they use microorganisms to do so. Therefore, in addition to their true stomach, they have at least one extra chamber where this bacterial fermentation takes place .

The number of these “false stomachs” can vary in each species, cows have 4, while pigs have a small one.

Head

It is relatively large, with a long and narrow skull. Some species have horns or antlers, which they use frequently in some social interactions.

The number and type of teeth vary, but the upper incisors are always reduced or absent. The canines are small, although in some they are elongated in the form of fangs. Molars have longitudinal ridges that they use for grinding.

Glands

Some species have a glandular system that emits a characteristic smell, which is used in the marking of the territory and in their social and sexual relationships. These can be located on the head, groin, between the fingers, or in the anal area.

Reproductive organs

The penis is shaped like an “S” and stretches during erection. This sex organ is found under the skin of the belly. The testicles are inside the scrotum and are located outside the body, in the abdomen.

In females, the ovaries are near the pelvic inlet and the uterus is divided in two (uterus bicornis). The number of mammary glands varies, being related to the size of the litter. In some species these join, forming an udder in the inguinal region.

Classification

Antilocapridae

They are an endemic family of North America, whose only species that currently lives is the pronghorn or American antelope. It is a mammal similar to the antelope, it is ruminant, it has a short goat and both sexes have horns on their heads.

Bovidae

In this herbivorous family are included sheep, goats, bulls, among others. Some may have a strong musculature, like the bull, and others are agile to travel long distances quickly, like gazelles.

They live in habitats such as the tundra, desert, or tropical forests. Most species form large groups, with a complex social structure.

Camelidae

This group is made up of three genera: Camelus, which lives in the plains of Asia and Africa, while the Vicugna and Alpaca genera are located in the Andean mountains.

They are herbivorous animals, with a long and thin neck. They do not have hooves, but two toes with strong nails and footpads, on which most of their weight falls.

Cervidae

The legs of the cervidae are thin, having the hooves divided in two. Their neck is long, as is their head, which makes it easier for them to reach the tall leaves of the bushes. Deer and elk are examples of this family.

Giraffidae

Currently there are only two species of this family, both located in Africa, the giraffe and the okapi. Their horns are covered with fur, making them durable. They do not have false hooves and their hind limbs are shorter than the front ones.

Hippopotamidae

Its body is large, legs short and thick. They have four toes, but contrary to the other ungulates, they do not have hooves, these being replaced by the foot pads. Your stomach is divided into three chambers. There are only two species, the common hippo and the pygmy.

Moschidae

They are known as musk deer, because they have glands that secrete a waxy substance with a strong odor, which is used in the cosmetic industry to make perfume and soap.

Males have large fangs that protrude downward and out of their mouths. Their diet is made up of herbs, mosses and lichens.

Suidae

It is made up of wild boars and pigs, making a total of 16 species, distributed throughout Eurasia and Africa, although they have already been introduced to other continents.

These omnivorous feeding ruminant mammals have a large head and very small eyes. Its poor vision is compensated by an excellent development of the sense of smell, which allows it to detect its food and predators.

T ayassuidae

This family is known as pigs or mountain pigs. On their face they have a snout that ends in a kind of characteristic gelatinous disk and very small eyes. To walk they use the central toes of their front legs, the other toes may appear atrophied or be totally absent.

Tragulidae

The stomach of fawns, as this family is also known, has four chambers. Their diet is almost exclusively vegetables, except for the water mouse deer, which also eats small insects.

They lack upper incisor teeth, have short legs and their females give birth to a single young.

References

  1. Alan William Gentry (2018). Artiodactyl mammal. Enclyclopedia Britannica. Taken from: britannica.com
  2. Etnyre, E .; J. Lande; A. Mckenna and J. Berini (2011). Artiodactyla. Animal Diversity Web. Taken from: animaldiversity.org
  3. Wikipedia (2018). Even-toed ungulate. Taken from en.wikipedia.org
  4. Myers, P., R. Espinosa, CS Parr, T. Jones, GS Hammond, TA Dewey. (2018). Artiodactyla classification. Animal Diversity Web. Taken from: animaldiversity.org
  5. Klappenbach Laura (2018). Even-Toed Hoofed Mammals. ThoughtCo. Taken from: thought.com

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