This lifeform is widespread in North America. This lifeform is threatened and might become extinct.

American Bison (Bison bison) was present in great numbers over most of North American prior to the immigration of European settlers. Scientific estimates indicate that at one time there may have been in excess of 50 million of the Plains subspecies roaming its habitat. Additionally, the Bison was also found in wooded areas of the eastern portion of the continent. Because of continuous slaughter, much of it for sport during the advent of the Iron Horse (the train), relatively few animals remain. Many of these are in protected parks and ranges as well as some private herds. This large animal can weigh over 2,000 pounds.

Bison genus contains two species,  the European bison and the North American bison.

Wild Cattle Group (Wild Bovinae) contains the Bison and the various wild cattle that are found in the Old World. The Bison (2 wild species), Bos (5 wild species of cattle), Bubalus (4 species of Asian buffalo), Ovibus (one species, musk ox), and Syncerus (one species of African buffalo), are included in this group for a total of 13 species.

Oxen Group (Family Bovidae) is a very large family of grazing animals that is characterized by having permanent hollow horns. Included in this family are the oxen and cattle, sheep, goats, buffalos, and antelopes. Depending upon the precise delineation of several species, and whether recently extinct species should be counted, there are about 140 species in this family. Several domesticated forms have been recently elevated to full species level. These domesticated forms have been given unique scientific names.

Ever since dinosaurs roamed the earth, there has been a continuous struggle between predators and herbivores. It is interesting to observe the variety of means that Bovidae have used to protect themselves from the carnivore group. Species have developed uniquely on different continents and various defense strategies have evolved.

In North America and in northern Eurasia, several species have become successful by learning to live on mountains beyond the reach of the large cats and wolves. Mountain goats and mountain sheep fall into this category.

In Africa and North America, many species form large herds for protection. These herds provide a feast or famine environment for the predator carnivores. One North American species actually forms circles with head and horns outward for group protection.

In Africa, Eurasia, and North America several species reach significant sizes so that only the most aggressive carnivores dare attack them. The American bison, for example, can be up to two thousand pounds, certainly a challenge for several wolves or a giant mountain lion of two hundred pounds.

The speed of the Antelopes of Africa and North America gives them a chance to outrun their enemies. The protective coloration and small size of the African Dwarf Antelopes and Duikers gives them a chance to hide from their enemies. The horns of most species give them a chance to inflict a mortal wound on any potential enemy. Some authorities suggest that most carnivores feed primarily on the old and the sick, and leave the healthy animals alone.

Many species of Bovidae have been domesticated. Goats and cattle provide milk which in turn provides dairy products such as cream and cheese. Lambs and cattle provide significant amounts of meat. The wool of sheep is important for the clothing industry.

The Bovidae have had many taxonomic revisions and name changes since the time of Linnaeus. Many open questions apply to the relationships of many closely related species and/or various subspecies. The single most confusing issue is the large number of forms that have been domesticated.

It is also difficult to place the various species into tribes that will properly portray the relationships in this family.

To ease study of this group, the domestic cattle, goat, and sheep groups should be separated from their wild relatives. Following is the organization of the tribes and/or groupings used here:

                 TRIBE AND/OR GROUPINGS
                      
      Pronghorn, etcetera         Miscellaneous small tribes
      Duikers                     Cephalophini
      Dwarf Antelopes             Neotragini
      Gazelles                    Antilopini
      Reedbucks and Kob           Reduncini
      Horse Antelopes             Hippotragini
      Hartebeests                 Alcelaphini
      Spiral Horned Group         Tragelaphini
      Cattle and Bison Group      Bovinae
      Domesticated Cattle         Bovinae - domesticated
      Goats                       Caprinae
      Domesticated Goats          Caprinae - domesticated
      Sheep                       Ovinae
      Domesticated Sheep          Ovinae - domesticated

Antelopes comprise a group of tribes containing about ninety worldwide species of which seventy-six are found in Africa. This number of seventy-six was created from the following tabulation of tribes that includes two extinct African species. Because the majority of antelopes are found in Africa, the African species have been tabulated separately from those found in the rest of the world in the following list:

             TRIBE                     AFRICA    NON-AFRICAN
  
    Pronghorn (Antilocapridae)            0         1 (USA)  
    Rhebok (Peleini)                      1            
    Impala (Aepycerotini)                 1                
    Duikers (Cephalophini)               16              
    Dwarf Antelopes (Neotragini)         15              
    Gazelles (Antilopini)                13         10 (?)
    Reedbucks & Kob (Reduncini)           8                
    Horse Antelopes (Hippotragini)        6         1 (Arabia)
    Hartebeests, etcetera (Alcelaphini)   7                
    Spiral Horned (Tragelaphini)          9         2 (India)    
    Totals                               76        14

Perhaps the most significant factor in the large number of species of Antelopes in Africa is the Tsetse fly. These flies carry diseases that infect not only man, but also domesticated cattle. These diseases have curtailed human populations over much of eastern Africa which has in turn permitted large natural concentrations of wildlife to endure.

Pigs, Camels, Sheep, Oxen, Antelopes, and Deer and many other large mammals are combined into a single large group, Order Artiodactyla. Characteristically, the feet of these animals have modified into hoofs with two toes.

Mammals (Class Mammalia), together with the birds, are among the youngest of the classes of animals. In species count, mammals number about fifty-one hundred, trailing reptiles (approximately fifty-five hundred), fish (approximately eighteen thousand), and birds (approximately eighty-six hundred).

There are three sub-types of mammals:

   monotremes, the most primitive:
      Develop in reptilian-like eggs and suckle milk emerging
      (i.e., spiny anteater, duckbilled platypus)

   marsupials
      Newborn emerges very underdeveloped and continue to
      mature in a pouch on its mother's abdomen (i.e., opossums,
      koala, kangaroo)

   placental  
      Embryo develops within the uterus of the female and is
      dependent on a placenta for nutrition and waste removal
      (i.e., humans, lions, monkeys)  

About sixty-five million years ago, the Tertiary era produced thirty-five orders of mammals. Of this number, eighteen have survived to represent Earth's most diversified as well as its most highly developed classification of animals.

Extinction of mammals is fast becoming a serious issue. Duff and Lawson present a list of forty-one extinct species that reached extinction prior to 1800. These forty-one species are not acknowledged in the counts of the various families. Duff and Lawson also present a list of forty-six species including three gazelles, one zebra, one seal, one deer, and one wolf that have probably gone extinct since 1800. These forty-six species are included in the family counts. Science is adding about forty to fifty new species a year to the list. Many of these are the result of divisions of prior species; some are recent discoveries.

Mammals owe their survival to adaptive capabilities that include the ability to exploit whatever sources of food are available to them, as well as their ability to adjust to various climes. Food specialization influenced evolution to such a great extent that the teeth structure can and has been used to provide extensive information on the food needs and various lifestyles of extinct species.

Despite the vast diversity among mammals in terms of size, habitats and adaptations, they share without exception many characteristics such as:  

    a. body hair
    b. mammary glands
    c. certain skull characteristics
    d. four limbs that permit speed
    e. parallel not perpendicular limbs
    f. compartmentalized internal organs
    g. a four-chambered heart and pulmonary circulation

Backboned Animals (Phylum Chordata) are the most advanced group of animals on earth. These animals are characterized by having a spinal cord or backbone. Most members have a clearly defined brain that controls the organism through a spinal cord. Fish, amphibians, reptiles, birds, and mammals are in this phylum.

Currently, some taxonomists believe that the fish should be divided into two groups (sharks and regular fishes) and that there are some other primitive groups in the phylum such as hagfish or lampreys.

Animal Kingdom contains numerous organisms that feed on other animals or plants. Included in the animal kingdom are the lower marine invertebrates such as sponges and corals, the jointed legged animals such as insects and spiders, and the backboned animals such as fish, amphibians, reptiles, birds, and mammals.