MammalA mammal () is a vertebrate animal of the class Mammalia (məˈmeɪli.ə). Mammals are characterized by the presence of milk-producing mammary glands for feeding their young, a neocortex region of the brain, fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors diverged in the Carboniferous Period over 300 million years ago. Around 6,400 extant species of mammals have been described and divided into 29 orders.
PrimatePrimates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys, including apes and humans). Primates arose 85–55 million years ago first from small terrestrial mammals, which adapted to living in the trees of tropical forests: many primate characteristics represent adaptations to life in this challenging environment, including large brains, visual acuity, color vision, a shoulder girdle allowing a large degree of movement in the shoulder joint, and dextrous hands.
Even-toed ungulate_Artiodactyl The even-toed ungulates are mammals belonging to the order Artiodactyla (ˌɑrtioʊˈdæktɪlə, ). They are ungulates—hoofed animals—which bear weight equally on two (an even number) of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing posteriorly. By contrast, odd-toed ungulates bear weight on an odd number of the five toes. Another difference between the two is that many other even-toed ungulates (except for Suina) digest plant cellulose in one or more stomach chambers rather than in their intestine as the odd-toed ungulates do.
