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A mammal (from Latin mamma 'breast') [1] is a vertebrate animal of the class Mammalia (/ m ə ˈ m eɪ l i. ə /).Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle ear bones.
In 1997, the classification of mammals was revised by Malcolm C. McKenna and Susan K. Bell. [10] The Classification of Mammals Above the species level, here referred to as the "McKenna/Bell classification", is a comprehensive work on the systematics, relationships, and occurrences of all mammal taxa, living and extinct, down through the rank of ...
Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad 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.
In zoology, mammalogy is the study of mammals – a class of vertebrates with characteristics such as homeothermic metabolism, fur, four-chambered hearts, and complex nervous systems. [1] Mammalogy has also been known as mastology, theriology, and therology.
Cetartiodactyla is a large order of hoofed mammals, the even-toed ungulates, and aquatic mammals, cetaceans. Cetacea was found to be nested within "Artiodactlya" and has now been moved into that order, whose name is now Cetartiodactyla. [2] Even-toed ungulates are found nearly world-wide, although no species are native to Australia or Antarctica.
Most mammals are viviparous, giving birth to live young. [1] However, the five species of monotreme, the platypuses and the echidnas, lay eggs. The monotremes have a sex determination system different from that of most other mammals. [2] In particular, the sex chromosomes of a platypus are more like those of a chicken than those of a therian ...
Mammaliaformes ("mammalian forms") is a clade of synapsid tetrapods that includes the crown group mammals and their closest extinct relatives; the group radiated from earlier probainognathian cynodonts during the Late Triassic. [1]
Marsupials have the typical characteristics of mammals—e.g., mammary glands, three middle ear bones, (and ears that usually have tragi, [3] varying in hearing thresholds [4]) and true hair. [5] There are, however, striking differences as well as a number of anatomical features that separate them from eutherians .