Mammals

Article

August 11, 2022

Mammals (lat. Mammalia, from Latin mamma "breast") are vertebrates characterized by the presence of mammary glands with the help of which females produce milk for feeding (breastfeeding) their young, neocortex (region in the brain), fur or hair, and three auditory ossicles. These characteristics distinguish them from reptiles and birds, from which they have been different since the late Triassic, 201–227 million years ago. There are about 5,450 species of mammals. The largest orders are rodents, bats and Soricomorpha (shrews and moles). The next three are primates (humans, apes, and monkeys), ungulates (cetaceans and terrestrial ungulates), and beasts (cats, dogs, pinnipeds, and many others). Mammals are descendants of the synapsids of beastly reptiles, which arose about 300 million years ago. The first mammals in the broadest sense of the word appeared approximately 225 million years ago, during the Triassic period and the dominance of the dinosaurs. Three modern groups of mammals gradually differentiated: marsupials, platypuses and placental mammals. From the originally small nocturnal (nocturnal) mammals, after the great extinction of reptiles at the end of the Mesozoic, they are subject to adaptive radiation and today many life forms live in most ecosystems of the planet Earth.

Body Features

Mammals belong to terrestrial vertebrates (lat. Tetrapoda) within the taxon vertebrates (lat. Vertebrata) and thus they have common features that are not individually listed here. There are a number of characteristics of today's mammals that distinguish them from other vertebrates. The most noticeable features are the mammary glands and hair, but there are also a number of other distinctive features. These are the secondary jaw joint, akinetic and altered synapsid skull, three auditory ossicles, spiral cochlea, extremely pronounced heterodont dental system, strongly developed cerebral hemispheres, alveolar lung structure, muscular diaphragm, erythrocytes without nuclei.

Leather derivatives

First of all, mammals are characterized by fur, a body covering that is essential for thermoregulation. Fur is made of hair, and mammalian hair is made of keratin. It can be of different lengths, densities, colors and patterns, so it can play a role in mimicry or camouflage (eg white rabbit and arctic fox). The fur can be thicker or thinner, and in some species the hair is replaced by scales or spines (eg hedgehogs) and has a defensive role. Certain species