Mammals hear sounds after they are transmitted from the outside world to their inner ears by a chain of three bones, the malleus, incus, and stapes. Two of these, the malleus and incus, are derived from bones involved in jaw articulation in most other vertebrates.
Mammals have hair. Adults of some species lose most of their hair, but hair is present at least during some phase of the ontogeny of all species. Mammalian hair, made of a protein called keratin, serves at least four functions. First, it slows the exchange of heat with the environment (insulation). Second, specialized hairs (whiskers or "vibrissae") have a sensory function, letting the owner know when it is in contact with an object in its external environment. These hairs are often richly innervated and well-supplied with muscles that control their position. Third, through their color and pattern, hairs affect the appearance of a mammal. They may serve to camouflage, to announce the presence of especially good defense systems (for example, the conspicuous color pattern of a skunk is a warning to predators), or to communicate social information (for example, threats, such as the erect hair on the back of a wolf; sex, such as the different colors of male and female capuchin monkeys; presence of danger, such as the white underside of the tail of a whitetailed deer). Fourth, hair provides some protection, either simply by providing an additional protective layer (against abrasion or sunburn, for example) or by taking on the form of dangerous spines that deter predators (porcupines, spiny rats, others).
Mammals feed their newborn young with milk, a substance rich in fats and protein that is produced by modified sweat glands called mammary glands. These glands, which take a variety of shapes, are usually located on the ventral surface of females along paths that run from the chest region to the groin. They vary in number from two (one right, one left, as in humans) to a dozen or more.
Other characteristics found in most mammals include highly differentiated teeth; teeth are replaced just once during an individual's life (this condition is called diphyodonty, and the first set is called "milk teeth); a lower jaw made up of a single bone, the dentary; four-chambered hearts, a secondary palate separating air and food passages in the mouth; a muscular diaphragm separating thoracic and abdominal cavities; highly developed brain; endothermy and homeothermy; separate sexes with the sex of an embryo being determined by the presence of a Y or 2 X chromosomes; and internal fertilization.
The Class Mammalia includes around 5000 species placed in 26 orders (systematists do not yet agree on the exact number or on how some orders are related to others). Mammals can be found in all continents and seas. In part because of their high metabolic rates (associated with homeothermy and endothermy), they often play an ecological role that seems disproportionately large compared to their numerical abundance.
It is the intention that you enjoy and learn about the wonderful creatures about us...and also how we are partly or mostly responsible for some of their inevitable extinction.
Order MONOTREMATA (Monotremes: platypus and echidnas) Families of Monotremata Family Ornithorhynchidae (platypus) Family Tachyglossidae (echidnas or spiny anteaters) Order DIDELPHIMORPHIA (opossums) Order PAUCITUBERCULATA (marsupials) Families of Paucituberculata Family Caenolestidae (shrew-like animals) Order MICROBIOTHERIA (marsupials) Families of Microbiotheria Family Microbiotheriidae (marsupials) Order DASYUROMORPHIA (dasyurids, numbats, anteaters,)Families of Dasyuromorphia Family Dasyuridae (dasyurids) Family Myrmecobiidae (numbat or marsupial anteater) Family Thylacinidae (extinct thylacine or Tasmanian wolf) Order PERAMELEMORPHIA Families of Peramelemorphia Family Peramelidae (bandicoots and bilbies) Family Peroryctidae (Spiny bandicoots) Order NOTORYCTEMORPHIA (marsupial moles) Families of Notoryctemorphia Family Notoryctidae (marsupial moles) Order DIPROTODONTIA (marsupials) Families of Diprotodontia Family Acrobatidae (Feathertail gliders) Family Burramyidae (Pygmy possums) Family Macropodidae (Kangaroos, wallabies, pademelons, quokka, swamp wallaby, tree-kangaroos) Family Petauridae (Striped possum, Leadbeater's possum, and wrist-winged gliders) Family Phalangeridae (Brushtail possums, cuscuses, scaley-tailed possums) Family Phascolarctidae (koalas) Family Potoroidae (Rat-kangaroos, potoroos, bettongs) Family Pseudocheiridae (Ringtail possums, great glider) Family Tarsipedidae (Honey possum, noolbender) Family Vombatidae (Wombats) Order ARTIODACTYLA (antelope, giraffe, camels, pigs, hippos, etc.) Families of Artiodactyla Family Suidae (pigs and hogs) Family Tayassuidae (pig-like animals) Family Hippopotamidae (hippopotamus) Family Camelidae (camels, llamas, alpacas, vicugnas, guanacos) Family Tragulidae (mouse deer, chevrotain) Family Giraffidae (giraffes and okapis) Family Moschidae (musk deer) Family Cervidae (deer) Family Antilocapridae (pronghorn antelope) Family Bovidae ( gazelles, African antelope, buffalo, mountain goats, and domesticated species such as cattle,
sheep, and goats) Order CARNIVORA (carnivores) Superfamily Canoidea (Carnivores) Families of Carnivora Family Canidae (canines) Family Ursidae (bears) Family Otariidae (sea lions, eared seals, fur seals) Family Odobenidae (walrus) Family Procyonidae (raccoons, cacomistles, coatimundis, kinkajous, olingos) Family Mustelidae (weasels, stoats, polecats, ferrets, mink, marten, fishers, tayras, wolverines, grisons, badgers,
skunks, otters, and others) Family Phocidae (earless seals) Superfamily Feloidea Families of Carnivora Family Viverridae (civets, linsangs, genets, palm civets,toddy cats, binturong, fossas) Family Herpestidae (mongooses, meerkats, suricats, fossas) Family Hyaenidae (hyaenas) Family Felidae (cats) Order CETACEA (whales, dolphins, and porpoises) Families of Mysticetes: Balaenidae (right and bowhead whales) Neobalaenidae (pygmy right whale) Balaenopteridae (rorquals) Eschrichtiidae (gray whale) Families of Odontocetes: Physeteridae (sperm whale) Monodontidae (narwhal and white whale) Ziphiidae (beaked whales) Delphinidae (ocean dolphins) Phocoenidae (porpoises) Platanistidae (river dolphins) Order CHIROPTERA (bats) Suborder Megachiroptera
Families of Chiroptera Family Pteropodidae (Old World fruit-eating bats)
Family Rhinopomatidae (long-tailed or mouse-tailed bats) Family Craseonycteridae (bumblebee bat) Family Emballonuridae (sac-winged or sheath-tailed bats) Family Nycteridae (slit-faced or hollow-faced bats) Family Megadermatidae (false vampire bats) Family Rhinolophidae (horseshoe bats or Old-World leaf-nosed bats) Family Noctilionidae (bull-dog or mastiff bats) Family Mormoopidae (naked-backed bats) Family Phyllostomidae (New World leaf-nosed bats) Family Natalidae (funnel-eared or long legged bats) Family Furipteridae (smoky or thumbless bats) Family Thyropteridae (disc-winged bats) Family Myzopodidae (old world sucker-footed bats) Family Vespertilionidae (evening bats) Family Mystacinidae (New Zealand short-tailed bats) Family Molossidae (free-tailed bats) Order DERMOPTERA (colugos) Families of Dermoptera Family Cynocephalus variegatus (Flying Lemur, Colugo) Order HYRACOIDEA (hyraxes) Families of Hyracoidea Family Dendrohyrax dorsalis (Tree Hyrax) Family Heterohyrax brucei (Yellow Spotted Hyrax) Family Procavia capensis (Cape Hyrax) Order INSECTIVORA (Insectivores: shrews, moles, hedgehogs, tenrecs, etc.) Families of Insectivora Family Erinaceidae (hedgehogs and gymnures) Family Talpidae (moles and desmans) Family Solenodontidae (solenodon) Family Tenrecidae (tenrecs) Family Chrysochloridae (Golden moles) Family Soricidae (shrews) Order LAGOMORPHA (rabbits, hares and pikas) Families of Lagomorpha Family Ochotonidae (pikas) Family Leporidae (hares and rabbits) Order MACROSCELIDEA (elephant shrews) Families of Macroscelidea Family Elephantulus brachyrhynchus (short-snouted elephant shrew) Family Elephantulus rufescens (East African Long-Eared Elephant Shrew) Family Rhynchocyon chrysopygus (Golden-Rumped Elephant Shrew) Order PERISSODACTYLA (horses, rhinos, tapirs) Families of Perissodatactyla Family Equidae (horses) Family Tapiridae (tapirs) Family Rhinocerotidae (Rhinoceros) Order PHOLIDOTA (pangolins) Families of Pholidota Family Manidae (pangolins) Order PRIMATES (primates) Suborder Strepsirhini Families of Primates Family Lemuridae (lemurs) Family Cheirogaleidae (dwarf lemurs, mouse lemurs) Family Indridae (indrisoids, avahis, sifakas, indris) Family Daubentoniidae (aye-aye) Family Galagonidae (galagos, bushbabies) Family Loridae (lorises, slow lorises, pottos, angwantibos) Family Megaladapidae (sportive lemurs or weasel lemurs) Suborder Haplorhini Families of Primates Family Tarsiidae (tarsiers) Family Cebidae (cebids, including capuchin monkeys, howlers, many others) Family Cercopithecidae (Old World monkeys and baboons, many others) Family Callitrichidae (marmosets, tamarins) Family Hylobatidae (gibbons and siamangs) Family Hominidae (chimpanzees, gorillas, orangutans, humans) Order PROBOSCIDEA (elephants) Families of Proboscidea Family Elephantidae (elephants and mammoths [extinct]) Loxodonta africana (African Elephant) Elephas maximus (Asian Elephant) Order RODENTIA (rodents) Suborder Sciurognathi Families of Rodentia Family Aplodontidae (mountain beaver, sewellel) Family sciuridae (squirrels) Family Castoridae (beavers) Family Geomyidae (pocket gophers) Family Heteromyidae (kangaroo rats, pocket mice, and allies) Family Dipodidae (birch mice, jumping mice, jerboas) Family Muridae (familiar rates and other rodents) Family Anomaluridae (scaly-tailed squirrels) Family Pedetidae (spring hare, springhaas) Family Ctenodactylidae (gundis) Family Myoxidae (dormice and hazel mice) Suborder Hystricognathi Families of Rodentia Family Bathyergidae (mole rats, blesmols, and rats) Family Hystricidae (Old World porcupines) Family Petromuridae (rock rat or dassie rat) Family Thryonomyidae (cane rats or grasscutters) Family Erethizontidae (New World porcupines) Family Chinchillidae (Chinchillas and viscachas) Family Dinomyidae (pacarana, branick rats, false paca) Family Caviidae (cavies and guinea pigs) Family Hydrochaeridae (capybara) Family Dasyproctidae (agoutis, acouchis) Family Agoutidae (pacas) Family Ctenomyidae (tuco-tucos) Family Octodontidae (degus, coruros, rock rats) Family Abrocomidae (chinchilla rats, chinchillones) Family Echimyidae (spiny rats) Family Capromyidae (hutias, zagouties, cavies, Indian coneys) Family Heptaxodontidae (Quemi, giant hutias) Family Myocastoridae (nutria, coypu) Order SCANDENTIA (tree shrews) Families of Scandentia Subfamily Tupaiinae (tree shrews) Order SIRENIA (dugongs and manatees) Families of Sirenia Family Dugongidae (dugongs and sea cows) Family Trichechidae (manatees) Order TUBULIDENTATA (aardvark) Families of Tubulidentata Family Orycteropodidae (aardvark) Order XENARTHRA (edentates; sloths, armadillos and anteaters) Familes of Xenarthra Family Dasypodidae (armadillos) Family Myrmecophagidae (anteaters) Family Bradypodidae (three toed sloths) Family Megalonychidae (two toed sloths)