CLASS Mammalia: mammals. Homeotherms (warm-blooded). They possess mammary glands. Body generally covered with hair. Developed brain.

SUBCLASS Prototheria: prototherians. Oviparous mammals.

ORDER Monotremata: only one orifice for the digestive, reproductive and excretory systems. 2 families and 3 species.

FAMILY Tachyglossidae: echidnas. Narrow snout modified in a beak with a protractile tongue to capture ants. Hair modified in spines. Australia, Tasmania and New Guinea. 2 genera, 2 species: Tachyglossus aculeatus (Australian echidna) and Zaglossus bruijnii (long-beaked echidna).
FAMILY Ornithorhynchidae: platypus. Amphibian mammal, with a duck bill and poisonous spurs in the hind limbs (only males). Australia. 1 species, Ornithorhynchus anatinus.

SUBCLASS Theria: the rest of mammals.

INFRACLASS Metatheria (Marsupialia): marsupials. Abdominal bag where they breed their progeny. Only one orifice for the digestive, reproductive and excretory systems. 19 families and some 260 species.

ORDER Dasyuromorphia: Australasian carnivore marsupials. 3 families.

FAMILY Dasyuridae: includes marsupial mice and Tasmanian Devil. 17 genera.
FAMILY Myrmecobiidae: 1 species, Myrmecobius fasciatus (numbat). Diurnal.
FAMILY Thylacinidae: 1 species, Thylacinus cynocephalus (Tasmanian or marsupial wolf). Extinct.

ORDER Didelphimorphia: 1 family.

FAMILY Didelphidae: American opossums: opossums, mouse opossums, woolly opossums, water opossums or yapoks, etc. 15 genera.

SUBFAMILY Caluromyinae
SUBFAMILY Didelphinae

ORDER Diprotodontia: only two incisors in the lower jaw. 10 families.

FAMILY Acrobatidae: 2 genera, 2 species. Pygmy Glider (Acrobates pygmaeus) and feathertail glider (Distoechurus pennatus).
FAMILY Burramyidae: pygmy possums. 2 genera.
FAMILY Macropodidae: kangaroos, tree kangaroos and wallabies. Herbivores. 14 genera and some 50 species.
FAMILY Petauridae: gliding and striped possums. 3 genera.
FAMILY Phalangeridae: brush-tailed possums and cuscuses. Tree dwellers. 3 genera.
FAMILY Phascolarctidae: koalas. 1 species, Phascolarctos cinereus. Tree dweller, feeds on Eucalyptus leaves.
FAMILY Potoroidae: rat-kangaroos. Marsupial musky rats, potoruses and bettongs. Closely related to kangaroos. 3 genera.
FAMILY Pseudocheiridae: ringtail possums and great gliders. 3 genera.
FAMILY Tarsipedidae: 1 species, Tarsipes rostratus (honey possum).
FAMILY Vombatidae: wombats. 2 genera, 3 species.

ORDER Microbiotheria: 1 family.

FAMILY Microbiotheriidae: 1 species, Dromiciops australis (colocolo or monito del monte). Southern Chile.

ORDER Notoryctemorphia: 1 family.

FAMILY Notoryctidae: 1 species, Notoryctes typhlops (marsupial mole). Moves "swimming" below the sand.

ORDER Paucituberculata: 1 family.

FAMILY Caenolestidae: shrew opossums. South America. 3 genera, 7 species.

ORDER Peramelemorphia: bandicoots. Omnivores. 2 families.

FAMILY Peramelidae: bandicoots and bilbies. 4 genera.
FAMILY Peroryctidae: New Guinean spiny bandicoots. 3 genera.

INFRACLASS Eutheria (Placentalia): placental mammals.

ORDER Edentata (Xenarthra): edentates, meaning "toothless". Despite their name, only anteaters lack teeth. Armadillos and sloths have rootless molars that grow throughout their lives. America (from southern USA to the southern tip). 4 families and 29 species.

FAMILY Bradypodidae: three-fingered sloths. Tree dwellers and herbivores. 1 genus.
FAMILY Dasypodidae: armadillos. Body covered dorsally by bony shields with a horny (keratinous) cover. They eat insects, other invertebrates, small vertebrates and foliage. 20 species.
FAMILY Megalonychidae: two-fingered sloths. Tree dwellers and herbivores. 1 genus.
FAMILY Myrmecophagidae: anteaters. They feed on ants and termites. 3 genera, 4 species.

ORDER Insectivora: insectivores. They feed mainly on insects. Worldwide except Australia and New Zealand. 6 families and 400 species.

FAMILY Chrysochloridae: golden moles. Africa. 18 species.
FAMILY Erinaceidae: erizos. 17 species.

SUBFAMILY Erinaceinae: spiny hedgehogs. Europe, Asia and Africa.
SUBFAMILY Hylomyinae: moonrats. No spines. Southeastern Asia.

FAMILY Solenodontidae: solenodons. They inject toxic saliva to their prey. Cuba and La Española. 1 genus, 2 species at the edge of extinction.
FAMILY Soricidae: shrews. At least two species inject poisonous saliva to their prey. America, Europe, Asia and Africa. 250 species.
FAMILY Talpidae: moles, shrew-moles, and desmans. Europe, Asia and North America. 29 species.
FAMILY Tenrecidae: tenrecs (Madagascar) and otter shrews (Central Africa). Similar to hedgehogs.

ORDER Scandentia: 1 family.

FAMILY Tupaiidae: tree shrews. Eastern India and southeastern Asia. 6 genera and 19 species.

ORDER Dermoptera: 1 family.

FAMILY Cynocephalidae: flying lemurs or colugos. Herbivores. Southeastern Asia. 1 genus, 2 species.

ORDER Chiroptera: bats. Distributed worldwide. 18 families and 977 species.

SUBORDER Megachiroptera: herbivores. 1 family.

FAMILY Pteropodidae: Old World fruit-eating bats and flying foxes. Europe, Asia, Africa and Australia. 41 genera, 163 species.

SUBORDER Microchiroptera: echolocalizing bats. Insectivores. 17 families.

FAMILY Emballonuridae: sac-winged, sheath-tailed, and ghost bats. 49 species.
FAMILY Craseonycteridae: Kitti's hog-nosed bat or bumblebee bat. Thailand. 1 species, Craseonycteris thonglongyai.
FAMILY Rhinopomatidae: mouse-tailed bats. Africa and Asia. 1 genus, 3 species.
FAMILY Megadermatidae: false vampires. Africa, Asia and Australia. 4 genera, 5 species.
FAMILY Nycteridae: slit-faced or hollow-faced bats. Africa and Asia. 14 species.
FAMILY Rhinolophidae: Old World horseshoe bats. 63 species.
FAMILY Mormoopidae: naked-backed bats. America. 2 genera, 8 species.
FAMILY Mystacinidae: New Zealand short-tailed bats. 2 species.
FAMILY Noctilionidae: mastiff or bulldog bats. America. 1 genus, 2 species.
FAMILY Phyllostomidae: New World leaf-nosed bats. Includes the three vampire species. 51 genera, 152 species.
FAMILY Furipteridae: smoky or thumbless bats. America. 2 genera, 2 species.
FAMILY Myzopodidae: Old World sucker-footed bats. Madagascar. 1 species.
FAMILY Natalidae: funnel-eared or long-legged bats. America. 1 genus, 5 species.
FAMILY Thyropteridae: disc-winged bats. America. 1 genus, 2 species.
FAMILY Molossidae: free-tailed bats. America. 13 genera, 89 species.

SUBFAMILY Tomopeatinae
SUBFAMILY Molossinae

FAMILY Vespertilionidae: common bats. Worldwide. 43 genera, 350 species.

SUBFAMILY Vespertilioninae
SUBFAMILY Miniopterinae
SUBFAMILY Myotinae
SUBFAMILY Muriniae
SUBFAMILY Kerivoulinae

FAMILY Hipposideridae: Old World leaf-nosed bats. 66 species.

ORDER Primates: the most advanced mammals. Large brain, 5 fingers in the 4 limbs. Distributed worldwide. 13 families and some 200 species.

SUBORDER Strepsirhini: prosimians. Madagascar, Continental Africa and India. 7 families.

FAMILY Lemuridae: lemurs.
FAMILY Cheirogaleidae: dwarf and mouse lemurs.
FAMILY Indridae: indris, avahis and sifakas.
FAMILY Daubentoniidae: aye-aye.
FAMILY Galagonidae: galagos, bushbabies.
FAMILY Loridae: lorises and pottos.
FAMILY Megaladapidae: sportive or weasel lemurs.

SUBORDER Catarrhini: Old World monkeys, hominids and gibbons. Narrow nasal bone. 3 families.

FAMILY Cercopithecidae: Old World monkeys.

SUBFAMILY Cercopithecinae: cercopithecins, baboons and macaques.
SUBFAMILY Colobinae: colobus and langurs.

FAMILY Hominidae: humans, gorillas, chimpanzees, pygmy chimpanzees (bonobos) and orangutans.
FAMILY Hylobatidae: gibbons.

SUBORDER Platyrrhini: New World monkeys. Wide nasal bone, thumb not completely opposable. 2 families.

FAMILY Callitrichidae: marmosets and tamarins.
FAMILY Cebidae: cebids.

SUBFAMILY Alouattinae
SUBFAMILY Aotinae
SUBFAMILY Atelinae
SUBFAMILY Callicebinae
SUBFAMILY Cebinae
SUBFAMILY Pitheciinae

SUBORDER Tarsii: 1 family.

FAMILY Tarsiidae: tarsiers. Southeastern Asia. 1 genus, 4 species.

ORDER Carnivora: carnivores. In general predators, with developed teeth. Distributed worldwide. 12 families and 270 species.

SUBORDER Fissipedia: 9 families.

FAMILY Canidae: canids. Dogs, wolves, foxes and jackals. Adapted to fast persecution. Worldwide. 13 genera. Bat-eared foxes (Otocyon megalotis) and raccoon dogs (Nyctereutes procyonoides) are more insectivorous.
FAMILY Felidae: felids. The most carnivorous. They are usually divided into big cats or pantherids, small cats or felines, and cheetah.
FAMILY Herpestidae: mongooses and suricats (meerkats).

SUBFAMILY Galidiinae
SUBFAMILY Herpestinae

FAMILY Hyaenidae: hyenas and aardwolves. 3 genera, 4 species.
FAMILY Mephitidae: skunks. America.
FAMILY Mustelidae: weasels, martens, wolverines, minks, ferrets, otters, badgers. Worldwide except Australia.
FAMILY Procyonidae: raccoons, coatis, olingos, kinkajous, lesser panda. Omnivores. America.
FAMILY Ursidae: bears and pandas. In general omnivores. Worldwide.
FAMILY Viverridae: genets and civets. They are usually divided into true civets, Madagascar civets, palm civets and ringed palm civets. Africa and Asia.

SUBORDER Pinnipedia: walruses, sea lions and seals. Limbs modified in paddles for swimming. Generally marine and feed mainly on fish. 3 families and 34 species.

FAMILY Odobenidae: walruses. Long tusks. They lack external ears. Hind limbs can be rotated for use in terrestrial locomotion. Cold Atlantic waters.
FAMILY Otariidae: sea lions (5 species) and fur seals (9 species). External ears. Hind limbs can be rotated for use in terrestrial locomotion. Pacific.
FAMILY Phocidae: seals. No external ears. Hind limbs can not be rotated for use in terrestrial locomotion. Widely distributed.

ORDER Cetacea: whales and dolphins. Forelimbs modified in paddles, hindlimbs absent. No external ears. The respiratory system opens in a hole (spiracle), single or double, at the back side of the head. Tail divided in two lobes. Distributed worldwide. 10 families and 78 species.

SUBORDER Mysticeti: baleen whales. Two spiracles. They preserve a residue of pelvis and hindlimbs. 3 families.

FAMILY Balaenidae: right whales. No dorsal fin. Long and narrow baleen, upper jaw is arched.
FAMILY Balaenopteridae: rorquals. Short triangular baleen. Grooves in the throat. Dorsal fin. Includes blue whale (Balaenoptera musculus) and humpback whale (Megaptera novaeangliae).
FAMILY Eschrichtiidae: grey whale (Eschrichtius robustus). No dorsal fin. Small hunches.

SUBORDER Odontoceti: tooth whales. One spiracle. 7 families.

FAMILY Delphinidae: sea dolphins, killer whales (Orcinus orca) and pilot whales (genus Globicephala). Abundant and widely distributed.
FAMILY Lipotidae: 1 species, Lipotes vexillifer (Yangtze river dolphin).
FAMILY Monodontidae: beluga (Delphinapterus leucas) and narwhal (Monodon monoceros). Flat snout. Dorsal fin reduced or absent. Male narwhal has a largely developed tooth in the upper jaw.
FAMILY Phocoenidae: porpoises. Flat snout.
FAMILY Physeteridae: sperm whales (genus Physeter) and pygmy/dwarf sperm whales (genus Kogia). The biggest odontocetes. Large head containing the spermaceti organ.
FAMILY Platanistidae: freshwater dolphins. Long beak and highly developed dorsal fin. Includes the Amazon River dolphin or boutu (Inia geoffrensis) and the Ganges River dolphin (Platanista gangetica).
FAMILY Ziphiidae: beaked whales. Long snout.

ORDER Perissodactyla: odd-toed ungulates. One or three digits, each covered by a horny (keratinous) hoof. Teeth adapted to grinding. Herbivores. Africa, Asia and Tropical America. 3 families and 18 species.

FAMILY Equidae: 1 genus, Equus. Horses, asses (2 wild species, E. hemionus in Asia and E. africanus in Africa) and zebras (Africa, 3 species, E. zebra or mountain zebra, E. grevyi or Grevy's zebra and E. burchelli or plains zebra). One single digit. The horse (Equus caballus) has established wild populations all around the world from the domestic horse, but the wild form is native of Eurasia and is now extinct.
FAMILY Rhinocerotidae: rhinoceroses. Three digits. One or two horns on the snout lacking a bony core, formed by the agglutination of structures similar to hair. Africa and Southeastern Asia. 4 genera, 5 species.
FAMILY Tapiridae: tapirs. Short trunk formed by the nose and the upper lip. 1 genus, Tapirus, 3 species in South America and 1 in Asia.

ORDER Tubulidentata: 1 family and 1 species.

FAMILY Orycteropodidae: 1 species, Orycteropus afer, aardvark. Primitive and ferocious mammal, resembling a hog with an elongated snout. Feeds on ants and termites. Africa.

ORDER Artiodactyla: even-toed ungulates. Two or four digits, each covered by a horny (keratinous) hoof. Teeth adapted to grinding. Herbivores. Worldwide except Australasia. 10 families and 174 species.

SUBORDER Ruminantia: ruminants, they regurgitate food for chewing again. In general, horns or antlers present in both sexes or only in males.

INFRAORDER Pecora: 3 superfamilies.

SUPERFAMILY Bovoidea: bovines, antelopes and pronghorns. Horns with a bony matrix covered by a horny (keratinous) hollow case. 2 families.

FAMILY Antilocapridae: 1 species, Antilocapra americana (pronghorn). Resembles an antelope. Horny case branched in males, moulted annually. North America.
FAMILY Bovidae: bovines and antelopes. The biggest group of artiodactyls. Perennial horns. Worldwide except South America and Australia (save domestic species). 107 species.

SUBFAMILY Aepycerotinae: 1 species, Aepyceros melampus (impala).
SUBFAMILY Alcelaphinae: hartebeests, wildebeests, and topis.
SUBFAMILY Antilopinae: antelopes and gazelles.
SUBFAMILY Bovinae: bisons, buffalos, cattle, nyalas, bongo, kudus, sitatunga, eland and bushbuck.
SUBFAMILY Caprinae: goats, sheep, bighorn, chamois.
SUBFAMILY Cephalophinae: duikers. 1 genus, Cephalophus.
SUBFAMILY Hippotraginae: sable and Roan antelopes, oryx, waterbucks.
SUBFAMILY Reduncinae: reedbucks. 1 genus, Redunca.

SUPERFAMILY Cervoidea: 2 families.

FAMILY Cervidae: deer. Bony antlers moulted annually, except in the Chinese water deer. Females lack antlers, except in reindeer. America, Europe, Asia and Northern Africa. 39 species.

SUBFAMILY Cervinae: deer and fallow deer.
SUBFAMILY Hydropotinae: 1 species, Hydropotes inermis (Chinese water deer).
SUBFAMILY Muntiacinae: muntjacs.
SUBFAMILY Odocoileinae: moose, reindeer, etc.

FAMILY Moschidae: Old World musk deer. They lack antlers.

SUPERFAMILY Giraffoidea: 1 family.

FAMILY Giraffidae: giraffes and okapis. Bony horns covered with skin. Africa. 2 genera, 2 species.

INFRAORDER Tragulina: 1 family.

FAMILY Tragulidae: chevrotains. No horns.

SUBORDER Tylopoda: 1 family.

FAMILY Camelidae: Bactrian and Arabian camels, llamas, alpacas, guanacos and vicuñas. America, Eurasia and Africa. Mostly domestic. In wild state only some Bactrian camels in Mongolia, escaped Arabian camels in Australia, and guanacos and vicuñas in South America. 3 genera.

SUBORDER Suiformes (Suina): hippopotamuses, pigs, hogs and peccaries. 3 families.

FAMILY Hippopotamidae: hippopotamuses. Four digits. Africa. 2 genera, 2 species.
FAMILY Suidae: Old World pigs (8 species): domestic pig, boars, hogs and babirusas.
FAMILY Tayassuidae: New World peccaries (3 genera, 3 species).

ORDER Pholidota: body covered with imbricated horny (keratinous) scales. Asia and Tropical Africa. 1 family and 7 species.

FAMILY Manidae: pangolins. 1 genus, Manis.

SUBFAMILY Maninae: Asian pangolins. 3 species.
SUBFAMILY Smutsiinae: African pangolins. 4 species.

ORDER Rodentia: rodents. Comprises 40% of all mammalian species. Two pairs of sharp incisors for gnawing. High reproductive and adaptive capacities. Worldwide. 2 suborders, differentiated by morphology of the insertion area for the lower jaw masseter muscles. 29 families and 1,738 species.

SUBORDER Hystricognathi: 18 families.

FAMILY Abrocomidae: chinchilla rats. South America. 1 genus, 3 species.
FAMILY Agoutidae: pacas. Central and South America. 1 genus, 2 species.
FAMILY Bathyergidae: African mole rats. 5 genera, 12 species. Includes the naked mole rat (Heterocephalus glaber).
FAMILY Capromyidae: hutias. West Indies, specially Cuba. 8 genera, 20 species, probably half of them extinct.
FAMILY Caviidae: cavies or South American Guinea pigs. 5 genera, 14 species.

SUBFAMILY Caviinae: cavies and Guinea pigs.
SUBFAMILY Dolichotinae: maras or Patagonian cavies or hares.

FAMILY Chinchillidae: chinchillas and viscachas. South America. 3 genera, 6 species.
FAMILY Ctenomyidae: tuco-tucos. South America. 1 genus, 38 species.
FAMILY Dasyproctidae: agoutis and acouchis. Tropical America. 2 genera, 13 species.
FAMILY Dinomyidae: 1 species, Dinomys branickii (pacarana or false paca). North Andes.
FAMILY Echimyidae: American spiny rats. Tropical America. 20 genera, 78 species.

SUBFAMILY Dactylomyinae
SUBFAMILY Echimyinae
SUBFAMILY Eumysopinae

FAMILY Erethizontidae: New World porcupines. 4 genera, 12 species.
FAMILY Heptaxodontidae: extinct.
FAMILY Hydrochaeridae: 1 species, Hydrochaeris hydrochaeris (capybara). The largest living rodent. Tropical America.
FAMILY Hystricidae: Old World porcupines. Africa and Asia. 3 genera, 11 species.
FAMILY Myocastoridae: 1 species, Myocastor coypus (nutria or coypu). Native of South America but introduced in Europe and the USA.
FAMILY Octodontidae: degus, coruros, rock rats. Peru, Chile, Bolivia and Argentina. 6 genera, 9 species.
FAMILY Petromuridae: 1 species, Petromus typicus (African rock rat). Southwestern Africa.
FAMILY Thryonomyidae: cane rats or grasscutters. Subsaharan Africa. 1 genus, 2 species.

SUBORDER Sciurognathi: 11 families.

FAMILY Aplodontidae: 1 species, Aplodontia rufa (mountain beaver). West coast of North America.
FAMILY Anomaluridae: scaly-tailed squirrels. Central Africa. 3 genera, 7 species.
FAMILY Castoridae: beavers. North America, North Eurasia. 1 genus, 2 species.
FAMILY Ctenodactylidae: gundis. Northern Africa. 4 genera, 5 species.
FAMILY Dipodidae: jerboas, birch mice, jumping mice. Northern Africa, Eurasia and North America. 15 genera, 51 species.

SUBFAMILY Allactaginae
SUBFAMILY Cardiocraniinae
SUBFAMILY Dipodinae
SUBFAMILY Euchoreutinae
SUBFAMILY Paradipodinae
SUBFAMILY Sicistinae
SUBFAMILY Zapodinae

FAMILY Geomyidae: pocket gophers. North and Central America. 5 genera, 35 species.
FAMILY Heteromyidae: pocket mice, kangaroo rats. From Southern North America to Northern South America. 6 genera, 59 species.

SUBFAMILY Dipodomyinae
SUBFAMILY Heteromyinae
SUBFAMILY Perognathinae

FAMILY Muridae: rats, mice, gerbils. Worldwide. 281 genera, 1,325 species.

SUBFAMILY Arvicolinae: voles, lemmings and musk rats. Northern hemisphere except Africa and Southeastern Asia. 26 genera, 143 species.
SUBFAMILY Calomyscinae: Asian mouse-like hamsters. 1 genus, 6 species.
SUBFAMILY Cricetinae: hamsters. South Europe, Central and East Asia. 7 genera, 18 species.
SUBFAMILY Cricetomyinae: pouched rats. Subsaharan Africa. 3 genera, 6 species.
SUBFAMILY Dendromurinae: African climbing mice. 8 genera, 23 species.
SUBFAMILY Gerbillinae: gerbils and sand rats. Africa, Middle East and Central Asia. 14 genera, 110 species.
SUBFAMILY Lophiomyinae: 1 species, Lophiomys imhausi (mane rat). East Africa.
SUBFAMILY Murinae: Old World rats and mice. Dispersed worldwide. The biggest mammalian subfamily. 122 genera, 529 species.
SUBFAMILY Myospalacinae: zokors. Siberia and North China. 1 genus, 7 species.
SUBFAMILY Mystromyinae: 1 species, Mystromys albicaudatus (white-tailed rat). South Africa.
SUBFAMILY Nesomyinae: Madagascar rats and mice. 7 genera, 14 species.
SUBFAMILY Otomyinae: whistling rats. Africa. 2 genera, 14 species.
SUBFAMILY Petromyscinae: rock mice and marsh climbing mice. South Africa. 2 genera, 5 species.
SUBFAMILY Platacanthomyinae: Malabar spiny mouse and blind tree mouse. India and Southeast Asia. 2 genera, 3 species.
SUBFAMILY Rhizomyinae: bamboo rats and African mole rats. Africa and Asia. 3 genera, 15 species.
SUBFAMILY Sigmodontinae: New World rats and mice. 79 genera, 423 species.
SUBFAMILY Spalacinae: blind mole rats. East Mediterranean. 2 genera, 8 species.

FAMILY Myoxidae (Gliridae): dormice. Eurasia and Africa. 8 genera, 26 species.

SUBFAMILY Graphiurinae
SUBFAMILY Leithiinae
SUBFAMILY Myoxinae

FAMILY Pedetidae: 1 species, Pedetes capensis (springhare). South Africa.
FAMILY Sciuridae: squirrels and marmots. Worldwide except Australia, Southern South America and some desert regions.

SUBFAMILY Petauristinae: flying squirrels.
SUBFAMILY Pteromyinae: flying squirrels.
SUBFAMILY Sciurinae: squirrels, marmots and prairie dogs.

ORDER Lagomorpha: lagomorphs. Long incisors constantly growing. A second pair of incisors behind the first. Herbivores. Distributed worldwide except some regions in Southeast Asia. 2 families and 80 species.

FAMILY Leporidae: rabbits and hares. 11 genera, 54 species.
FAMILY Ochotonidae: pikas. North America and Asia. 2 genera, 26 species.

ORDER Macroscelidea: macroscelids. 1 family and 19 species.

FAMILY Macroscelididae: elephant shrews. Africa (Subsaharan and North). 4 genera, 19 species.

ORDER Hyracoidea: hyracoids. They are usually grouped together with elephants and sea cows as "subungulates". 1 family and 7 species.

FAMILY Procaviidae: hyraxes. Subsaharan Africa and Middle East. 3 genera, 7 species.

ORDER Proboscidea: proboscideans. They are usually grouped together with hyraxes and sea cows as "subungulates". 1 family and 2 species.

FAMILY Elephantidae: elephants. Subsaharan Africa, India, Nepal and Southeast Asia. 2 genera, 2 species.

ORDER Sirenia: sirenians (sea cows). They are usually grouped together with hyraxes and elephants as "subungulates". Forelimbs modified to flippers, and hindlimbs reduced to a vestigial pelvis. Herbivores, they feed on algae and sea grass. 2 families and 4 species.

FAMILY Dugongidae: 2 species, Dugong dugon (dugong) and Hydrodamalis gigas (Steller's sea cow). Coast of East Africa, Red Sea, Asia and Australia.
FAMILY Trichechidae: manatees. Gulf of Mexico, Caribbean, north of South America, Amazon and Orinoco basins, and tropical waters of West Africa. 1 genus, 3 species.