Mammalia is a class of animal within the Phylum Chordata. Mammal classification has been through several iterations since Carl Linnaeus initially defined the class. No classification system is universally accepted; McKenna & Bell (1997) and Wilson & Reader (2005) provide useful recent compendiums. Many earlier ideas have been completely abandoned by Linnaeus and modern taxonomists, among these are the idea that bats are related to birds or that humans represent a group outside of other living things. Competing ideas about the relationships of mammal orders do persist and are currently in development. Most significantly in recent years, cladistic thinking has led to an effort to ensure that all taxonomic designations represent monophyletic groups. The field has also seen a recent surge in interest and modification due to the results of molecular phylogenetics.
George Gaylord Simpson's classic "Principles of Classification and a Classification of Mammals" (Simpson, 1945) taxonomy text laid out a systematics of mammal origins and relationships that was universally taught until the end of the 20th century.
Since Simpson's 1945 classification, the paleontological record has been recalibrated, and the intervening years have seen much debate and progress concerning the theoretical underpinnings of systematization itself, partly through the new concept of cladistics. Though field work gradually made Simpson's classification outdated, it remained the closest thing to an official classification of mammals. See list of placental mammals and list of monotremes and marsupials for more detailed information on mammal genera and species.
Molecular studies by molecular systematists, based on DNA analysis, in the early 21st century have revealed new relationships among mammal families. Classification systems based on molecular studies reveal three major groups or lineages of placental mammals- Afrotheria, Xenarthra, and Boreotheria- which diverged from early common ancestors in the Cretaceous.
The relationships between these three lineages is contentious, and all three have been proposed as basal in different hypotheses.
The first divergence was that of the Afrotheria 110–100 million years ago (mya). The Afrotheria proceeded to evolve and diversify in the isolation of the African-Arabian continent. The Xenarthra, isolated in South America, diverged from the Boreoeutheria approximately 100–95 mya. The Boreoeutheria split into the Laurasiatheria and Euarchontoglires between 95 and 85 mya; both of these groups evolved on the northern continent of Laurasia.
After tens of millions of years of relative isolation, Africa-Arabia collided with Eurasia, and the formation of the Isthmus of Panama linked South America and North America, facilitating the distribution of mammals seen today. With the exception of bats and murine rodents, no placental land mammals reached Australasia until the first human settlers arrived approximately 50,000 years ago.
It should however be noted that these molecular results are still controversial mainly because they are not reflected by morphological data and thus not accepted by many systematists. It is also important to note that fossil taxa are not and, in most cases cannot, be included. Although there are instances of DNA being recovered from prehistoric mammals such as the ground sloth Mylodon and Neanderthal humans, Homo neanderthalensis, fossils can generally only be incorporated in morphological analyses.
The following taxonomy only includes living placentals (infraclass Eutheria):
Clade Afroinsectiphilia
Order Macroscelidea
Family Macroscelididae: (17 species), elephant shrews (Africa)
Order Afrosoricida
Family Tenrecidae: (30 species), tenrecs (Madagascar) and otter-shrews (West and Central Africa)
Family Chrysochloridae: (21 species), golden moles (Africa south of the Sahara)
Order Tubulidentata
Family Orycteropodidae: (1 species), aardvark (Africa south of the Sahara)
Clade Paenungulata
Order Proboscidea
Family Elephantidae: (3 species), elephants (Africa, Southeast Asia)
Order Hyracoidea
Family Procaviidae: (4 species), hyraxes, dassies (Africa, Arabia)
Order Sirenia
Family Dugongidae: (1 species), dugong (East Africa, Red Sea, North Australia)
Family Trichechidae: (3 species), manatees (tropical Atlantic coasts and adjacent rivers)
Order Cingulata
Family Chlamyphoridae: (14 species), armadillos (Neotropical)
Family Dasypodidae: (7 species), armadillos (Neotropical and Nearctic)
Order Pilosa
Family Cyclopedidae: (1 species), silky anteater (Neotropical)
Family Myrmecophagidae: (3 species), anteaters (Neotropical)
Family Megalonychidae: (2 species), two-toed sloths (Neotropical)
Family Bradypodidae: (4 species), three-toed sloths (Neotropical)
Superorder Euarchonta
Order Scandentia
Family Ptilocercidae (1 species), pen-tailed treeshrews (Southeast Asia)
Family Tupaiidae: (19 species), treeshrews (Southeast Asia)
Clade Primatomorpha
Order Dermoptera
Family Cynocephalidae: (2 species), flying lemurs or colugos (Southeast Asia)
Order Primates: lemurs, bushbabies, monkeys, apes (cosmopolitan).
Family Cheirogaleidae: (32 species), dwarf lemurs (Madagascar)
Family Lemuridae: (22 species), lemurs (Madagascar)
Family Lepilemuridae: (26 species), sportive lemurs (Madagascar)
Family Indriidae: (19 species), indri and sifakas (Madagascar)
Family Daubentoniidae: (1 species), aye-aye (Madagascar area)
Family Lorisidae: (9 species), lorises and potto (Africa and Southeast Asia)
Family Galagidae: (19 species), galagos (Africa)
Family Tarsiidae: (9 species), tarsiers (Southeast Asia)
Family Callitrichidae: (41 species), marmosets and tamarins (South America)
Family Cebidae: (14 species), New World monkeys (South America)
Family Cercopithecidae: (137 species), Old World monkeys (Africa and Eurasia)
Family Hylobatidae: (14 species), gibbons (Southeast Asia)
Family Hominidae: (7 species), great apes (worldwide)
Superorder Glires
Order Lagomorpha: pikas, rabbits, hares (Eurasia, Africa, Americas)
Family Leporidae: (60 species), rabbits and hares (Eurasia, Africa, Americas)
Family Ochotonidae: (30 species), pikas (Holarctic)
Order Rodentia: rodents (cosmopolitan)
Family Aplodontiidae: mountain beaver (North America)
Family Sciuridae: squirrels, chipmunks, and marmots (cosmopolitan except Australia)
Family Gliridae: dormice (Africa, Eurasia)
Family Castoridae: beavers (Holarctic)
Family Geomyidae: pocket gophers (North America)
Family Heteromyidae: kangaroo rats (North America)
Family Dipodidae: jerboas and jumping mice (Africa, Eurasia, North America)
Family Platacanthomyidae: spiny dormouse (Southeast Asia)
Family Spalacidae: zokors, root rats, blind mole rats (Africa, Eurasia)
Family Calomyscidae: mouse-like hamsters (Asia)
Family Nesomyidae: old endemic African muroids (Africa, Madagascar)
Family Cricetidae: hamsters, voles, and New World rats and mice (Holarctic, South America)
Family Muridae: Old World rats and mice and gerbils (Africa, Eurasia, Australia)
Family Anomaluridae: scaly-tailed flying squirrels (Africa)
Family Pedetidae: springhaas (Africa)
Family Ctenodactylidae: gundis (Africa, Asia)
Family Hystricidae: Old World porcupines (Africa, Asia)
Family Bathyergidae: African mole-rats (Africa)
Family Petromuridae: rock dassies (Africa)
Family Thryonomyidae: cane rats (Africa)
Family Erethizontidae: New World porcupines (New World)
Family Chinchillidae: chinchillas and viscachas (South America)
Family Dinomyidae: pacarana (South America)
Family Caviidae: cavies and capybara (South America)
Family Dasyproctidae: agoutis and acouchis (South America)
Family Cuniculidae: paca (South America)
Family Ctenomyidae: tuco-tucos (South America)
Family Octodontidae: degus (South America)
Family Abrocomidae: chinchilla-rats (South America)
Family Echimyidae: spiny rats (South America)
Family Capromyidae: hutias (South America)
Family Myocastoridae: nutrias (South America)
Order Eulipotyphla
Family Solenodontidae: solenodons (Cuba, Hispaniola)
Family Soricidae: shrews (Eurasia, Africa, North America to northern South America)
Family Talpidae: moles, shrew-moles, desmans (Eurasia, North America)
Family Erinaceidae: hedgehogs, moonrats (Eurasia, Africa)
Clade Ferungulata
Cohort Cetartiodactyla: includes orders Artiodactyla and Cetacea
Family Camelidae: camels (South America, Asia)
Family Suidae: pigs (Africa, Eurasia)
Family Tayassuidae: peccaries (New World)
Family Hippopotamidae: hippos (Africa)
Family Balaenopteridae: rorquals and grey whales
Family Balaenidae: right and bowhead whales
Family Kogiidae: dwarf sperm whales
Family Physeteridae: sperm whales
Family Ziphiidae: beaked whales
Family Platanistidae: river dolphins
Family Delphinidae: dolphins
Family Pontoporiidae: La Plata River dolphin
Family Lipotidae: baiji
Family Iniidae: Amazon River dolphin
Family Monodontidae: beluga and narwhal
Family Phocoenidae: porpoises
Family Tragulidae: mouse-deer (Africa, Asia)
Family Antilocapridae: pronghorn (North America)
Family Giraffidae: giraffe and okapi (Africa)
Family Cervidae: deer (Holarctic, South America)
Family Moschidae: musk deer (Asia)
Family Bovidae: cattle, antelope, sheep, etc. (Africa, Holarctic)
Clade Pegasoferae
Order Chiroptera: bats (cosmopolitan)
Family Pteropodidae: flying foxes (Africa, Eurasia, Australia)
Family Rhinolophidae: Old World horseshoe and leaf-nosed bats (Old World)
Family Emballonuridae: sac-winged bats (southern continents)
Family Craseonycteridae: Kitti's hog-nosed bat (Thailand)
Family Rhinopomatidae: mouse-tailed bats (Africa, Southeast Asia)
Family Nycteridae: slit-faced bats (Africa, Southeast Asia)
Family Megadermatidae: false vampire bats (Africa, Southeast Asia, Australia)
Family Phyllostomidae: leaf-nosed bats (South America)
Family Mormoopidae: leaf-chinned bats (South America)
Family Noctilionidae: fishing bats (South America)
Family Mystacinidae: short-tailed bats (New Zealand)
Family Molossidae: free-tailed bats (cosmopolitan)
Family Myzopodidae: sucker-footed bats (Madagascar)
Family Thyropteridae: sucker-footed bats (South America)
Family Furipteridae: smoky bats (South America)
Family Natalidae: funnel-eared bats (South America)
Family Vespertilionidae: vesper bats (cosmopolitan)
Order Perissodactyla: odd-toed ungulates
Family Equidae: horses, zebras, donkeys (Africa, West and Central Asia)
Family Tapiridae: tapirs (Central and South America, Southeast Asia)
Family Rhinocerotidae: rhinoceroses (Africa, Southeast Asia)
Clade Ferae
Order Pholidota
Family Manidae: pangolins, scaly anteaters (Africa, South Asia)
Order Carnivora: carnivorans (cosmopolitan)
Family Felidae: cats
Family Viverridae: civets, Asiatic palm civets
Family Herpestidae: mongooses
Family Hyaenidae: hyaenas, aardwolf
Family Canidae: dogs
Family Ursidae: bears
Family Otariidae: eared seals
Family Odobenidae: walrus
Family Phocidae: seals
Family Ailuridae: red panda
Family Mephitidae: skunks
Family Mustelidae: weasels and relatives
Family Procyonidae: ringtails, olingos, kinkajou, raccoons, coatis
Standardized textbook classification
A somewhat standardized classification system has been adopted by most current mammalogy classroom textbooks. The following taxonomy of extant and recently extinct mammals is taken from Vaughan et al. (2000). This approach emphasizes an initial split between egg-laying prototherians and live-bearing therians. The therians are further divided into the marsupial Metatheria and the "placental" Eutheria. No attempt is made in this classification to further distinguish among the orders within these subclasses and infraclasses. This system also makes no note of the position of entirely fossil groups.
In this and later taxonomies, families are merely listed under the order to which they belong. More detailed relationships among families is presented in the article of each order.
Order Monotremata
Family Tachyglossidae (echidnas)
Family Ornithorhynchidae (platypuses)
Infraclass Metatheria (marsupials and their nearest ancestors)
Order Didelphimorphia
Family Didelphidae (opossums, etc.)
Order Paucituberculata
Family Caenolestidae (shrew opossums)
Order Microbiotheria
Family Microbiotheriidae (monito del montes)
Order Dasyuromorphia (most carnivorous marsupials)
Family Thylacinidae (Tasmanian tigers)
Family Myrmecobiidae (numbats)
Family Dasyuridae (Tasmanian devils, quolls, dunnarts, planigale, etc.)
Order Peramelemorphia (bandicoots, bilbies, etc.)
Family Peramelidae
Family Peroryctidae
Order Notoryctemorphia (marsupial moles)
Family Notoryctidae
Order Diprotodontia
Family Phascolarctidae (koalas)
Family Vombatidae (wombats)
Family Phalangeridae (brushtail possums and cuscuses)
Family Potoroidae (bettongs, potoroos and rat kangaroos)
Family Macropodidae (kangaroos, wallabies, etc.)
Family Burramyidae (pygmy possums)
Family Pseudocheiridae (ringtailed possums, etc.)
Family Petauridae (striped possum, Leadbeater's possum, yellow-bellied glider, sugar glider, mahogany glider and squirrel glider)
Family Tarsipedidae (honey possum)
Family Acrobatidae (feathertail glider and feather-tailed possum)
Infraclass Eutheria
Order Xenarthra
Family Bradypodidae
Family Megalonychidae
Family Dasypodidae
Family Myrmecophagidae
Order Insectivora
Family Solenodontidae
Family Nesophontidae
Family Tenrecidae
Family Chrysochloridae
Family Erinaceidae
Family Soricidae
Family Talpidae
Order Scandentia
Family Tupaiidae
Order Dermoptera
Family Cynocephalidae
Order Chiroptera
Family Pteropodidae
Family Emballonuridae
Family Craseonycteridae
Family Rhinopomatidae
Family Nycteridae
Family Megadermatidae
Family Rhinolophidae
Family Phyllostomidae
Family Mormoopidae
Family Noctilionidae
Family Mystacinidae
Family Molossidae
Family Myzopodidae
Family Thyropteridae
Family Furipteridae
Family Natalidae
Family Vespertilionidae
Order Primates
Family Daubentoniidae
Family Lemuridae
Family Lepilemuridae
Family Galagidae
Family Lorisidae
Family Cheirogaleidae
Family Indriidae
Family Tarsiidae
Family Cercopithecidae
Family Hominidae
Family Hylobatidae
Family Callitrichidae
Family Cebidae
Order Carnivora
Family Felidae
Family Viverridae
Family Herpestidae
Family Hyaenidae
Family Canidae
Family Ursidae
Family Otariidae
Family Phocidae
Family Odobenidae
Family Mustelidae
Family Procyonidae
Order Cetacea
Family Balaenopteridae
Family Eschrichtiidae
Family Balaenidae
Family Neobalaenidae
Family Physeteridae
Family Ziphiidae
Family Platanistidae
Family Delphinidae
Family Monodontidae
Family Phocoenidae
Order Sirenia
Family Dugongidae
Family Trichechidae
Order Proboscidea
Family Elephantidae
Order Perissodactyla
Family Equidae
Family Tapiridae
Family Rhinocerotidae
Order Hyracoidea
Family Procaviidae
Order Tubulidentata
Family Orycteropodidae
Order Artiodactyla
Family Suidae
Family Tayassuidae
Family Hippopotamidae
Family Camelidae
Family Tragulidae
Family Giraffidae
Family Moschidae
Family Cervidae
Family Antilocapridae
Family Bovidae
Order Pholidota
Family Manidae
Order Rodentia
Family Aplodontiidae
Family Sciuridae
Family Castoridae
Family Geomyidae
Family Heteromyidae
Family Dipodidae
Family Muridae
Family Anomaluridae
Family Pedetidae
Family Ctenodactylidae
Family Myoxidae
Family Bathyergidae
Family Hystricidae
Family Petromuridae
Family Thryonomyidae
Family Erethizontidae
Family Chinchillidae
Family Dinomyidae
Family Caviidae
Family Hydrochaeridae
Family Dasyproctidae
Family Agoutidae
Family Ctenomyidae
Family Octodontidae
Family Abrocomidae
Family Echimyidae
Family Capromyidae
Family Heptaxodontidae
Family Myocastoridae
Order Lagomorpha
Family Ochotonidae
Family Leporidae
Order Macroscelidea
Family Macroscelididae
In 1997, the mammals were comprehensively revised by Malcolm C. McKenna and Susan K. Bell, which has resulted in the "McKenna/Bell classification".
McKenna and Bell, Classification of Mammals: Above the species level, (McKenna & Bell, 1997) is a comprehensive work on the systematics, relationships, and occurrences of all mammal taxa, living and extinct, down through the rank of genus. The authors worked together as paleontologists at the American Museum of Natural History, New York. McKenna inherited the project from Simpson and, with Bell, constructed a completely updated hierarchical system, covering living and extinct taxa that reflects the historical genealogy of Mammalia.
The McKenna/Bell hierarchical listing of all of the terms used for mammal groups above the species includes extinct mammals as well as modern groups, and introduces some fine distinctions such as legions and sublegions and (ranks which fall between classes and orders) that are likely to be glossed over by the layman.
Click on the highlighted link for a table comparing the traditional and the new McKenna/Bell classifications of mammals
Extinct groups are represented by †.
(monotremes)
Order Platypoda: platypuses
Family Ornithorhynchidae: platypuses
Order Tachyglossa: echidnas (spiny anteaters)
Family Tachyglossidae: echidnas
Infraclass †Allotheria
Order †Multituberculata: multituberculates
Family †Plagiaulacidae
Family †Bolodontidae
Family †Hahnodontidae
Family †Albionbaataridae
Family †Arginbaataridae
Family †Kogaionidae
Family †Sloanbaataridae
Family †Cimolodontidae
Family †Ptilodontidae
Family †Cimolomyidae
Family †Eucosmodontidae
Family †Taeniolabididae
Family †Ferugliotheriidae
Family †Sudamericidae
Family †Patagoniidae
Family †Groeberiidae
Infraclass †Triconodonta
Family †Amphilestidae
Family †Triconodontidae
Infraclass Holotheria
Family †Chronoperatidae
Superlegion †Kuehneotheria
Family †Kuehneotheriidae
Family †Woutersiidae
Superlegion Trechnotheria
Legion †Symmetrodonta
Family †Shuotheriidae
Order †Amphidontoidea
Family †Amphidontidae
Order †Spalacotherioidea
Family †Tinodontidae
Family †Spalacotheriidae
Family †Barbereniidae
Legion Cladotheria
Sublegion †Dryolestoidea
Order †Dryolestida
Family †Austrotriconodontidae
Family †Dryolestidae
Family †Paurodontidae
Family †Donodontidae
Family †Mesungulatidae
Family †Reigitheriidae
Family †Brandoniidae
Order †Amphitheriida
Family †Amphitheriidae
Sublegion Zatheria
Family †Arguitheriidae
Family †Arguimuridae
Family †Vincelestidae
Infralegion †Peramura
Family †Peramuridae
Infralegion Tribosphenida
Family †Necrolestidae
Supercohort †Aegialodontia
Family †Aegialodontidae
Supercohort Theria: therian mammals
Family †Pappotheriidae
Family †Holoclemensiidae
Family †Kermackiidae
Family †Endotheriidae
Family †Picopsidae
Family †Potamotelsidae
Family †Plicatodontidae
Order †Deltatheroida
Family †Deltatheridiidae
Family †Deltatheroididae
Order †Asiadelphia
Family †Asiatheriidae
Family †Stagodontidae
Family †Pediomyidae
Cohort Marsupialia: marsupials
Family †Yingabalanaridae
Magnorder Australidelphia
Superorder Microbiotheria
Family Microbiotheriidae: monito del monte
Superorder Eometatheria
Order †Yalkaparidontia
Family †Yalkaparidontidae
Order Notoryctemorphia: marsupial moles
Family Notoryctidae: marsupial moles
Grandorder Dasyuromorphia: marsupial carnivores
Family †Thylacinidae: recently extinct Tasmanian tiger and relatives
Family Dasyuridae: Tasmanian devil, quolls, etc.
Family Myrmecobiidae: numbat
Grandorder Syndactyli: syndactylous marsupials
Order Peramelia: bandicoots
Family Peramelidae
Family Peroryctidae
Order Diprotodontia
Family †Palorchestidae
Family †Wynardiidae
Family †Thylacoleonidae
Family Tarsipedidae: honey possum
Family †Ilariidae
Family †Diprotodontidae
Family Vombatidae: wombats
Family Phalangeridae: phalangers
Family Burramyidae: pygmy possums
Family Macropodidae: rat kangaroos, kangaroos and wallabies
Family Petauridae: gliders
Family †Ektopodontidae
Family Phascolarctidae: koala
Family †Pilkipildridae
Family †Miralinidae
Family Acrobatidae: feather-tail glider, pen-tailed phalanger
Magnorder Ameridelphia
Order Didelphimorphia: opossums
Family Didelphidae: opossums
Family †Sparassocynidae
Order Paucituberculata
Family †Sternbergiidae
Family Caenolestidae: rat or shrew opossums
Family †Paleothentidae
Family †Abderitidae
Family †Sillustaniidae
Family †Polydolopidae
Family †Prepidolopidae
Family †Bonapartheriidae
Family †Argyrolagidae
Family †Glasbiidae
Family †Caroloameghiniidae
Order †Sparassodonta
Family †Mayulestidae
Family †Hondadelphidae
Family †Borhyaenidae
Cohort Placentalia: placentals
Order †Bibymalagasia
Magnorder Xenarthra: edentates
Order Cingulata: armadillos and relatives
Family Dasypodidae: armadillos
Family †Peltephilidae
Family †Pampatheriidae
Family †Palaeopeltidae
Family †Glyptodontidae: glyptodonts
Order Pilosa: anteaters, sloths, and relatives
Family †Entelopidae
Family Myrmecophagidae: giant anteaters and relatives
Family Cyclopedidae: pygmy anteater
Family †Rathymotheriidae
Family †Scelidotheriidae
Family †Mylodontidae
Family †Megatheriidae: ground sloths
Family Megalonychidae: two-toed sloths
Family Bradypodidae: three-toed sloths
Magnorder Epitheria: epitheres
Superorder †Leptictida
Family †Gypsonictopidae
Family †Kulbeckiidae
Family †Didymoconidae
Family †Leptictidae
Superorder Preptotheria
Grandorder Anagalida
Family †Zambdalestidae
Family †Anagalidae
Family †Pseudictopidae
Mirorder Macroscelidea: elephant shrews
Family Macroscelididae: elephant shrews
Mirorder Duplicidentata
Order †Mimotonida
Family †Mimotonidae
Order Lagomorpha
Family Ochotonidae: pikas
Family Leporidae: rabbits
Mirorder Simplicidentata
Order †Mixodontia
Family †Eurymylidae
Order Rodentia: rodents
Family †Alagomyidae
Family †Laredomyidae
Family †Ischyromyidae
Family †Allomyidae
Family Aplodontiidae: mountain beaver
Family †Mylagaulidae
Family †Theridomyidae
Family †Reithroparamyidae
Family Sciuridae: squirrels
Family †Eutypomyidae
Family Castoridae: beavers
Family †Rhizospalacidae
Family †Protoptychidae
Family †Armintomyidae
Family Dipodidae: jumping mice, jerboas
Family †Simimyidae
Family Muridae: rats, mice, and relatives
Family Myoxidae: dormice
Family †Eomyidae
Family †Florentiamyidae
Family Geomyidae: pocket gophers, pocket mice, and kangaroo rats
Family Pedetidae: springhaas
Family †Parapedetidae
Family †Zegdoumyidae
Family Anomaluridae: scaly-tailed squirrels
Family †Ivanantoniidae
Family †Sciuravidae
Family †Chapattimyidae
Family †Cylindrodontidae
Family Ctenodactylidae: gundis
Family †Tsaganomyidae
Family Hystricidae: Old World porcupines
Family Erethizontidae: New World porcupines
Family †Myophiomyidae
Family †Diamantomyidae
Family †Phiomyidae
Family †Kenyamyidae
Family Petromuridae: rock rats
Family Thryonomyidae: cane rats
Family Bathyergidae: mole-rats
Family †Bathyergoididae
Family Agoutidae: agoutis and pacas
Family †Eocardiidae
Family Dinomyidae: pacarana
Family Caviidae: cavies
Family Hydrochoeridae: capybara
Family Octodontidae: degus, tuco-tucos
Family Echimyidae: spiny rats, nutria
Family Capromyidae: hutias
Family †Heptaxodontidae
Family Chinchillidae: chinchillas, viscachas
Family †Neoepiblemidae
Family Abrocomidae: rat chinchillas
Grandorder Ferae
Order Cimolesta - pangolins and relatives
Family †Palaeoryctidae
Family †Cimolestidae
Family †Apatemyidae
Family †Stylinodontidae
Family †Tillotheriidae
Family †Wangliidae
Family †Harpyodidae
Family †Bemalambdidae
Family †Pastoralodontidae
Family †Titanoideidae
Family †Pantolambdidae
Family †Barylambdidae
Family †Cyriacotheriidae
Family †Pantolambdodontidae
Family †Coryphodontidae
Family †Pantolestidae
Family †Paroxyclaenidae
Family †Ptolemaiidae
Family †Epoicotheriidae
Family †Metacheiromyidae
Family Manidae: pangolins
Family †Ernanodontidae
Order †Creodonta: creodonts
Family †Hyaenodontidae
Family †Oxyaenidae
Order Carnivora
Family †Viverravidae
Family †Nimravidae
Family Felidae: cats
Family Viverridae: civets, Asiatic palm civets
Family Herpestidae: mongooses
Family Hyaenidae: hyaenas, aardwolf
Family Nandiniidae: African palm civets
Family †Miacidae
Family Canidae: dogs
Family †Amphicyonidae
Family Ursidae: bears
Family †Hemicyonidae
Family Otariidae: eared seals
Family Phocidae: seals, walrus
Family Mustelidae: weasels, skunks, and relatives
Family Procyonidae: ringtails, olingos, kinkajou, raccoons, coatis, red panda
Grandorder Lipotyphla
Family †Adapisoriculidae
Order Chrysochloridea
Family Chrysochloridae: golden moles
Order Erinaceomorpha
Family †Sespedectidae
Family †Amphilemuridae
Family †Adapisoricidae
Family †Creotarsidae
Family Erinaceidae: hedgehogs and relatives
Family †Proscalopidae
Family Talpidae: moles
Family †Dimylidae
Order Soricomorpha
Family †Otlestidae
Family †Geolabididae
Family †Nesophontidae: recently extinct west Indian shrews
Family †Micropternodontidae
Family †Apternodontidae
Family Solenodontidae: solenodons
Family †Plesiosoricidae
Family †Nyctitheriidae
Family Soricidae: shrews
Family Tenrecidae: tenrecs
Grandorder Archonta
Order Chiroptera: bats
Family Pteropodidae: flying foxes
Family †Archaeonycteridae
Family †Paleochiropterygidae
Family †Hassianycterididae
Family Emballonuridae: sac-winged bats
Family Rhinopomatidae: mouse-tailed bats
Family Craseonycteridae: bumblebee bats
Family Megadermatidae: false vampire bats
Family Nycteridae: hispid bats
Family Rhinolophidae: horseshoe and Old World leaf-nosed bats
Family Mystacinidae: New Zealand short-tailed bats
Family Noctilionidae: fishing bats
Family Mormoopidae: spectacled bats
Family Phyllostomidae: New World leaf-nosed and vampire bats
Family †Philisidae
Family Molossidae: free-tailed bats
Family Natalidae: funnel-eared bats
Family Furipteridae: smoky bats
Family Thyropteridae: New World sucker-footed bats
Family Myzopodidae: Old World sucker-footed bats
Family Vespertilionidae: common bats
Order Primates: primates
Family †Purgatoriidae
Family †Microsyopidae
Family †Micromomyidae
Family †Picromomyidae
Family †Plesiadapidae
Family †Palaechthonidae
Family †Picrodontidae
Family †Paramomyidae
Family †Plagiomenidae
Family †Mixodectidae
Family Galeopithecidae: colugos
Family †Plesiopithecidae
Family Daubentoniidae: aye-aye
Family †Adapidae
Family Lemuridae: lemurs
Family Lorisidae: lorises and galagos
Family Cheirogaleidae: dwarf lemurs
Family †Archaeolemuridae
Family †Palaeopropithecidae
Family Indriidae: indris and sifakas
Family †Carpolestidae
Family †Omomyidae
Family †Microchoeridae
Family †Afrotarsiidae
Family Tarsiidae: tarsiers
Family †Eosimiidae
Family †Parapithecidae
Family †Pliopithecidae
Family Cercopithecidae: Old World monkeys including colobuses
Family Hominidae: humans, greater apes, lesser apes
Family Callitrichidae: marmosets
Family Atelidae: New World monkeys
Order Scandentia
Family Tupaiidae: tree shrews
Grandorder Ungulata: ungulates
Order Tubulidentata
Family Orycteropodidae: aardvark
Order †Dinocerata
Family †Uintatheriidae
Mirorder Eparctocyona
Order †Procreodi
Family †Oxyclaenidae
Family †Arctocyonidae
Order †Condylarthra
Family †Hyopsodontidae
Family †Mioclaenidae
Family †Phenacodontidae
Family †Periptychidae
Family †Peligrotheriidae
Family †Didolodontidae
Order †Arctostylopida
Family †Arctostylopidae
Order Cete: whales and relatives
Family †Triisodontidae
Family †Mesonychidae: mesonychids
Family †Hapalodectidae
Family †Basilosauridae
Family †Protocetidae
Family †Remingtonocetidae
Family †Agorophiidae
Family †Squalodontidae
Family †Rhabdosteidae
Family †Aetiocetidae
Family †Mammalodontidae
Family †Cetotheriidae
Family Balaenopteridae: rorquals and grey whales
Family Balaenidae: right and bowhead whales
Family Physeteridae: sperm whales
Family Hyperoodontidae: beaked whales
Family Platanistidae: river dolphins
Family Delphinidae: dolphins
Family Pontoporiidae: La Plata River dolphin
Family Lipotidae: baiiji
Family Iniidae: Amazon River dolphin
Family †Kentridontidae
Family Monodontidae: beluga and narwhal
Family †Odobenocetopsidae
Family †Dalpiazinidae
Family †Acrodelphinidae
Family Phocoenidae: porpoises
Family †Albireonidae
Family †Hemisyntrachelidae
Order Artiodactyla: even-toed ungulates
Family †Raoellidae
Family †Choeropotamidae
Family Suidae: pigs
Family Tayassuidae: peccaries
Family †Santheriidae
Family Hippopotamidae: hippos
Family †Dichobunidae
Family †Cebochoeridae
Family †Mixtotheriidae
Family †Helohyidae
Family †Haplobunodontidae
Family †Anthracotheriidae
Family †Dacrytheriidae
Family †Anoplotheriidae
Family †Cainotheriidae
Family †Agriochoeridae
Family †Oreodontidae
Family †Entelodontidae
Family †Xiphodontidae
Family Camelidae: camels and llamas
Family †Oromerycidae
Family †Protoceratidae
Family †Amphimerycidae
Family †Hypertragulidae
Family Tragulidae: mouse deer
Family †Leptomerycidae
Family †Bachitheriidae
Family †Lophiomerycidae
Family †Gelocidae
Family Moschidae: musk deer
Family Antilocapridae: pronghorn
Family †Palaeomerycidae
Family †Hoplitomerycidae
Family Cervidae: deer
Family †Climacoceratidae
Family Giraffidae: giraffe and okapi
Family Bovidae: cattle, antelope, and relatives
Mirorder †Meridiungulata
Family †Perutheriidae
Family †Amilnedwardsiidae
Order †Litopterna
Family †Protolipternidae
Family †Macraucheniidae
Family †Notonychopidae
Family †Adianthidae
Family †Proterotheriidae
Order †Notoungulata: notoungulates
Family †Henricosborniidae
Family †Notostylopidae
Family †Isotemnidae
Family †Leontiniidae
Family †Notohippidae
Family †Toxodontidae
Family †Homalodotheriidae
Family †Archaeopithecidae
Family †Oldfieldthomasiidae
Family †Interatheriidae
Family †Campanorcidae
Family †Mesotheriidae
Family †Archaeohyracidae
Family †Hegetotheriidae
Order †Astrapotheria
Family †Eoastrapostylopidae
Family †Trigonostylopidae
Family †Astrapotheriidae
Order †Xenungulata
Family †Carodniidae
Order †Pyrotheria
Family †Pyrotheriidae
Mirorder Altungulata
Order Perissodactyla: odd-toed ungulates
Family Equidae: horses
Family †Palaeotheriidae
Family †Brontotheriidae
Family †Anchilophidae
Family †Eomoropidae
Family †Chalicotheriidae
Family †Hyracodontidae
Family Rhinocerotidae: rhinoceroses
Family †Helaletidae
Family †Isectolophidae
Family †Lophiodontidae
Family †Deperetellidae
Family †Lophialetidae
Family Tapiridae: tapirs
Order Uranotheria: elephants, manatees, hyraxes, and relatives
Family †Pliohyracidae
Family Procaviidae: hyraxes
Family †Phenacolophidae
Family †Arsinoitheriidae
Family †Prorastomidae
Family Dugongidae: dugongs
Family Trichechidae: manatees
Family †Desmostylidae
Family †Anthracobunidae
Family †Moeritheriidae
Family †Numidotheriidae
Family †Barytheriidae
Family †Deinotheriidae
Family †Palaeomastodontidae
Family †Phiomiidae
Family †Hemimastodontidae
Family †Mammutidae: mastodons and relatives
Family †Gomphotheriidae: gomphotheres
Family Elephantidae: modern elephants
Luo, Kielan-Jaworowska, and Cifelli classification
Several important fossil mammal discoveries have been made that have led researchers to question many of the relationships proposed by McKenna and Bell (1997). Additionally, researchers are subjecting taxonomic hypotheses to more rigorous cladistic analyses of early mammal fossils. Luo et al. (2002) summarized existing ideas and proposed new ideas of relationships among mammals at the most basal level. They argued that the term mammal should be defined based on characters (especially the dentary-squamosal jaw articulation) instead of a crown-based definition (the group that contains most recent common ancestor of monotremes and therians and all of its descendants). Their definition of Mammalia is roughly equal to the Mammaliaformes as defined by McKenna and Bell (1997) and other authors. They also define their taxonomic levels as clades and do not apply Linnean hierarchies.
Mammalia
†Sinoconodon - earliest and most basal of mammals
Unnamed clade 1 - a clade that contains all other mammals. These are characterized by determinant growth and occlusal features of the cheek teeth.
†Morganucodontidae - morganucodontids, including †Morganucodon, †Megazostrodon, and others
†Docodonta - docodonts, including †Haldanodon and †Castorocauda (Ji et al., 2006)
Unnamed clade 2 - a clade containing all living mammals and some fossil relatives. It is characterized by the loss of a postdentary trough and a widened braincase.
†Hadrocodium
†Kuehneotherium
Crown-group Mammalia - the group that contains most recent common ancestor of monotremes and therians and all of its descendants. This group is defined by additional characters relating the occlusion of molars and the presence of a well-developed masseteric fossa.
Australosphenida - a clade that contains monotremes and their fossil relatives. These fossils include †Ambondro, †Asfaltomylos, †Ausktribosphenos, and †Bishops. If correct, this clade represents an independent evolution of the tribosphenic molar in southern continents.
Trechnotheria - Therians, spalacotheriids and their relatives. They are characterized by features of the scapula, tibia, and humerus.
†Spalacotheriidae - including Akidolestes, Zhangheotherium, and Maotherium.
Cladotheria - Therians, dryolestids, and their relatives. They are characterized by features of the tribosphenic molar and the angular process of the dentary.
†Dryolestidae
†Amphitherium - incertae sedis (it may be a prototribosphenidan)
Prototribosphenida - Therians and fossil relatives including †Vincelestes. Characterized by features of the cochlea including coiling.
†Vincelestes
Zatheria - Therians and fossil relatives including the "peramurids". Characterized by the presence of wear in the talonid of the lower molars.
†"Peramuridae" - †Peramus and relatives. Known only from preserved mandibles and distinctly zatherian molars.
Boreosphenida - Therians and fossil relatives including †Kielantherium. They are characterized by molar features.
†Kielantherium
†Deltatheroida including †Deltatheridium - incertae sedis (it may represent a metatherian)
Crown-group Theria - the group that contains most recent common ancestor of marsupials and placentals and all of its descendants. Characterized by a host of molar features, aspects of the alispenoid, and aspects of the astragalus region.
†Eutriconodonta - incertae sedis. Triconodonts appear to be a member of the crown-Mammalia clade, but their relationships within it are unknown. It is also not certain that they represent a monophyletic group. Examples include Repenomamus.
†Multituberculata - incertae sedis. Luo e al. (2002) argue that multituberculates cannot be confidently placed in a particular clade of mammals. They suggest that they represent either basal mammals or are sister to the Trechnotheria.
The following classification is a simplified version based on current understanding suitable for non-specialists who want to understand how living genera are related to each other. The classification ignores differences in levels and thus cannot be used to estimate the respective distances between taxa. It also ignores taxa that became extinct in pre-historic times. Finally, English names are preferred whenever they exist. This makes it especially suited for non-specialists who wish to gain an easy overview. For the full picture, the non-simplified versions above should be consulted.
Monotremes (prototheria): echidnas and platypus
Platypus
Echidnas (tachyglossids)
Live-bearing mammals (theria)
Marsupials
Opossums (didelphids)
Shrew opossums (caenolestids)
Australodelphia: Australian marsupials and monito del Monte
Monito del Monte
Dasyuromorphs
Dasyurids: antechinuses, quolls, dunnarts, Tasmanian devil, and allies
Numbat
Peramelemorphs: bilbies and bandicoots
Bilbies (thylacomyids)
Bandicoots (peramelids)
Marsupial moles (notoryctids)
Diprotodonts
Koala
Wombats (vombatids)
Phalangerids: brushtail possums and cuscuses
Pygmy possums (burramyids)
Honey possum
Petaurids: striped and Leadbeater's possums, and yellow-bellied, suger, mahogany and squirrel glider
Ringtailed possums (pseudocheirids)
Potorids: potoroos, rat kangaroos and bettongs
Acrobatids: feathertail glider and feather-tailed possum
Musky rat-kangaroo
Macropodids: kangaroos, wallabies and allies
Placentals
Atlantic placentals (atlantogenatans)
Afroplacentals (afrotherians)
Afroinsectiphilians: elephant shrews, tenrecs, otter shrews, golden moles, and aardvark
Elephant shrews (macroscelidids)
Afrosoricids: tenrecs and golden moles
Tenrecids: tenrecs and otter shrews
Golden moles (chrysochlorids)
Aardvark
Paenungulates: hyraxes, elephants, dugongs and manatees
Hyraxes or dassies (procaviids)
Elephants (elephantids)
Sirenians: dugong and manatees
Dugong
Manatees (trichechids)
Xenarthrans
Pilosans: sloths and anteaters
Anteaters (vermilinguans)
Silky anteater
Myrmecophagids: giant anteater and tamanduas
Sloths (folivorans)
Three-toed sloths (bradypodids)
Two-toed sloths (megalonychids)
Armadillos (dasypodids)
Northern placentals (boreoeutherians)
Supraprimates (euarchontoglires)
Euarchontans: treeshrews, colugos and primates
Treeshrews (scandentians)
Tupaiids: all treeshrews except pen-tailed
Pen-tailed treeshrew
Colugos or flying lemurs (cynocephalids)
Primates
Strepsirrhines: lemur- and loris-like primates
Lemur-like primates (lemuriforms)
Cheirogaleids: dwarf lemurs and mouse-lemurs
Aye-aye
True lemurs (lemurids)
Sportive lemurs (lepilemurids)
Indriids: woolly lemurs and allies
Loris-like primates (lorisiforms)
Lorisids: lorises, pottos and allies
Galagos (galagids)
Haplorhines: tarsiers, monkeys and apes
Tarsiers (tarsiids)
Anthropoid primates
New World monkeys (platyrrhines)
Callitrichids: marmosets and tamarins
Cebids: capuchins and squirrel monkeys
Aotids: night or owl monkeys
Pitheciids: titis, sakis and uakaris
Atelids: howler, spider, woolly spider, and woolly monkeys
Catarrhines
Old World monkeys (cercopithecids)
Hominoid primates
Gibbons (hylobatids)
Great apes (hominids): incl. Humans
Glires: pikas, rabbits, hares, and rodents
Lagomorphs: pikas, rabits and hares
Leporids: rabbits and hares
Pikas (ochotonids)
Rodents
Anomalure-like rodents (anomaluromorphs): Scaly-tailed squirrels and springhares
Scaly-tailed squirrels or anomalures (anomalurids)
Springhares (pedetids)
Beaver-like rodents (castorimorphs)
Beavers (castorids)
Gopher-like rodents (geomyoid rodents)
Pocket or true gophers (geomyids)
Heteromyids: kangaroo rats and kangaroo mice
Porcupine-like rodents (hystricomorphs)
Laotian rock rat
Gundis (ctenodactylids)
Hystricognaths
African mole rats (bathyergids)
Old World porcupines (hystricids)
Dassie rat
Cane rats (thryonomyids)
Cavy-like rodents (caviomorphs)
Chinchilla rats (abrocomids)
Hutias (capromyids)
Cavies (caviids): incl. Guinea pigs and capybara
Chinchillids: chinchillas and viscachas
Tuco-tucos (ctenomyids)
Agoutis (dasyproctids)
Pacas (cuniculids)
Pacarana
Spiny rats (echymyids)
New World porcupines (erethizontids)
Myocastorids: nutria and coypu
Octodonts (octodontids): Andean rock-rats, degus and viscacha-rats
Mouse-like rodents (myomorphs)
Dipodids: jerboas and jumping mice
Muroid rodents
Mouse-like hamsters (calomyscids)
Cricetids: hamsters, New World rats and mice, voles
Murids: true mice and rats, gerbils, spiny mice, crested rat
Nesomyids: climbing mice, rock mice, white-tailed rat, Malagasy rats and mice
Spiny doormice (platacanthomyids)
Spalacids: mole rats, bamboo rats, and zokors
Squirrel-like rodents (sciuromorphs)
Mountain beaver
Doormice (glirids)
Squirrels (sciurids): incl. chipmunks, prairie dogs, and marmots
Laurasian placentals (laurasiatherians)
Hedgehogs (erinaceids)
Soricomorphs: moles, shrews, solenodons
Shrews (soricids)
Moles (talpids)
Solenodons (solenodontids)
Ferungulates: ungulates, cetaceans, bats, pangolins and carnivorans
Cetartiodactyls: camels, swine, cetaceans, hippos, and ruminants
Camelids: camels and llamas
Swine (suinans): pigs and peccaries
Pigs (suids)
Peccaries (tayassuids)
Cetruminantians: cetaceans hippos and ruminants
Cetancodonts: Cetaceans and hippos
Cetaceans: Whales, dolphins and porpoises
Baleen whales (mysticetes)
Balaenids: right whales and bowhead whale
Rorquals (balaenopterids)
Gray whale
Pygmy right whale
Toothed whales (odontocetes)
Dolphins (delphinids)
Monodontids: beluga and narwhal
Beluga
Narwhal
Porpoises (phocoenids)
Sperm whale
Kogiids: pygmy and dwarf sperm whale
River dolphins (platanistoid whales)
Iniids: Amazon and Bolivian river dolphin
La Plata dolphin
Platanistids: Ganges and Indus river dolphins
Beaked whales (ziphids)
Hippos (hippopotamids)
Ruminantiamorphs: chevrotains, pronghorn, giraffes, musk deer, deer, and bovids
Chevrotains (tragulids)
Pecorans
Pronghorn
Giraffids: giraffe and okapi
Musk deer (moschids)
Deer (cervids)
Bovids: cattle, goats, sheep and antelope
Pegasoferans: bats, odd-toed ungulates, pangolins and carnivorans
Bats (chiropterans)
Megabats (pteropodids)
Microbats (microchiropterans)
Sac-winged or sheath-tailed bats (emballonurids)
Rhinopomatoid bats
Mouse-tailed bats (rhinopomatids)
Bumblebee bat or Kitti's hog-nosed bat
Rhinolophoid bats
Horseshoe bats (rhinolophids)
Hollow-faced or slit-faced bats (nycterids)
False vampires (megadermatids)
Vesper bats or evening bats (vespertilionids)
Molossoid bats
Free-tailed bats (molossids)
Pallid bats (antrozoids)
Nataloid bats
Funnel-eared bats (natalids)
Sucker-footed bats (myzopodids)
Disc-winged bats (thyropterids)
Smoky bats (furipterids)
Noctilionoid bats
Bulldog or fisherman bats (noctilionids)
New Zealand short-tailed bats (mystacinids)
Ghost-faced or moustached bats (mormoopids)
Leaf-nosed bats (phyllostomids)
Zooamatans: odd-toed ungulates, pangolins and carnivorans
Odd-toed ungulates (perissodactyls)
Horses (equids)
Ceratomorphs
Tapirs (tapirids)
Rhinoceroses (rhinocerotids)
Ferans
Pangolins or scaly anteaters (manids)
Carnivorans
Cat-like carnivorans (feliforms)
African palm civet
Feloid carnivorans
Asiatic linsangs (prionodontids)
Cats (felids)
Viverroid carnivorans
Viverrids: civets and allies
Herpestoid carnivorans
Hyaenids: hyenas and aardwolf
Malagasy carnivorans (euplerids)
Herpestids: mongooses and allies
Dog-like carnivorans (caniforms)
Canids: dogs and allies
Arctoid carnivorans
Bears (ursids)
Musteloid carnivorans
Red panda
Mephitids: skunks and stink badgers
Mustelids: weasels, martens, badgers, wolverines, minks, ferrets and otters
Procyonids: raccoons and allies
Pinnipeds
Walrus
Otariids: sea lions, eared seals, fur seals
True seals (phocids)
